KENYA STANDARD                                                               KS 2110-3:2009 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
CCTV  surveillance systems for use in security  applications —  
 
Part 3: System design requirements  
   
 
 
 
 
 
 
 
 
 
 
 
           
 
             PUBLIC REVIEW DRAFT,MARCH 2009 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
 
 
                               TECHNICAL COMMITTEE REPRESENTATION 
 
The following organizations were represented on the  Technical Committee:  
 
Eveready Batteries Kenya Ltd. 
Associated Battery Manufacturers 
Kenya Railways Corporation 
Securicor Alarms (K) Ltd. 
Department of Defence 
Ministry of Roads and Public Works  
Kenya Power & Lighting Company Ltd.  
Automotive Industrial Battery Manufacturers (A.I.B. M) (K) Ltd . 
Ministry of Energy 
Jomo Kenyatta University of Agriculture and Technol ogy — Electrical Engineering Department. 
Kenya Bureau of Standards — Secretariat 
 
 
 
 
 
REVISION OF KENYA STANDARDS 
 
In order to keep abreast of progress in industry, K enya Standards shall be regularly reviewed. Suggest ions 
for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards , 
are welcome. 
 
                                     © Kenya Bureau of Standards, 2009 
 
Copyright:  Users are reminded that by virtue of se ction 6 of the Copyright Act, Cap. 130 of the Laws of Kenya, copyright subsists in all 
Kenya Standards and except as provided under sectio n 7 of this Act, no Kenya Standard produced by Keny a Bureau of Standards may 
be reproduced, stored in a retrieval system in any form or transmitted by any means without prior perm ission in writing from the 
Managing Director 
ISBN 
 
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 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
 
 
 
Foreword 
 
This Kenya Standard was developed by the Technical Committee on Extra-low Voltage and is in accordance  
with the procedures of the Bureau. 
 
In the preparation of this Kenya Standard reference  was made to SANS 10222-5-1-2:2007   
 
Acknowledgement is hereby made for assistance deriv ed from this source. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
CCTV surveillance systems for use in security appli cations –  
Part 3: System design requirements 
 
1 Scope  
This part of Kenya standard gives recommendations f or the general design requirements for CCTV 
surveillance systems used in security applications.  
 
The objectives of this part of Kenya Standard are t o 
a) Provide an overview of typical CCTV equipment fe atures and functions, 
b) Assist in specifications and enable users in det ermining the appropriate equipment required for a g iven 
application 
c) Provide guidance in the preparation of typical C CTV system design specifications. 
 
2 Normative references  
 
The following standards contain provisions which, t hrough reference in this text, constitute provision s of this 
part of Kenya Standard.  All standards are subject to revision and, since any reference to a standard is 
deemed to be a reference to the latest edition of t hat standard, parties to agreements based on this p art of 
Kenya Standard are encouraged to take steps to ensu re the use of the most recent editions of the stand ards 
indicated below. Information on currently valid nat ional and international standards can be obtained f rom the 
Kenya Bureau of Standards. 
 
KS 2110-1-  Installation and remote monitoring of detector act ivated CCTV systems- code of practice 
 
KS 2110-2  – CCTV surveillance  systems for use in security applications – Operatio nal requirements . 
 
KS 2110-4 – CCTV surveillance  systems for use in security applications – Installa tion requirements . 
 
KS 2110-5 – CCTV surveillance  systems for use in security applications – Testing,  commissioning and handover 
requirements . 
 
KS 2110-6 – CCTV surveillance  systems for use in security applications – Maintena nce requirements . 
 
 
3 Definitions and abbreviations  
 
For the purposes of this Kenya Standard, the follow ing definitions and abbreviations apply: 
 
3.1 Definitions  
 
        3.1.1  
        Aperture number of the lens  (f)  
The index of the theoretical light-gathering power of the lens, expressed as the ratio of the effectiv e diameter        
of the lens (entrance pupil) to the focal length of  the lens 
 
3.1.2  
Back focus  
The distance between the external surface of the le ns that is closest to the imaging device and the fo cal 
point of the lens 
 
3.1.3  
C & CS mount  
Mounting format of various camera lenses 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  3.1.4  
Camera housing  
An enclosure to provide physical or environmental p rotection (or both) of the camera, lens and ancilla ry 
equipment 
 
3.1.5  
Camera sensitivity  
Imaging device illumination necessary to produce a defined composite (colour) video signal amplitude w ith a 
defined signal-to-noise ratio 
 
3.1.6  
CCTV camera  
A unit that contains an imaging device that produce s a video signal from an optical image 
 
3.1.7  
CCTV camera equipment  
A unit that contains a CCTV camera plus appropriate  lenses and the necessary ancillary equipment 
 
3.1.8  
CCTV control unit  
Equipment for controlling and monitoring the requir ed operational functions of the CCTV system 
 
3.1.9  
CCTV surveillance installation  
An installation consisting of the hardware and soft ware components of a CCTV system, fully installed a nd 
operational for monitoring a defined security zone 
 
3.1.10 
CCTV surveillance system  
A system that consists of camera equipment, monitor ing and associated equipment for transmission and 
controlling purposes, which may be necessary for th e surveillance of a defined security zone 
 
3.1.11  
Character generator  
A device for generating alphanumeric characters or symbols (or both) and adding them into the image 
 
3.1.12  
Composite colour video signal  
CCVS 
The video output signal of a colour camera, which s ignal comprises the burst and colour information 
(colour), the picture component (video), black refe rence (blanking) and the synchronization components  
(synchronization) 
 
3.1.13  
Composite video signal  
CVS 
The video output signal of a black and white (b/w) CCTV camera comprising the picture component (video ), 
black reference (blanking) and the synchronization components (synchronization) 
 
3.1.14  
Decibel 
A measure of the voltage or power ratio of two sign als; decibel gain or loss is 20 times log 10 of the  voltage 
or current ratio, and 10 times log 10 of the power ratio 
 
3.1.15  
Electronic iris   
An automatic electronic shutter that varies the CCT V camera sensitivity in relation to the varying lig ht   
conditions in order to maintain the video output si gnal within defined limits 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  3.1.16  
Electronic shutter  
An arrangement in a CCTV camera for changing its se nsitivity by electronically controlling its exposur e time 
 
3.1.17  
Event recording  
The event controlled recording or storing of image signals for a predetermined time 
 
3.1.18  
External synchronization  
A method of feeding reference timing signals to all  connected devices to ensure that their video outpu t 
signals are synchronous 
 
3.1.19  
Focal length  (F)  
A property of a lens, expressed in millimeters, giv ing the angle of view for a given sensor size 
 
 
3.1.20  
Imaging device  
A device that converts an optical image into an ele ctrical signal 
 
3.1.21  
Imaging device illumination  
The level of illumination (illuminance) at the phot osensitive surface of the imaging device 
 
3.1.22  
Image sensor size  
The size of the light sensitive surface of the imag ing device 
 
NOTE: The value is expressed in inches and refers t o the diameter of the glass tube from which the cam era tubes are constructed or, 
in the case of CCD cameras, the diagonal measuremen t of the sensor. 
 
Some examples of sizes are: 
 
–   1 inch for 12.8 × 9.6 mm (16 mm diagonal) 
 
– 2/3inch for 8.8 × 6.6 mm (11 mm diagonal) 
 
–   ½ inch for 6.4 × 4.8 mm (8 mm diagonal) 
 
– 1/3 inch for 4.8 × 3.6 mm (6 mm diagonal) 
 
3.1.23  
Iris  
A variable-aperture mechanism that regulates the am ount of light that passes through the lens onto the  
imaging device of the CCTV camera 
 
 
3.1.24  
Lens  
An optical device for projecting an image of a desi red scene onto the photosensitive surface of the im aging 
device 
 
3.1.25  
Pan-and-tilt camera unit  
A motorized unit permitting the vertical and horizo ntal positioning of the camera equipment 
 
3.1.26  
Picture storage  
The storing of video images 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  3.1.27  
Preset shot  
A function in pan-and-tilt camera units or zoom len ses (or both) that allows automatic return to one o r more 
predetermined positions 
 
3.1.28  
Scene illumination  
The level of illumination (illuminance) on the area  to be kept under surveillance 
3.1.29  
Scene reflectance  
The proportion of the scene illumination reflected by that scene 
 
3.1.30  
Slow-scan transmission  
The transmission of a series of non-real-time image s or part images by means of analogue or digital si gnals 
over limited-bandwidth transmission media 
 
3.1.31  
Time and date generator  
A device for generating the time and date and incor porating them into the image 
 
3.1.32  
Time-lapse recording  
the periodical recording of video signals at predef ined intervals 
 
3.1.33  
Time multiplex recording  
A method for recording several video signals on one  video channel by time-multiplexing the frames of t hese 
video signals 
 
3.1.34  
Transmission number of lens ( T) 
The index of the actual light-gathering power of th e lens 
 
3.1.35  
Variable focal length lens  
A lens with variable focal length in which the imag e does not remain in focus as the focal length chan ges 
 
3.1.36  
Video equalizing amplifier  
Equipment for correcting gain-related and frequency -related distortions in the video signal 
 
3.1.37  
Video matrix  
A unit for connecting several input video signals t o several outputs 
 
3.1.38  
Video monitor  
A device for converting video signals into pictures  on a display screen 
 
3.1.39  
Video printer  
Equipment for converting a video signal into an ima ge on paper 
 
3.1.40  
Video switcher  
A unit for switching a number of video input signal s to one or more outputs manually or automatically or on 
receipt of an external signal 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  3.1.41  
Zoom lens  
A lens with adjustable focal length, in which the i mage of the scene remains in focus as the focal len gth is 
changed 
 
3.2 Abbreviations  
 
3.2.1 CCD:  Charge-coupled device 
 
3.2.2 CCIR:  Comité Consultatif International des Radio communi cation (International Radio Consultative 
Committee) 
 
3.2.3 CCTV:  closed-circuit television 
 
3.2.4 dB:  decibel 
 
3.2.5 RF:  radio frequency 
 
3.2.6 SPD:  surge protection device 
 
3.2.7 UPS:  uninterruptible power supply 
 
3.2.8 VCR:  video cassette recorder 
 
3.2.9 VHS:  video home system 
 
 
 
4 The role of CCTV in security applications  
 
In its broadest sense, the purpose of CCTV in a sec urity application is for a security operator to cre ate live-
action displays from a distance. The CCTV system sho uld also include a recording capability,  either a VCR or other 
storage media, to maintain a permanent record of th e displayed events for evidence purposes. The typic al 
hardware components of a CCTV system will include f our basic components, namely (a) camera(s), lens(es), 
monitor(s) and transmission link(s). In addition to  these  basic components, comprehensive CCTV systems would  
include one or more video switchers, multiplexers, matrix switchers, recorders, hard-cop y printers and ancillary 
equipment. See annex A for  the layout schematic of a typical large CCTV syste m. 
 
Some applications for which CCTV provides an effect ive solution are 
 
a) Overt visual observation of a scene or activity from a remote location, 
b) Covert observation of a scene, 
 
c) Recording of a scene when triggered by an alarm sensor, 
d) Observation of many locations simultaneously fro m a central control point, and 
e) Providing video evidence when a crime has been c ommitted. 
 
5 System design criteria  
 
 
When designing a CCTV surveillance system installat ion, the following criteria should be taken into ac count, 
bearing in mind the need to meet the operational re quirement: 
 
a) Determination of the zones or objects that requi re surveillance; 
b) Determination of the number of cameras, and thei r locations, required to monitor the agreed zones o r 
objects; 
c) Evaluation of existing lighting and consideratio n of new or additional illumination; 
d) Selection of cameras and equipment, depending on  the environmental operating conditions; 
e) control-point configuration; KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  f) Power supplies; 
g) Determination of functional and operating proced ures; and 
h) Maintenance. 
 
The determination of the zones or objects to be cov ered by the CCTV system will be provided by the oper ational 
requirement document (see SABS 0222-5-1-1 or the equiv alent Kenya Standard). All other aspects of the abov e-
mentioned criteria should be considered by the designer of th e complete CCTV system.  
 
6. Equipment overview  
  
NOTE: This clause provides an overview of the indiv idual items of equipment that comprise a CCTV syste m with regard 
to fundamentals of operation and the terms used to specify operational performance. 
6.1 Cameras  
 
6.1.1 Specifications  
 
At present there is no standard method for manufact urers to present data that define camera performanc e. 
Therefore, it is essential that manufacturers' spec ification literature be studied very carefully and that 
comparisons be made against a common standard befor e making a selection. 
 
6.1.2 Fundamentals of operation  
 
The function of the camera is to convert the visibl e scene formed by the lens into an electrical signa l suitable 
for transmission to the monitor, recorder or printe r. The camera consists of 
 
a) An image sensor, 
b) Some form of electrical scanning system with syn chronization, 
c) Timing electronics, 
d) Video amplifying and process electronics, and 
e) Video signal synchronizing and combining electro nics to produce a composite video output signal. 
 
6.1.3 Types of camera  
 
6.1.3.1 General  
 
Two basic types of cameras exist, namely cameras wi th tube-type sensors and cameras with solid-state 
sensors. Although tube-type cameras can still be fo und in some of the older types of CCTV security 
installations, solid-state cameras have now become the standard. 
6.1.3.2 Tube cameras  
 
The tube camera video signal is extracted from the hollow glass tube by means of an electron beam, whi ch 
scans the entire scene in 1/25th of a second. This electron beam is emitted by an electron gun, which 
produces electrons and accelerates them towards the  sensor target photocathode, which generates a sign al 
proportional to the light intensity on the sensor. Apart from the tube sensor, the remaining camera 
electronics are solid-state. Tube cameras can provi de excellent resolution because the target is a 
homogeneous continuous surface. However, tube camer as are no longer readily available and therefore th is 
part of SABS 0222 will only concern itself with sol id-state cameras.  
 
6.1.3.3 Solid-state cameras  
 
A solid-state sensor performs similarly to the tube  camera but has a significantly different sensor an d 
scanning system. Instead of an electron beam scanni ng the tube, an array of pixels is used. These 
effectively replace the sensor tube and produce ele ctrical signals in response to the light level of t he scene. 
 
Solid-state sensors are available in several types,  such as CCD, CPD, CID and MOS. Of these types, the  
CCD (or charge coupled device) is by far the most p opular. Typical sensor format sizes are ¼ inch,an i nch, 
and ½ inch. Some of the advantages of CCD cameras a re as follows: 
 
a) There is no geometric distortion. 
b) There are no coils, magnets or glass tube. KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  c) They are not prone to ghosting or image burn. 
d) They are more compact and resistant to vibration . 
e) They are not affected by electromagnetic interfe rence. 
6.1.3.4 Low-light-level cameras  
 
Low-light-level cameras are used to view scenes ill uminated by natural moonlight, starlight or some ot her 
very-low-light-level artificial illumination. These  cameras use image intensifiers connected to imagin g tubes 
or solid-state sensors and are capable of viewing s cenes far from the camera under low- light-level 
conditions. Low-light-level cameras are not infrare d (IR) sensitive, are only available in monochrome,  cost 
between ten and twenty times more than a standard c amera, and are normally used only in special 
applications. 
6.1.4 Performance specification  
 
6.1.4.1 Resolution  
 
CCTV resolution is the ability of a camera to resol ve detail: the higher the resolution the sharper th e image. 
Resolution is measured by the number of horizontal and vertical TV lines that can be discerned in the 
monitor picture. Vertical resolution is determined by the CCTV format used and is therefore seldom inc luded 
in camera data sheets. The system used in South Afr ica is the European PAL format of 625 lines, with a  
maximum achievable resolution of 408 lines. Horizon tal resolution is the resolution quoted in camera d ata 
sheets. Unlike vertical resolution, which is limite d by the 625 line system, horizontal resolution can  be 
improved by using more pixels in the matrix. Typica lly, the resolution of monochrome cameras range fro m 
270 to 600 TV lines and that of colour cameras from  330 to 500 TV lines. Generally, the higher the 
resolution the more expensive the camera, and so co rrect camera selection for the view required is 
important to keep costs down. For example, a genera l view of an area would use a low resolution, but w here 
the identification of people is essential a higher resolution camera would be used. 
 
 
6.1.4.2 Signal-to-noise ratio  
 
The effect of noise in a video picture depends on t he ratio of the noise level to the video signal lev el. This 
ratio is expressed in decibels (dB). A ratio of 1 0 00:1, where the video signal is 1 000 times greater  than the 
noise level, is equivalent to a level of 60 dB. In a video signal, values from 45 dB to60 dB produce a n 
acceptable picture. Less than 45 dB is unlikely to produce an acceptable picture. At 20 dB the picture  will be 
unusable. The signal-to-noise ratio of a camera has  an effect on its sensitivity. This is because the better the 
ratio at a given light level, the lower the minimum  light level before the picture becomes unusable. 
 
6.1.4.3 Sensitivity  
 
The sensitivity of a camera is basically the minimu m level of light needed to view a picture. The lowe r the 
light level, the fewer electrons or charges are pro duced by the image sensor owing to light falling on  it. 
Sensitivity is usually expressed in lux, which is t he density of light measured in lumens per square m eter. 
 
There are two main methods of describing the sensit ivity of a camera. The most precise, but not very 
practical, method is to define the face-plate value . The other more common and practical method is for  the 
scene sensitivity to be stated in lux at a given f-number and scene reflectance. For example, a CCD c amera 
can have a scene sensitivity of 0,4 lux usable vide o for a scene reflectance of 75 %(see clause 7) vie wed 
with an f 1.4 lens. Obviously a camera will appear more sens itive if the face-plate value is given because no 
light is lost from the scene or through the lens. T hat is why care must be taken when looking at camer a data 
sheets to find out exactly what the true sensitivit y is. As a guide, face-plate sensitivity is normall y 10 times 
that for scene sensitivity at an aperture of f 1.4. The best judgement is, ultimately, how the ca mera actually 
performs in the field. 
 
6.1.4.4 Spectral response  
 
Cameras have a range of light to which they respond  better than to other ranges and the spectral respo nse 
of a camera is the sensitivity of the imaging devic e to the different frequencies of light. Since diff erent 
camera types respond to different  colours, it is i mportant to know what type of light source is illum inating the KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  subject area, as well as what type might have to be  added to obtain the required picture quality. More  
information on this topic can be found in clause 7.  
 
6.1.5 Camera synchronization  
 
All cameras have their own internal synchronization  generators to enable the monitor to recreate the p icture. 
However, when more than one camera is being used, s witching between camera views on a monitor will 
produce "picture roll", which at the least can be v ery irritating, especially if several monitors are in use that 
all show sequences of cameras. 
 
One method of overcoming this problem is to use an external stable generator to create synchronization  
pulses. However, a better (and more popular) method  is to use line-lock or variable phase locking in w hich 
the synchronization pulses are referenced to the AC  power supply frequency. Obviously DC cameras canno t 
use this method and the external generator would be  required. 
 
6.1.6 Camera adjustments and controls  
 
6.1.6.1 Automatic gain control  
 
Automatic gain control (AGC) is the process whereby  the gain of the video signal is automatically incr eased 
if it falls below the "full video" level owing to l ow light levels. The amplification or gain of a cam era is given in 
decibels – typically 20 dB, which is equivalent to amplifying the signal 10 times. 
Most cameras have a switch to enable the AGC to be switched on and off. AGC control is not normally 
required for internal scenes where the light levels  are reasonable and constant. 
 
6.1.6.2 Automatic light control  
 
Automatic light control (or ALC) is normally associ ated with the use of automatic iris lenses. A separ ate 
output on the rear of the camera has a control sign al that opens and closes the iris of the lens depen ding on 
the amount of light entering the lens, so that the light level onto the image device is always correct . 
 
6.1.6.3 Electronic shutter  
 
The electronic shutter basically switches the charg ed coupled device (CCD) on and off many times a 
second. Very rapid switching of the CCD has the eff ect of reducing the sensitivity of the camera. This  can be 
compared with setting a fast shutter speed on a nor mal photographic camera. The result is that very ra pid 
movements are captured more sharply on the CCD and when the VCR tape is played back there will be no 
blurring of moving objects. Using a low shutter spe ed, on the other hand, will mean that there are les s than 
25 frames per second and so the camera will not pro duce moving images. However, it will give more time  for 
light to fall on the CCD and hence increase the sen sitivity of the camera to above the normal sensitiv ity at 25 
frames per second. In this way a colour camera can be made to produce usable colour pictures at light 
levels well below one lux. 
 
6.1.6.4 White balance  
 
A white-balance control is found only on colour cam eras as the quality of the colour picture produced by the 
camera will change depending on the light level and  the spectrum of the light on the scene. This contr ol has 
basically two positions, namely automatic and manua l. In the automatic position the camera adjusts its elf in 
terms of the black and white levels of the blue and  red signals. In the manual position a potentiomete r can 
be adjusted to vary the picture from blue to red to  obtain the right balance. Some cameras have a simp le 
change-over switch to either set the balance for ou tdoor scenes or to set the balance for indoor scene s that 
are lit by artificial light. 
 
6.1.6.5 Back-light compensation  
 
A camera with no back-light compensation or with th e back-light compensation turned off responds to th e 
average content of the entire video signal. With ba ck-light compensation turned on, the camera establi shes 
a central area for automatic light control. If an o bject falls within this area, the camera will autom atically 
adjust to set the optimum contrast, thus ensuring a  usable picture of the object. This is particularly  useful 
when the camera is directed towards areas of bright  light such as doorways, windows and backlit scenes . KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  However, back-light compensation is not a panacea f or problems of this type and its benefits should be  
treated with circumspection. 
 
6.2 Lenses  
6.2.1 General  
 
The function of the CCTV lens is to collect the ref lected light from a scene and focus it onto the cam era 
sensor. Choosing the proper lens is very important,  since the lens determines the amount of light rece ived 
by the camera sensor, as well as the field of view and the quality of the image. There are aids availa ble, 
such as tables, slide rules and the circular lens-f inder kit that helps the designer to select the bes t lens for a 
particular CCTV application in respect to the field  of view required. In addition a focal length finde r, 
calibrated with the different camera formats, can b e used to obtain a visual indication of the expecte d 
camera view. 
 
6.2.2 Lens mount formats  
 
All cameras have a mount in front of the sensor to mechanically couple the lens to the camera. Earlier  tube-
type cameras used a standard configuration known as  the C mount, whereas new cameras mainly use a 
new range of lenses that uses a CS mount configurat ion. The difference between the two types is the fl ange 
back length, which is the distance from the back fl ange of the lens to the face of the sensor. The scr ew 
thread and shoulder length of each type of mount ar e identical, which makes it impossible to see the 
difference, although the overall size of the CS mou nt is generally smaller. A C mount can be used on a  CS 
mount camera with an adapter ring, but a CS mount c annot be used on a C mount camera. If the wrong typ e 
is used it will be impossible to focus the camera. In addition, some C mounts have a projection at the  back 
that could damage the sensor of the CS mount camera  if the C mount is screwed directly into the camera  
without the adapter ring. A lens designed for a lar ger format camera (say 1 inch) can be used on small er 
format cameras (say b inch, ½ inch), but the revers e is not possible. However, the field of view will be 
reduced. 
 
 
6.2.3 Focal length and field of view  
 
6.2.3.1 General  
 
A lens has two focal points, namely the primary foc al point and the secondary focal point. The focal l ength of 
a lens is the distance from the lens centre to the primary focal point and is expressed in millimetres . The 
field of view of a lens is the actual area of a pic ture that can be seen, and is determined by the len s focal 
length, the sensor size and the distance to the obj ect being viewed. Many lens suppliers provide simpl e 
calculators that use the relationship between these  factors to determine the corresponding field of vi ew, the 
most common type of calculator being the disk type.  In simple terms, the larger the focal length the n arrower 
the angle of view. Table 1 shows the relationship b etween lens size and sensor format in terms of fiel d of 
view. Lenses are available in different focal-lengt h formats, such as fixed focal length, variable foc al length, 
and zoom. 
 
6.2.3.2 Fixed-focal-length lenses  
 
A fixed-focal-length lens has a field of view that is fixed and it normally comes with a manual iris, to adjust 
the amount of light that passes through the lens, a nd a manual focusing ring. However, short- focal-le ngth 
(wide angle of view) lenses often lack a focusing r ing or a manual iris. These types of lenses are nor mally 
available in focal lengths from 2.8 mm to 75 mm. Th e angle of view for each focal length can be obtain ed 
from the manufacturer's data sheets. 
 
6.2.3.3 Variable-focal-length lenses  
 
A variable-focal-length lens has a limited range of  manual focal-length adjustments and is useful in i nternal 
situations where precise adjustment of the scene is  necessary, especially where the adjustment falls 
between two standard fixed-focal-length lenses. Var iable-focal-length lenses are also useful because, at a 
small extra cost, one lens type can be specified fo r all cameras in the system, which gives a saving o n 
installation time and the cost of possible return v isits to change lenses if the view is not quite rig ht. 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
Table 1- Relationship between different lens format s 
 
         1            2            3           4               5            6 
                   Equivalent focal lengths (mm)              Angles of View 
                   Degrees                                    Sensor size 
1 inch 2/3 inch ½ inch 1/3 inch Horizontal Vertical  
360 
280 
210 
180 
150 
140 
105 
100 
75 
50 
30 
25 
20 
16 
12.5 
10 
- 
- 
- 249 
194 
145 
124 
103 
97 
73 
69 
52 
35 
21 
17.3 
13.9 
11.1 
8.5 
6.9 
6.2 
5.9 
5.5 181 
141 
105 
90 
75 
70 
53 
50 
38 
25 
15 
12.6 
10.1 
8.1 
6.3 
5.0 
4.5 
4.3 
4.0 136 
105 
79 
68 
56 
52 
39 
38 
28 
19 
11 
9.0 
7.6 
6.0 
4.7 
3.8 
3.4 
3.2 
3.0 2.0 
2.4 
3.7 
4.1 
4.5 
5.4 
6.9 
7.1 
9.3 
14.3 
23.8 
28.5 
35.1 
43.2 
53.6 
65.0 
70.7 
73.4 
77.3 1.5 
2.0 
2.6 
3.0 
3.6 
3.9 
5.2 
5.5 
7.3 
10.9 
18.0 
21.6 
26.7 
33.1 
41.5 
51.1 
56.0 
58.4 
61.9 
 
 
 
 
 
 
 
 
 
6.2.3.4 Manual zoom lens  
 
A manual zoom lens is one in which the focal length  can be varied manually by means of a ring on the l ens 
body. The zoom ratio is normally stated as being, f or instance 6:1, which means that the longest focal  length 
is six times that of the shortest. The usual way of  describing a zoom lens is by format size zoom rati o, and 
shortest and longest focal lengths, for example 2/3  inch, 6:1, 12.5 mm to 75 mm. Care should be taken in 
establishing both the camera and lens format. The l ens described in the example would only have a rang e 
of 8 mm to 48 mm on a ½ inch camera. 
 
6.2.3.5 Motorized zoom lens 
 
Motorized zoom lenses are not widely used with fixe d cameras as the angle of tilt of the camera often has to 
be changed as the lens is zoomed in and out. The mo st common need for a motorized zoom lens is when it  
is used with a pan-and-tilt camera unit. In this in stance the lens zoom ring is driven by a tiny DC mo tor and 
operated from a remote controller. With the use of smaller cameras the lens is often much larger than the 
camera it is attached to and therefore it might be necessary to mount the lens with a rigid support an d have 
the camera supported by the lens. 
6.2.4 Lens iris  
 
6.2.4.1 General  
 
 
A lens iris is an adjustable optomechanical device for controlling the amount of light that passes thr ough the KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  lens and impinges on the sensor device. A lens may have a fixed iris, manually controlled iris or 
automatically controlled iris. 
 
6.2.4.2 Manual iris  
 
A manual iris has movable metal "leaves" that form the iris. The iris can be manually opened or closed  by 
using an adjusting ring to adjust the amount of lig ht passing through the lens. A lens that uses this type of 
iris is only suitable for internal applications whe re the light levels remain fairly constant. This ty pe of iris can 
also be used with cameras having an electronic shut ter feature. In some situations, where the levels o f light 
entering through windows etc. may vary between summ er and winter, it might be necessary to adjust the iris 
during the course of the year to maintain optimum c larity of the picture. 
 
6.2.4.3 Automatic iris  
 
To overcome the light-level problems experienced wi th manual-iris lenses, automatic irises use motors to 
automatically drive the iris adjusting ring to comp ensate for varying light levels. For example, if a scene is 
too bright the motor will close down the iris, thus  reducing the amount of light that can pass through  it, until 
the optimum voltage level of one volt peak-to-peak is reached. Conversely, if the light levels are low  the iris 
will be opened wider to let in extra light. Therefo re, in both high-light-level and low-light-level co nditions the 
automatic iris mechanism adjusts to provide the bes t contrast picture. 
 
There are three main types of automatic iris lenses : 
 
a) Iris amplifier lens:  this is the most common type and has the amplifier  built into the lens body. This 
amplifier is connected to the video signal of the c amera and is driven by a DC voltage (also obtained from 
the camera), either via a plug-type connection or s crew-type connection at the rear of the camera. 
 
b) Galvanometric lens:  the motor of this type of automatic iris lens is d riven by a reference voltage 
produced by an amplifier located in the camera itse lf. These types of lenses are less expensive and ar e 
simple to install but can only be used on a limited  range of cameras. Therefore, it is essential that the 
camera specification be checked to ensure that it c ontains the correct circuitry to drive this type of  lens. 
 
c) Sensor lens:  this lens uses a light sensor to measure the light  levels and adjust the iris accordingly. 
This lens is rarely used and it is unlikely that CC TV system designers will have to include this lens in their 
design. 
 
6.2.5 Aperture and  f-number  
 
The aperture is simply the light gathering area of the lens, and hence it controls the amount of light  that 
reaches the image sensor. The size of the aperture is mechanically controlled; the more light that pas ses 
through the lens and reaches the image sensor, the better the contrast and picture image quality. This  light-
gathering ability or optical speed is related to th e focal length and diameter of the lens and is repr esented by 
what is known as the f-number. The f-numbers, or f-stops, are always indicated by the following numbe rs: f 
0,8; f 1,4; f 2; f 2,8; f 4; f 5,6; f 8; f 11; f 16; f 22 and C. The C indicates that the iris is closed and no light is 
transmitted. The lower the f-number, the more the light that is transmitted by the lens. 
 
6.2.6 Depth of field  
 
Depth of field is a term that relates to what porti on of a picture is in focus and what portion is not , at any 
given light level or iris opening at specific dista nces. Factors that affect the depth of field are th e focal length 
of the lens, the f-number, and the distance to the subject. The wider  the angle of the lens, the more depth of 
field the picture will have; the narrower the angle  (that is, a long focal length), the less the depth  of field will 
be. The higher the f-number, the greater the depth of field will be, th e lower the f-number, the smaller the 
depth of field will be. The depth of field will dec rease when 
 
a) The focal length is longer, 
b) The f-number is larger, and 
c) The subject distance is shorter. 
 
 
6.3 Monitors  KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
6.3.1 General  
 
Ultimately the picture taken by the camera and the lens, possibly via other video equipment, will be 
displayed on a monitor. The monitor's performance a nd adjustment will have an effect on the picture se en 
by the operator. Video images presented on the moni tor have to have a sufficiently high resolution and  
quality to enable the operator to assess the situat ion being displayed. Because the monitor is an anal ogue 
device, it has settings and control adjustments tha t enable the best picture to be displayed. It there fore is 
essential to understand the principles of the norma l monitor controls, their effect on picture quality  and the 
correct way to set the controls. 
 
Monitors are available in screen sizes from approxi mately 5 inches to 20 inches (this is the diagonal 
distance measured across the monitor's screen) (Not e the continuing use of inches to determine monitor  
size.) The choice of the best size of monitor depen ds on the viewing distance. If the incorrect size o r position 
of a monitor is used, the monitor will at best be a wkward and unpleasant to use; and at worst the pict ure will 
be too small to differentiate detail or so large th at the picture appears grainy and of low quality. S ee table 2 
for typical monitor minimum and maximum viewing dis tances. 
 
Table 2 — Monitor viewing distances  
 
 
6.3.2 Performance specifications  
 
6.3.2.1 Resolution  
 
As with cameras, the vertical resolution of a monit or is limited to 625 lines. The figure for resoluti on that is 
normally given in monitor data sheets is, as for ca meras, horizontal resolution. The major difference 
between camera resolution figures and monitor resol ution figures is that the resolution of monitors is  given 
for the centre of the picture. For example, a monit or with a quoted resolution of 600 lines will have 600 lines 
at the centre of the screen and possibly only 400 l ines at the corners. The object to be viewed should  be 
located in the centre of the screen to get the shar pest picture. The horizontal resolution of monochro me (i.e. 
black-and-white) monitors is normally quite high (b etween 750 lines and 800 lines), whereas, because o f the 
three colour spots (red, green and blue) that are n eeded to make each point, the resolution of a colou r 
monitor is lower, i.e. typically between 300 lines and 450 lines. 
 
6.3.2.2 Input impedance and level  
 
The monitor should accept the standard video signal  level of 1 V peak-to-peak and also have an input 
impedance of 75 Ω to match the impedance of the camera and the coaxi al cable. Ideally, this impedance 
should be switchable between 75 Ω and high impedance to allow the video signal to be  looped into another 
monitor. 
 
6.3.2.3 Control settings  
 
Monitors have a number of controls that can be adju sted, namely, an on/off switch and controls for 
brightness, contrast, colour (if it is a colour mon itor), vertical hold and horizontal hold, and a ter mination 
switch. The recommended procedure to set these cont rols is given in another the part of this Kenya 
standard. 
 
 
6.3.3 Selecting and positioning a monitor                                    Monitor 
                                    size                  Recommended viewing distance 
                                       cm 
                             5 inch 
                             9 inch 
                           12 inch 
                           15 inch 
                           20 inch 
 
              30 to 60 
             50 to 105 
             60 to 150 
            70 to 180 
            90 to 240 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
Monitors are normally selected on the basis of thei r specified performance data. However, the size, vi ewing 
distance and positioning of the monitor are just as  important as any technical specification. If the m onitor is 
too small or too far distant, it will not be able t o resolve the detail and for the viewer the whole p urpose of the 
system will be destroyed. Similarly, if the monitor  is too large or too close, the image quality will seem worse 
than it really is. If the monitor is incorrectly pl aced or is at the wrong angle it will be uncomforta ble for the 
operator to use. If there are too many monitors the  operator will simply not be able to take in the ac tivity on 
all screens. The topic of allocating the right numb er of correctly sized monitors in the best position s is 
covered in the next part of this Kenya standard. 
 
6.4 Video switchers  
 
6.4.1 General  
 
The function of the video switcher in any multiple- camera CCTV system is to connect a specific camera to a 
specific monitor (or recorder or other device) and display the video image in a logical sequence. The 
switched pictures on the monitor can be recorded on  a VCR or printed on a video printer. The switcher 
performs a vital function by simplifying system use  and maximizing the information presented to the 
operator. The three basic types of video switchers are: 
 
(a) manual, 
(b) Sequential, and 
(c) Matrix (or microcomputer controlled). 
 
6.4.2 Manual switcher  
 
The manual switcher is the simplest. The operator m anually chooses one camera from a number of cameras  
(by activating front-panel push buttons) for displa y on a single video monitor. This type of switcher 
terminates each camera input with 75 Ω to match the monitor. These switchers are normally  available to 
switch from two to eight camera inputs. 
 
6.4.3 Sequential switcher  
 
The basic homing sequential switcher allows for con tinuous viewing of any sequenced cameras. The 
camera signal is connected to a single video monito r. A three-position switch (designated automatic, h oming 
and bypass) for each camera allows for automatic se lection and switching from one camera to the next, 
according to the sequence set by the operator. The length of time for which each camera picture is 
displayed (known as the dwell time) can be changed by the operator. With the switch set in the home 
position the selected camera is continuously displa yed on the monitor and the sequence stops. The bypa ss 
position removes the camera from the display. As wi th the manual switcher, all camera inputs are corre ctly 
terminated with 75 Ω. These switchers are available to switch from 4 to  16 cameras. Variations on this type 
of switcher include the following: 
 
 a)  Bridging sequential switcher:  operates like a homing switcher but has two monito r outputs to allow 
continuous sequential monitoring at the same time a s individual selected viewing; 
 
 b)  looping-homing sequential switcher:  operates like a homing switcher but allows for all  camera inputs 
to be brought out to a second switcher or other dev ice at another location; 
 
 c) alarming sequential switcher:  automatically displays a picture on the monitor or  starts a VCR each time 
it is activated by an alarm input; available in hom ing, bridging, and looping-homing configurations; a nd 
 
d) Remote sequential switcher:  this switcher consists of two parts, namely a swit ching unit that can be 
situated in a suitable position close to the camera s and a control unit that can be located near the 
monitor(s). These two units are connected by a two- core or four-core cable, or sometimes a single coax ial 
cable. The monitor(s) are connected to the remote u nit via coaxial cable(s). 
 
6.4.4 Matrix switcher  
 
Matrix switchers are now available to cope with the  increasing size and complexity of CCTV systems. 
These types of switchers are based on microprocesso r principles that allow for greater flexibility in routing 
and processing video signals so that any combinatio n of cameras can be connected to any monitor. In 
addition, features such as automatic alarm-activate d video, pan/tilt/zoom control, time/date generatio n and KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  text for camera identification are also provided. M atrix-switched systems can range from simple self-
contained units that control 16 to 32 cameras and s everal monitors and keyboards to a very large syste m 
that controls 1 028 cameras and 99 monitors. Owing to the wide variety of matrix systems available, it  is 
recommended that a final specification be obtained from the various suppliers or manufacturers. Wherev er 
possible, a schematic diagram of the proposed equip ment and control point layout should be provided 
together with a site layout drawing that shows cabl e routes and distances. See annex B for the layout of a 
typical CCTV system that uses a matrix video switch ing system. 
 
6.5 Video multiplexers  
 
6.5.1 General  
 
 
One of the problems associated with video sequence switchers is that only the camera that is being 
displayed will be recorded, assuming that VCR recor ding is being used. For example, assume that the dw ell 
time is set at 4 s for an eight-camera system and t he sequence starts at camera 1. Camera 1 would be 
recorded for 4 s, then camera 2 for 4 s and then ca mera 3 for 4 s, etc. Camera 1 would only be recorde d 
again after 28 s, that is, after the seven remainin g cameras had been recorded for 4 s each. So, for 2 8 s no 
images from camera 1 will be recorded and hence val uable information might be missed. To minimize this  
loss of information, camera video signals can be mu ltiplexed to provide a faster switching/recording r ate with 
the added functionality of multiple camera display.  Pictures from a number of cameras are digitized, 
temporarily held in a frame store and then converte d back to analogue signals and fed in sequence to a  
video tape recorder. That is, a frame from camera 1  is recorded followed by a frame from camera 2, fol lowed 
by a frame from camera 3, and so on until the last camera. The sequence is then repeated for all camer as. 
By using this method, an update time of0.32 s per c amera can be achieved for an eight-camera system. 
This calculation can be explained as follows: 
 
Since 25 frames of video are produced every second in the CCIR standard, the picture is updated every 
0.04 s (or 1/25 s in real time). Therefore, for an eight-camera system, the picture from each camera w ill be 
updated every 0.32 s (that is, 0.04 s x 8 cameras),  and for 16 cameras the update time will be calcula ted by 
multiplying 0.04 s by 16 cameras to get 0.64 s. 
 
If these pictures are being recorded on a VCR in th e 3 h mode (or real-time mode), the recording of ea ch 
camera would also be at 0.32 s (for 8 cameras) or 0 ,64 s (for 16 cameras). However, should the recordi ngs 
be taking place in a time-lapse mode, the update ti me would be increased according to the following 
formula: 
 
t =1/ 25n*m/3 
Where 
 
 
t is the update time expressed in seconds; 
 
n is the number of cameras; 
 
m is the time-lapse mode that has been set. 
 
Example: For a 16-camera system recording in the 24  h time-lapse mode (see 6.6.2), the update time 
would be: 
(1/25 × 16) × (24/3) = 5.12 s 
 
NOTE: These are theoretical times as time-base corr ection could increase them slightly. 
 
It is recommended, in high-security sensitive insta llations, that the 3 h recording mode be used in or der to 
reduce the update time to a minimum. 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  6.5.2 Simplex multiplexers  
 
The basic multiplexer provides only one multiplexed  output, which can either be directed to the monito r 
screen or to a video recorder, but not to both at t he same time. This ability to perform one of the ma in 
multiplexing tasks at any one time, i.e. recording,  playback, or live viewing, is known as simplex ope ration. 
 
6.5.3 Duplex multiplexers  
 
The ability to perform two of the main multiplexer tasks at any one time is known as duplex operation,  such 
as reviewing a video tape while continuing to recor d all cameras. Obviously two VCRs will be required,  one 
for recording and one for same-time playback. The d uplex multiplexer is basically two simplex units 
packaged as one unit. 
 
6.6 Video recorders  
 
6.6.1 General  
 
A video cassette tape recorder (VCR) is a complex i ntegration of electronics and high-precision mechan ics 
and uses a tape contained in a cassette with a supp ly spool and a take-up spool. The tape contains 
thousands of tiny magnets, each with a north and a south pole, and is passed through a varying magneti c 
field. This field is generated in a revolving drum from the video signal and reproduces the video imag e on 
the tape. The standard tape format used is VHS (Vid eo Home System), which was developed by the JVC 
Company of Japan, and the standard tape cassette us ed in security CCTV applications is the E180, which  
records for 180 min at normal speed. The maximum re solution of a video recorder depends on the availab le 
bandwidth. Typically, the resolution of a monochrom e picture is 330 lines and that of a colour picture  is 240 
lines. This has the effect that even if high- resol ution cameras and monitors are used in the CCTV sys tem, 
the recording quality will be limited by the maximu m resolution available from the video recording equ ipment. 
Super VHS recording techniques (that separate the l uminance and chrominance signals and create a wider  
bandwidth) can provide greater resolution than stan dard VHS (typically 500 lines for colour and 400 li nes for 
monochrome). However, the equipment is more expensi ve and the cost of the installation increases since  
additional coaxial cables are required. In addition , there is a limited range of equipment that can sw itch and 
multiplex the separate signals required. 
 
6.6.2 Time-lapse recorders  
 
A time-lapse recorder has the ability to record at different speeds, thus extending the overall record ing 
periods. The recording periods can range from 3 h t o 960 h. The 3 h, 6 h and 12 h mode records 
continuously at a slow speed. For recording periods  longer than 12 h, the recording takes place in a s tep 
mode. In this mode the tape is stepped forward one frame at a time at a rate according to the time sel ected. 
For example, a recording at the 72 h mode would pla yback at the rate of approximately one frame per 
second. Real time is considered to be 25 frames per  second. It should be noted that a person moving at  
eight kilometres per hour will travel over 2 m in 1  s. The greater the time-lapse mode, the more chanc e of 
losing critical information. 
 
6.6.3 Typical features associated with time-lapse r ecorders  
The following is a list of some typical features fo und in most time-lapse recorders: 
 a) Selectable recording mode:  depending on the model, from 3 h to 960 h recordin g is possible; 
b) Horizontal resolution:  the ability to switch between colour and monochrom e to provide higher resolution 
in monochrome; 
 c)  Still frame:  the ability to display a single frame for analysis ; 
d) Alarm recording:  an alarm input will switch the recorder from a tim e-lapse mode (or standby mode) to 3 
h real-time recording for a defined time; 
 e) Alarm search:  the ability to fast-forward until an alarm input i s detected; 
 f) Time and date:  this information can be superimposed on selectable  parts of the screen; 
g) Repeat record:  at the end of the tape it can either stop or rewin d itself and re-record; 
h) Time and date search:  the ability to fast-forward the tape to the requir ed part based on the time and 
date; 
i) End-of-tape alarm:  either a local or remote alarm (or both) to alert a person that the tape end has been 
reached; 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   j) Programmable recording:  to start or stop recording and set recording modes  at specific times; 
k) Battery backup: in the event of a power failure all main settings, such as time and date, programme 
recording, etc will be retained; 
 l) Clock output:  output from an internal synchronization clock to a  video switcher; 
m) Series recording:  at the end of the tape an output signal will start  another recorder to provide 
continuous recording; 
n) One-shot recording:  this allows the recorder to be set to record one f rame at preset intervals; 
o) Emergency recording:  an external trigger signal will switch a recorder to the recording mode even if the 
power is off or the recorder is set in the stop pos ition 
        p) RS-232 output:  to enable the recorder to be interfaced to other e quipment. 
 
6.6.4 Video image/frame storage disk  
 
The real-time or time-lapse video recorder provides  the means for serially recording consecutive frame s 
over a period of time. Even with time and date sear ch the time taken to locate a particular scene or i ncident 
is usually fairly lengthy, since it requires shuttl ing a scene backwards and forwards in order to find  the 
required frame. Other storage mediums are available , but are not readily used because they are expensi ve. 
However, with ever-reducing costs these alternative  devices will eventually replace the analogue video  
recorders that are so commonly used in security CCT V systems. 
 
Some of these devices are given below: 
 
a) analogue magnetic-disk image storage:  analogue pictures are recorded on parallel, circul ar tracks on 
the magnetic disk and accessed in parallel rather t han in series, as required in video tape recording;  this 
greatly reduces the retrieval times; 
 
b) digital magnetic-disk image storage:  the video images are digitized before storage on t he magnetic 
disk 
 
 
c)  Optical-disk image storage:  two generic systems are available, viz. the non-er asable WORM (write-
once read-many) recording system and the erasable o ptical disk, optical disks store significantly larg er 
amounts of video data per disk than the magnetic di sk. 
 
6.7  Hard-copy printers  
 
The hard-copy printout of video monitor scenes, VCR  recordings or other recording media has become an 
important addition to many security systems. Monoch rome and colour printers permit good to excellent 
quality reproduction of the scene on paper or film- based media. This hard copy is used by security 
personnel for apprehending an offender, responding to a security violation, for staff dismissal, for u se as 
evidence in a court of law, or for permanent record  purposes. Several types of printers are available,  the 
most popular being the thermal and film type. These  and the other types are described below: 
 
a) Thermal – monochrome and colour:  the images are "burnt" into the thermal paper, thu s creating a 
facsimile of the video image. This type of printer is very popular because of its ruggedness, convenie nce 
and reasonable price. Both low- and high-resolution  printers are available; 
 
b) Ink jet:  not widely used because of their limited resolutio n and colour reproduction; 
 
c) Laser: does not produce high-quality monochrome images; 
 
d) High-resolution thermal laser:  expensive and normally used for printing from stil l images; and 
 
e) Film – monochrome and colour:  the image is captured in a freeze-frame image-stor age device and 
recorded with a camera that uses a film that produc es instant photographs. The resolution and renditio n of 
the image is good. However, film that produces inst ant photography is fairly expensive. 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  6.8 Ancillary equipment  
 
6.8.1 Camera brackets  
 
Three fundamental considerations are necessary when  selecting a camera bracket, viz. weight, mounting 
plate, and mounting design. 
 
a) Weight: add the weight of the camera, lens and housing (if  used) and increase the total by 10 % to allow 
for the weight of the cabling, and select a bracket  that is designed to support this weight or more 
 
b) Mounting plate:  some brackets come with a swivel-type mounting pla te to allow the camera to be aimed 
in a variety of positions. Some come with a fixed m ounting plate, which is ideal for a wide- angle len s 
camera that is aimed in one position only. One inex pensive type comes with a ball-and- socket adjustab le 
swivel head and mounting bolt and locking ring. Sec uring the swivel head in its final position is done  by 
using an Allen key. Unfortunately, with this type o f bracket installers tend to force the head into th e correct 
position because they do not have an Allen key, and  eventually the ball and socket becomes loose and i t is 
difficult to secure the camera in the required posi tion. In addition, the camera tends to move after s et up; and 
 
c) Mounting design:  brackets are available in a variety of mounting de signs, such as wall mount, ceiling 
mount, corner mount, pole mount, and floor pedestal . 
 
Once the area or position (or both) where the camer a is to be mounted has been selected, it is fairly easy to 
select the correct bracket for the job based on the  manufacturer's data sheets, which normally include  
pictures of the various types available. 
 
6.8.2 Camera housings  
 
6.8.2.1 General  
 
Camera housings are available in a variety of shape s, sizes, and configurations and fall into two cate gories, 
viz. internal and external. Internal housings prote ct the camera and lens from tampering and are usual ly 
made of lightweight material. External housings pro tect the camera from environmental conditions, such  as 
extremes of heat, rain, dust and dirt, as well as t ampering. However, in both types of housings the le ns of 
the camera should be as close to the front glass as  possible to eliminate side view interference cause d by 
the actual housing enclosure. 
6.8.2.2 Internal housings  
The most popular type of internal housing is the st andard rectangular design, as it is inexpensive, st urdy and 
is available in many sizes and styles. Accessibilit y to the camera and lens assembly for installation and 
servicing is important and manufacturers provide on e of several means to gain access: 
a) Removable top cover; 
b) Hinged top cover; 
c) Top cover or camera and lens assembly on a slide ; 
d) Removable front or rear cover (or both); 
e) Hinged bottom cover; or 
f) Top cover on slide. 
 
A second category of popular housings is the round or hemispherical clear or tinted dome type, in whic h a 
camera, lens and an optional pan-and-tilt mechanism  are housed. Other housings include the following: 
 
a) Triangular type , which is mounted in the corner of a room or at th e intersection of two walls and the 
ceiling 
 
b) Recessed in ceiling or wall type  
 
c) Housings for covert surveillance , such as sprinkler heads, passive infrared (PIR) d etectors, wall signs 
or wall clocks; and KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  d) Speciality housings  
That can withstand high mechanical impact from hand  thrown or fired projectiles, extreme high temperat ure, 
dust, sand, liquid, and explosive gas. 
6.8.2.3 External housings  
 
External housings are often referred to as weatherp roof or environmental housings. External housings s hare 
many of the same attributes as the internal types, such as accessibility to the camera and lens assemb ly 
during installation and servicing, and vandal resis tance. The rectangular, triangular and dome-type sh apes 
are also evident. However, the main differences bet ween internal and external housings are the additio nal 
requirements that are needed from an environmental point of view. These could include 
 
a) A sun shield fitted on top of the housing in hig h-heat sunny climates, 
 
b) A heating element for extreme cold conditions or  to prevent condensation, 
 
c) Gas pressurization to prevent the ingress of dir t and dust in extremely dirty conditions, 
 
d) Washers and wipers if rain or mist is a problem,  and 
 
e) Flame and explosion protection, especially in a mining environment. 
 
Standards are used to specify the degree of protect ion provided by external housings. The rating of 
protection is given by a two-digit code prefixed by  the letters IP (index of protection). The first di git gives the 
protection rating against solid objects and the sec ond the protection rating against the ingress of wa ter or 
liquids. See annex C for index of protection rating s. 
 
6.8.3 Pan-and-tilt mechanisms  
6.8.3.1 General  
 
There are basically two camera-mount configurations  to point the camera in different directions, namel y 
panning only (or scanning in the horizontal plane),  and panning (horizontal plane) and tilting (vertic al plane). 
Most scanning units can pan through a range of 355 °, with some capable of panning a full continuous 36 0 °, 
at a typical speed of 6 ° per second. Simple scanners are used when interest  occurs in a single horizontal 
plane, such as a wide entrance to a reception lobby  area. When coverage is also required in the vertic al 
plane, a pan-and-tilt unit is used. Most pan-and-ti lt units can move through a 90 ° plane at a speed of 3 ° per 
second. Units are made for both internal and extern al use and come with a fixed-speed or variable-spee d 
capability. 
 
6.8.3.2 Mechanical considerations  
 
There are two main types of pan-and-tilt units. The  first is a unit where the camera or housing is mou nted 
direct on a platform that forms part of the constru ction – either mounted on top of the platform or mo unted on 
the side. In the second type of unit the driving co mponents are contained within the same enclosure as  the 
camera, such as a dome housing. Indoor units are ge nerally lightweight and require no environmental 
protection, and dome units are ideal for use in thi s application. External housings, however, have to contend 
with much harsher environmental conditions, such as  wind, rain, dust, dirt, corrosion, temperature ext remes, 
humidity and higher levels of vandalism. To success fully cope with these additional burdens the pan-an d-tilt 
mechanisms have to be more rugged and environmental ly resistant. It is recommended that the suppliers or 
manufacturers (or both) of such units be approached  for advice so that an appropriate unit can be sele cted 
for the application envisaged. 
 
6.8.3.3 Pan-and-tilt control systems  
 
In addition to controlling the pan-and-tilt functio n of the unit, the operator normally has the abilit y to control 
other auxiliary functions, as well as functions of the camera associated with the unit. This combinati on of a 
pan-and-tilt mechanism with camera control is norma lly referred to as a PTZ camera. 
The following functions are typical examples of the  types of control that are available: 
a) Pan; 
b) Tilt; KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  c) Zoom; 
d) Focus; 
e) Iris; 
f) Camera on/off; 
g) Preset positions; and 
h) Other auxiliary functions (heater, washers, wipe rs, etc.). 
 
There are four basic techniques that can be used to  control a remote pan/tilt-and-zoom (PTZ) unit, viz. : 
 
a) Hard-wired multicore:  this uses a multicore cable connected direct betwe en the operator's control equipment and 
the PTZ unit. Each core of the cable will carry a ded icated command signal, such as pan left, pan right, zoom in, 
zoom out, etc.;  
b) Hard-wired multiplexed:  this uses a physical twisted-pair direct connectio n. The control signals are multiplexed 
(or combined) at the control end and demultiplexed (or separated) at the PTZ camera position to provide the 
individual signals to drive the unit functions;  
c) Coaxial multiplexed:  the multiplexed signals are transmitted over the s ame coaxial cable that is used for the 
camera video signal  
d) Wireless:   the control signals are transmitted by means of n ormal RF radio techniques, or via microwave 
or infrared communication links. 
6.8.4 Screen splitter  
 
6.8.4.1  An electronic image-splitter device is a control u nit interposed between the camera (or switcher) and  
the monitor, VCR, or printer. It combines parts of the scenes of two or more cameras and displays them  on 
one monitor. The use of the inexpensive image split ter increases security in two ways: 
 
a) The screen splitter reduces the number of record ers required, since it combines several scenes onto  one 
video signal. 
 
b) It permits the operator to view a monitor with t wo or more scenes on it rather than one. 
 
6.8.4.2  The electronic or optical screen splitter takes a p art of several camera scenes and combines them 
for display on one monitor. This type of splitter d oes not compress the images and requires that the v ideo 
signals be synchronized. Whereas the majority of sp litters now use image compression techniques 
(synchronization of cameras is no longer a requirem ent) to compress and display two or more full video  
scenes on one monitor, equipment is available to co mpress 4, 9, 16, or 32 full video images onto one s ingle 
video monitor. The most common equipment in use is the quad combiner, which has four cameras; the 
complete original picture is compressed into one qu arter of its original size (half width and half hei ght). The 
resolution is likewise reduced to one-fourth of its  original. There are many features available with t his type of 
equipment and it is essential to check the manufact urer's literature for particular models. It is poss ible to 
spend more than necessary if a model is selected th at has more features than are required. Some of the  
features available are 
 
a) Electronic zoom, 
 
b) Sequential switching, 
 
c) Dual monitor outputs, 
 
d) Alarm inputs, 
 
e) Camera titling, 
 
f) loop-through switchable terminations, 
 
g) On-screen menu, and 
 
h) video-loss signal. 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
6.9 Video transmission  
 
6.9.1 General  
 
Video signal transmission is a key component in any  CCTV system. Most systems use coaxial cables, but 
optical-fibre cable is fast gaining acceptance beca use of its better picture quality (especially with colour) and 
the lower risk factor with respect to ground loops and electrical interference. Other techniques are a lso 
available, such as microwave and infrared. See anne x D for a diagrammatic representation of various vi deo 
transmission methods. A review of the principles of  operation of the various types of video transmissi on 
methods is given below. 
 
6.9.2 Coaxial cable  
 
Coaxial cable type RG59 is the most widely used vid eo transmission medium for short to medium distance s 
(that is, up to approximately 300 m). For distances  up to 900 m coaxial cable type RG11 should be used . 
These types of cable have a single conductor with a  characteristic impedance of 75 Ω, and the video signal 
is applied between the centre conductors and a coax ial braided or foil shield. Cables are available in  many 
different mechanical formats, including single-wire  armoured and irradiated PVC-sheathed cable for dir ect 
burial. Cables are also available with different pe rformance ranges, from relatively poor to excellent . 
Performance is normally measured in high-frequency loss per100 m. The lower this loss figure, the less  the 
distortion of the video signal. Therefore, higher q uality cables should be used when transmitting the signal 
over long distances. 
 
6.9.3 Twisted pair  
 
The primary purpose of using balanced twisted-pair cables is to increase transmission range and to 
eliminate the picture degradation found in some coa xial applications. Advantages of using twisted-pair  
cables include 
 
a) The ability to reject unwanted interference, 
 
b) Lower losses at high frequencies per unit length , 
c) Smaller size, 
 
d) Availability of multipair cables, and 
 
e) Lower cost. 
 
However, the advantages have to be considered in re lation to the cost of the additional equipment requ ired 
for this type of transmission. A launch amplifier t o convert the video signal at the camera end and an  
equalizing amplifier to reconstruct the signal at t he control end are needed. 
 
6.9.4 Microwave  
 
Microwave systems are radio systems that use freque ncies in the gigahertz range and therefore require an 
unobstructed line-of-sight transmission path. Any m etallic or wet objects in the transmission path cau ses 
severe attenuation and reflection, often rendering the system useless. Even when a line-of-sight path exists, 
there can be signal fading that is caused primarily  by changes in atmospheric conditions between trans mitter 
and receiver units. Normally there is one transmitt er and one receiver for each camera, which makes th is 
type of transmission system expensive. In addition,  licensing by the relevant authorities is required.  
However, when it is not possible to make a direct c able connection between the camera(s) and the contr ol 
position, and especially when real-time continuous monitoring is required, this method of video transm ission 
can be considered. 
6.9.5 Infrared radiation  
 
One of the latest methods of video transmission is the infrared link. Infrared radiation can be used t o 
transmit signals over long distances and is unaffec ted by electromagnetic interference. Although infra red 
links offer a cost-effective method of free-space t ransmission, with no licensing required, they do re quire a 
clear line of sight and are affected by adverse wea ther conditions and certain environmental condition s, 
such as smoke. 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  6.9.6 Optical fibre  
 
In optical-fibre transmission the video signal is c onverted from electrical impulses into pulses of li ght that are 
then sent down a glass optical fibre. Optical-fibre  links offer quality signal transmission, reliabili ty and 
immunity from electromagnetic interference. Optical -fibre transmitters and receivers are required to c onvert 
electrical signals into light signals and vice vers a. In addition, the optical-fibre cable has to be t erminated 
correctly to ensure optimum operation. The multiple xing of video signals with data and audio signals t hat 
travel in opposite directions simultaneously is pos sible with this method of transmission. This makes optical 
fibre very suitable for pan, tilt and zoom applicat ions. Two common types of fibres are used for CCTV 
installations, namely 
 
a) Single mode:  small in diameter, producing few reflections of li ght and used for long transmission runs of 
many kilometres, and 
 
 b) Multi-mode graded index:  larger diameter, producing many reflections of lig ht, and used extensively in 
CCTV security applications. 
 
The advantages of using an optical-fibre transmissi on system, includes the following: 
 
a) Complete electrical isolation between the camera  and related equipment from the control end, i.e. t he 
monitor, recorder, printer, etc.; 
 
b) Immunity from radio-frequency and electromagneti c induction interference; 
 
c) Inherent transmission security; 
 
d) No fire hazards; 
 
e) Absence of crosstalk; and 
 
f) No radiation of radio frequency and electromagne tic induction interference. 
 
6.9.7 Telephone network  
 
There are two main methods of transmitting speech a nd data through the Telkom telephone network, 
namely the public switched telephone system, or PST N (also referred to as PABX) and the integrated- 
services digital network, or ISDN. The fundamental difference between the two systems is that the PSTN  
uses analogue signals and the ISDN uses digital tra nsmission. The benefit of ISDN is a speed of 
transmission that is many times faster than that of  the PSTN. 
 
Reasons for using the Telkom network include the fo llowing: 
 
a) No line-of-sight requirements as in the case of infrared or microwave links; 
 
b) Distance too great for either of these methods; 
 
c) Not necessary to maintain continuous monitoring of a site; 
 
d) To remotely verify the status of a site in the e vent of an alarm; and 
 
d) To periodically "patrol" a remote site from a ce ntral station. 
 
Both PABX and ISDN require additional equipment to allow connection of the video images to the relevan t 
transmission network. This equipment is needed to c onvert the video signal into digital information, t o 
transmit and receive the digital signals and then t o convert the digital information back to the video  format at 
the receiving end. It is even possible to control p an-and-tilt cameras over the same networks using si milar 
transmission techniques. 
 
 
 
6.9.8 Selection of appropriate video transmission s ystem  
 
6.9.8.1  The most economical and most common method of video  transmission is by coaxial cable. Owing to KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  cable characteristics, the higher frequencies are a ttenuated (video signal loss) and it might be neces sary to 
install equalizing equipment to restore resolution and contrast on long lengths of cable. In addition,  it might 
also be necessary to provide a video amplifier to b oost the video signal level when the distance excee ds the 
recommended cable length. This amplifier is normall y installed at the camera location. As an alternati ve to 
using coaxial cables on long runs, balanced twisted -pair cables can be used quite successfully. 
 
6.9.8.2  In applications where the running of cables is not desirable or feasible and a line-of-sight path is 
present, an infrared or microwave system may be use d. Different models are available based on cost, pa th 
distance and frequency band. In most instances a li cence will also be required. 
 
If a cable can be used and coaxial cable is not a g ood choice owing to distance, conduit space, interf erence, 
ground loops, or security-signal concerns, a multi- mode graded index optical-fibre cable transmission 
system can be used. Optical-fibre equipment is cost -sensitive to the distance and each transmission pa th 
should be analysed to optimize the design. 
 
When visual verification of an alarm initiated from  a remote site is required or "remote" CCTV patrol of a site, 
or when the distance between the camera system and the monitors and control equipment is very great, t he 
existing telecommunication telephone network can be  used. 
 
7 Lighting considerations  
 
7.1 General  
 
Ambient light, by itself, is not sufficient to prov ide adequate illumination for exterior video assess ment for 
other than low-light-level cameras, such as the sil icone intensified target (SIT) or intensified CCD ( ICCD) 
types of camera. These cameras operate at significa ntly lower light levels than the best tube or solid -state 
cameras. Any intensified camera is expensive and sh ould only be considered for critical security 
applications. Therefore, the following lighting inf ormation is based on CCTV installations that use st andard 
types of video camera. Technical information in res pect of specialized low-light-level cameras can be 
obtained from the relevant manufacturer or supplier . 
 
7.2 Lighting requirements  
 
Four important requirements should be considered wh en a lighting system for a typical CCTV installatio n is 
designed, namely horizontal luminance, vertical lum inance, uniformity ratio, and lighting spectrum. 
 
a) Horizontal luminance , i.e. the light incident on a horizontal plane: th e intensity of this light has to be 
sufficient to provide adequate face-plate illuminat ion to the camera. This is a function of not only t he camera 
sensor device but of also lens speed (the f-number) , lens quality and scene reflectance. This relation ship 
can be expressed by the following equation: 
 
Is = 4 × Ifp × f2 
    R ×TR  
Where 
 
Is    is the scene luminance, expressed in lux (see note 1);  
Ifp        is the sensor face-plate luminance, expressed in lu x; 
f        is the lens f-number;  
R       is the reflectance of the scene, expressed as a per centage (see note 2);  
 
TR  is the lens transparency ratio (or efficiency) (see  note 3). 
 
NOTE 1 :Table 3 lists some typical lighting levels found in various environments. These levels should be considered as a guide only 
and are not definitive in any way. Actual light lev els should always be checked (by using a light mete r), including the variation from the 
lightest to the darkest. In contrast to these artif icial light source levels, natural lighting levels range from 100 000 lx for bright sun to 
0.0001 lx for clear starlight. 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  NOTE 2: A camera only sees light reflected back to it from the subject of the scene. Only an optically  perfect mirror will reflect back 100 
% of the light that shines on it. Anything else is comparatively poor at reflecting light. When light strikes a scene or an object, some is 
absorbed, some is diffused in scattered directions and some is reflected back to the camera. The amoun t of light reflected back to the 
camera is defined as a percentage of the light that  illuminates the subject. This is the reflectance o f the scene. Some typical values are 
given in table 4. 
 
NOTE 3: The lens f-number (or f-stop) is simply a ratio of the focal length to the  effective diameter of the lens and although it is the 
measure of the amount of light that the lens will p ass, it is not a measure of the quality or efficien cy of the lens. The measure of 
efficiency of the lens is known as the transparency  ratio and would typically be 0,85 for a high- qual ity lens and 0,6 for a cheaper lens. 
 
b) Vertical luminance:  this is the light incident on the vertical plane. This light has to be intense enough to 
provide good contrast between an object in the scen e and the background. The required lighting level i s 
difficult to estimate; however, for most exterior l ighting systems that satisfy the horizontal illumin ation 
requirements, vertical luminance is at an adequate level. 
 
c) Uniformity ratio:  equal in importance to luminance levels, but often  not considered, is the ratio of the 
highest luminance to the lowest luminance in the sc ene. If the light/dark ratio is excessive, lighter areas will 
provide too much light, causing blooming or wash-ou t of details. Likewise, the darker areas will not p rovide 
sufficient light for good resolution. As a general rule of thumb, the uniformity ratio for external li ghting should 
be less than 5:1. This includes the entire area obs erved by the cameras and not just the area of inter est, i.e. 
lighting has to extend beyond corners and fences to  provide even illumination over the full field-of-v iew of 
the camera. 
 
d) Lighting spectrum:  camera image devices are similar to the human eye in that they are sensitive to only 
a limited band of the electromagnetic spectrum. If the light-output spectrum and the camera imaging de vice 
spectrum sensitivity are different, more light migh t be required to provide adequate illumination. 
 
           Table 3- Luminance in typical environmen ts 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 2 3 
Environment Type Luminance lx 
Manufacturing Assembly 
 
 
 
Banks 
 
 
General buildings 
 
 
 
Hospitals 
 
 
 
Manufacturing inspection 
 
 
 
Offices 
 
 
Hotels 
 
 
 
Parking areas 
 
 
Retail stores 
 
 
Warehousing Rough 
Medium 
Fine 
 
Lobby 
Office and cages 
 
Dining rooms 
Halls and corridors 
Outdoor entrance 
 
General Surgery 
Operating table 
Examination table 
 
Rough 
Medium 
Fine 
 
General 
Accounts 
 
Bars 
Restaurants 
Kitchens 
 
Outdoor night 
Garage 
 
Small 
Large 
 
Good lighting 
 200 
500 
1000 
 
200 
500 
 
100 
150 
30 
 
500 
18000 
500 
 
200 
500 
1000 
 
500 
750 
 
150 
100 
500 
 
10 
50 
 
200 
500 
 
100 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
Table 4- Reflectance of common materials 
 
1 2 
Scene Material Reflectivity a 
% 
White plaster 
Snow 
Glass windows and walls 
White matt paint on concrete 
Unpainted concrete 
Parking area with vehicles 
Red brickwork 
Open country, trees, grass, etc. 
Empty asphalt area 
Clothes 
Human face 90 
85 
70 
60 
40 
40 
35 
20 
5 
15-30 
15-25 
a Within the visible spectrum: 380 nm to 780 nm.  
 
 
7.3 Beam angle  
 
Another important characteristic when determining t he amount of light that reaches a scene, is the bea m 
angle over which the light source radiates. Light s ources are classified by their light-beam pattern. This can 
range from a narrow beam of a few degrees, to a wid e beam of 30 ° to 90 °. It is best to match the camera-
lens field of view to the light-beam radiation patt ern in order to obtain the best uniformity of illum ination over 
the scene. If a large area is to be viewed, either a single wide-beam source or multiple sources have to be 
located within the scene to illuminate it fully and  uniformly. Most lighting manufacturers can provide  the 
coefficient of utilization (CU) for a specific lumi naire. 
 
7.4 Spectral characteristics  
 
Every natural and artificial light source has a uni que output spectrum of colours, which might or migh t not  
be advantageous to a particular camera. Monochrome (or black-and-white) cameras for the most part 
cannot perceive the colour distribution or spectrum  of colours from different light sources. The pictu re 
quality of most monochrome systems depends solely o n the total amount of energy emitted from the lamp 
source, i.e. energy that the camera is sensitive to . For a colour camera to see all the colours in the  visible 
spectrum, the light source has to contain all the c olours of the spectrum. To obtain a good colour bal ance, 
the illumination source should match the sensitivit y of the sensor device. Broadband light sources, su ch as 
tungsten, tungsten halogen and xenon, produce the b est colour images because they contain all the 
colours in the spectrum. Narrow-band light sources,  such as mercury-arc or sodium-vapour lamps, do not  
produce a continuous spectrum of colours, with the result that colour is rendered poorly. A mercury la mp 
has little red output, and therefore red objects ap pear nearly black when illuminated by this type of lamp. 
Likewise, a high-pressure sodium lamp contains larg e quantities of yellow, orange, and red light. So a  blue 
or blue/green object will appear dark grey or brown  in this light. A low-pressure sodium lamp produces  only 
yellow light and is consequently unsuitable for col our CCTV. Spectral characteristics of lamps and cam era 
imaging devices are given in figure 1 and a summary  of typical lamp types and their suitability for us e with 
monochrome or colour cameras (or both) is given in table 5. 
 
 
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1 — Spectral characteristics of lamps and ca mera imaging devices  
 
 
 
Table 5- Lamp type and camera suitabilty 
 
1 2 3 
 
 
Lamp type 
 
  
Suitability 
Monochrome Colour 
Tungsten 
Tungsten-halogen 
Xenon 
HID-Mercury 
       -Metal Halide 
       - High –pressure sodium 
Low- pressure sodium 
Fluorescent 
Compact fluorescent (CFL) Yes 
Yes 
Yes 
Yes 
Yes 
Yes 
Yes 
Yes 
Yes 
 Yes 
Yes 
Yes 
N o 
Yes 
No 
No 
Yes 
Yes 
 
 
 
 
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
 
7.5 Infrared illumination  
7.5.1 General  
 
There are many situations where it is not practicab le or desirable to provide adequate lighting levels  by 
conventional methods. It could be that the camera o bserves large areas that are impracticable to illum inate. 
In other situations the presence of the illuminatio n might have to be discreet, for example when the 
presence of a security system would attract unwante d attention, would alert intruders to the CCTV syst em, 
or could disturb neighbours on adjacent properties.  In these instances the necessary illumination coul d be 
provided by a covert infrared lighting system. Typi cally an infrared lamp is fitted with a tungsten fi lament 
bulb, as the filament burns at a higher temperature  and emits more light. The bulb is mounted in a spe cial 
housing that has a toughened glass filter fitted at  the front. The colour of the filter determines wha t 
wavelengths of light can be passed. The common wave lengths used in CCTV systems are 715 nm, 780 
nm, 830 nm and 850 nm. As the visible part of the s pectrum goes to approximately 780 nm, lamps with a 
715 nm filter will show a dull red light. Lamps wit h emissions above 780 nm will show no visible light  and 
are known as black lamps. 
 
7.5.2 Power output of infrared lamps  
 
Lamps are available in a wide range of power output s, from 50 W to 500 W, the most common being the 
types in the range 300 W to 500 W. These lamps tend  to produce a considerable amount of heat, which is  
wasted energy owing to the inefficiency of the refl ector in reflecting the infrared energy. The life o f the bulbs 
is also short, which makes this type of illuminatio n fairly expensive. There are infrared lamps on the  market 
that are far more efficient than the traditional de sign. These are usually fitted with miniature bulbs  that 
operate on 12 V d.c. and have special gold-plated r eflectors that reflect much more of the infrared sp ectrum 
forward, thus resulting in less heat loss. These la mps range from 20 W to 300 W and can be of the spot  
type, medium-angle type or wide-angle type. The bul b is twice as efficient in the transmission of infr ared 
light. Thus, a 200 W special bulb will give out an illumination level equivalent to a 400 W standard b ulb. 
 
7.5.3 Infrared lamp data  
 
Camera manufacturers give data on sensitivity in lu x (which is a measure of visible light) and therefo re it is 
not easy to calculate the required illumination lev els for a CCTV system when an infrared lighting sch eme 
is designed. Two important factors have to be consi dered, namely the efficiency of the reflector (and hence 
the resultant energy loss), and the fact that many lamps are run at a voltage below their rated value to 
provide a longer life. It is recommended that guida nce be obtained from the relevant lamp manufacturer in 
respect of data such as the intensity of the light source, the angle of the  beam, expected light levels at various 
distances from the light source, the design of refl ector and the  type of lamp to be used. Even with good input from t his 
expert source, tests on site are often the only  way to be sure that the lighting design is effecti ve. 
 
7.5.4 Dual-camera technology  
 
Since no visible light is present under infrared il lumination, only monochrome images can be seen. If 
monochrome cameras are being used for daylight obse rvation, they can also be used when infrared 
lighting is used. However, if colour cameras are be ing used under daylight conditions, additional 
monochrome cameras would be required to observe the  same scene if infrared lighting is being used. To 
overcome this limitation, several camera manufactur ers offer a dual camera that provides high- resolut ion 
colour images, even in low-ambient-light-level cond itions, and the ability to switch either manually o r 
automatically to high-resolution monochrome operati on when the camera is used with infrared lighting. 
 
7.5.5 Alternative illumination technique  
 
A new generation of devices composed of an array of  gallium arsenide (GaAs) semiconductor diodes that 
emit a narrow band of infrared radiation and no vis ible light is being used for covert security survei llance. 
These devices are very efficient and operate just a bove room temperature. Since they dissipate little heat, 
they require no special cooling considerations. The  output power from each diode adds linearly, with t he 
sum total illuminating the target scene with suffic ient infrared energy to produce good quality CCTV i mages 
with solid-state or tube cameras. Generally, severa l hundred diodes (mounted on a plane) are required to 
illuminate a CCTV scene. At present, this method of  illumination is being used for interior covert 
surveillance, although it is not yet in general use . 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  7.6 Lighting design considerations  
 
The initial step to be taken when designing a light ing system for use with CCTV cameras is to determin e 
the level of lighting required. Once this requireme nt has been determined, manufacturers and suppliers  of 
lighting equipment can be consulted in terms of the  actual design. Many of the larger suppliers have a ccess 
to computer programmes that can model suitable ligh ting systems. Factors that will determine a cost-
effective design will include initial installation costs, operating costs (energy usage), maintenance costs 
(such as lamp life and labour costs), and the secur ity risk due to the unavailability of adequate ligh ting. 
 
Initial installation costs are lowest for incandesc ent lighting, followed by fluorescent lighting and then high-
intensity-density (HID) lamps. Generally, there is a significant saving in operational costs (energy c osts) 
between the high-pressure sodium and fluorescent la mps as compared with the mercury vapour and 
standard incandescent lamps. High-pressure and low- pressure sodium lamps and the HID mercury vapour 
lamps have a much longer lamp life than the incande scent types, which are relatively low. The lamp lif e of 
fluorescent lamps lies between these two extremes. If changing lamps is inconvenient or costly, high-
pressure sodium should be used in place of incandes cent types wherever possible. Data with respect to 
the installation, operating and maintenance costs c an be obtained from the relevant manufacturers or 
suppliers of the particular lamps being considered.  
 
If possible, a final lighting configuration should be tested by the installation of a minimum of 10 fi xtures for 
actual measurement and hence evaluation of the desi gn. Adjustment and modification of the total lighti ng 
system after installation should be anticipated, as  it is not uncommon to discover during camera testi ng that 
there are spurious reflections, bright spots, etc. that have to be corrected. 
 
8 Control-point configurations  
 
8.1 General  
 
The effective operation of any CCTV system will dep end on the operator, i.e. from the simplest system,  in 
which the operator could well perform other functio ns (for example, the small retailer), to the most 
sophisticated system, in which dedicated operators are employed. However, in both instances the operat or 
will have to respond when something unusual occurs.  Operating knowledge is therefore required by any 
type of CCTV system operator. In large CCTV systems  it is essential that suitable working conditions b e 
provided in order to maximize operator performance and minimize human failure. This section will deal with 
those key issues that should be addressed when desi gning a control room for a major CCTV system. 
However, the recommendations can also be adopted wi th suitable modifications for use when smaller 
control rooms are being designed. 
 
8.2 Operational considerations  
 
8.2.1 General  
 
While the system equipment may perform optimally, a ny failure on the operator’s part will lead to a pe rformance 
degradation of the entire CCTV scheme. Key issues tha t need attention are job design, equipment design, picture 
formatting, and the layout design of the actual mon itoring environment.  
 
8.2.2 Job design  
 
The job design of a CCTV operator should be develop ed around four distinct areas, namely 
 
a) Definition of what the surveillance system shoul d be looking at (that is, what you want the operato r to 
look at or look for), 
 
b) Definition of how surveillance should be carried  out in order to heighten the attention span and in crease 
sensitivity towards potential incidents, 
 
c) A description of what indicators the operator sh ould tune into in order to recognize incidents in p rogress,  
 
d) Definition of how the operator's performance is to be measured; this will be aimed at motivating 
operators, diagnosing performance issues and proble ms, and identifying development needs of both the 
operator and the system. KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
A review and amendment of the operator’s job descri ption could also result from a change in any of the  
above-mentioned four areas. 
 
8.2.3 Equipment design  
 
Monitors should be easy to view and control panels should be simple and straightforward to use. Althou gh 
it may sound obvious, all too often switches all lo ok the same, legends are too small and joystick con trols 
are unprotected and easy to inadvertently disturb. Designers of these control panels also frequently f orget 
that they have to be used under stressful condition s or in reduced lighting. Therefore, the design sho uld 
allow for visible legends with keys laid out for ea sy and quick execution of the functions. 
 
 
Video monitors are a critical interface between the  camera and the operator. It is therefore pointless  to use 
sophisticated camera technology if the quality of t he picture on the screen is reduced by a poor- qual ity 
monitor. Poor visual recognition and operator fatig ue is reason enough to provide good quality monitor s. 
 
8.2.4 Picture formatting  
 
All too often operators are faced with an unstructu red bank of pictures where the actual order of imag es 
can relate to something as arbitrary as camera numb er or the arrangement left by a previous operator. It is 
essential to rationalize and structure the visual i nformation. Monitors grouped by site location or 
predetermined routines of camera observation will m ake it easier to detect changes. A well thought-out  
arrangement can also pre-alert the operator to the action required when an incident is detected. 
 
8.2.5 Monitoring environment  
 
8.2.5.1 Monitor positioning  
 
The traditional console is giving way to desktop ar rangements. The benefits of these arrangements are flexibility, 
accessibility and easier replacement of monitors. T he main problem with this approach is the use of mu ltiple monitors 
and still having sufficient desktop space for contr ol operations. Monitor banks provide a general over view that can then 
be followed up on a primary monitor for incident detection. This monitor will be provided directly i n front of the 
operator.  
 
When a console is used, it is normal to place the m onitor bank well above the operator's eye level. Th e 
need to operate controls and communication devices while staring upwards is physically uncomfortable a nd 
is disliked by operators for this very reason. It t ypically leads to the operator moving away from the  console 
and leaning back in order to view the screens, with  the concomitant negative implications for viewing clarity 
and access to controls. Should this method of insta llation be necessary, it is recommended that the 
monitors be placed no more than 25 degrees above th e straight viewing plane of the operator. 
8.2.5.2 Number of monitors  
 
The depth at which targets appear in the video imag e has an influence on detection rates, and with mor e 
monitors observers are less likely to detect target s at greater depths within the image. This indicate s that 
the greater the risk and the more subtle the behavi our to be detected, the fewer monitors should be us ed. It 
is recommended that no more than five monitors be u sed for one operator. 
8.2.5.3 Camera display handling  
 
In an attempt to control the amount of information coming to the operator from cameras via monitors a 
number of solutions are possible. The simultaneous display of multiplexed images on a single monitor 
allows greater coverage but leads to major deterior ation in image clarity. In high-risk situations whe re visual 
clarification is necessary this option is not recom mended. Another alternative is the auto cycling of images 
from different cameras, where the image on screen i s replaced every few seconds by one from another 
camera. However, critical images could be missed ow ing to the auto cycling sequence. The detection of 
movement by peripheral vision is best achieved with  fixed or static pictures and auto cycling is likel y to 
negate this ability. 
 
The most effective method of directing multiple-cam era information through to a single monitor is the use of 
blank-screen technology, but this is effectively li mited to alarm-type conditions, where the screen ac tivates 
in response to an alarm input or the movement or pr esence of a person in a particular location. The us e of 
blank-screen technology, while useful, is also cont entious in terms of positioning. Having blank scree ns KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  alongside the primary monitor is not only distracti ng but causes visual discomfort for the operator. 
 
 
8.2.5.4 Seating design  
 
Seating design should ensure comfortable and access ible access to the operator’s work station, includi ng 
reach distance to the control apparatus, under-coun ter leg space, and angle-of-sight to monitors. The use 
of chairs that are mobile and offer a reclining pos ition are preferred. 
 
When using 14 inch monitor screens it is recommende d that the viewing distance be between 0,5 m and a 
maximum of 2 m. Larger monitors allow more flexibil ity in distance and are therefore recommended for 
monitoring tasks. 
 
8.3 Control-room layout  
 
Poor control-room layout can undermine the investme nt put into high-grade CCTV systems. For example, i f 
the screens cannot be seen properly, efficiency wil l be compromised. Selecting the right shape and siz e of 
room can go a long way to ensuring that a workable layout can be achieved. If possible, rooms that are  
square and allow for approximately 10 m of space pe r operator should be  selected. Rooms with pillars or 
with strongly angled walls should be avoided. There  is ample evidence that people do not like working in 
windowless environments, from a psychological point  of view. Therefore, it is recommended that windows  
be included in the design of the control room. Such  windows do not have to be large or directly in fro nt of 
the operator; they should allow operators some cont act with the outside world in terms of whether it’s  
sunny, raining or dark. In addition windows should not be so situated as to cause on-screen reflection s. 
Blinds or other screening methods for the windows s hould be available. 
 
The control room will also be associated with other  space facilities, such as an equipment room, a vid eo 
review room, toilets, kitchen and a rest area. Acce ss into the control, equipment and review rooms has  to 
be strictly controlled to prevent unauthorized entr y. 
 
8.4 Environmental considerations  
 
8.4.1 General  
 
Concentration, screen visibility and hearing voice communications can all be linked to such environmen tal 
factors as room temperature, air movement, lighting  and ambient noise levels over which the designer h as 
some control. 
 
8.4.2 Room temperature and air movement  
 
Hot, stuffy rooms are not conducive to keeping oper ators alert. Avoidance of excessively high 
temperatures, the maintenance of adequate airflows and a good quantity of fresh air can do much to kee p 
operators alert. Air temperatures should be increas ed in the early hours of the morning when the human  
body temperature drops. 
 
8.4.3 Lighting  
 
The best current practice for CCTV control rooms is  the use of indirect lighting. With these schemes t he 
light sources are shone onto the ceiling with the r eflected component providing the working light sour ce, 
which is largely glare-free, soft and shadow-less i llumination. Down lighting, which gives a balanced 
illumination with a dimmable capability within the range 50 lx to 300 lx on the work surface, is also 
acceptable. 
 
8.4.4 Ambient noise  
 
Controlling noise at source is preferred, such as u sing hoods over noisy printers. However, by careful  
specification of interior room finishes, ambient no ise can be reduced to acceptable levels. Suppressio n of 
noise frequencies that are known to interfere or ma sk voice communication can also be introduced. 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  8.5 Operator selection and training  
 
It has been traditional in many service industries to put those members of the staff who can no longer  
perform their normal jobs satisfactorily into the c ontrol room. Fortunately, it has now been recognize d that 
proper selection and training of control-room opera ting staff is considered essential if the control f unction is 
not to become the weak link. 
 
Some of the selection factors that have to be taken  into account when an applicant is being considered  for 
a control-room post should include an ability to wo rk under pressure, vigilance capabilities and the a bility to 
perform under widely fluctuating work levels. 
 
Training should be so designed as to ensure that op erators become fully conversant with the use of all  
items of equipment and be able to deal with any ope rational circumstances that might confront them. 
Coping with equipment malfunction and novel situati ons should form an integral part of such training 
programmes. The use of simulation techniques and ro le playing can be used, as well the more traditiona l 
approach of having a trainee sitting alongside an e xperienced operator to learn the necessary skills. 
 
9 Power supply considerations  
 
9.1 Power sources  
 
CCTV equipment operates from either an alternating current (a.c.) or a direct current (D.C.) power sou rce. 
The power source type and voltage level used depend s on the equipment chosen and the intended 
application. By far the most convenient power sourc e available for CCTV equipment is the mains supply.  
When it is necessary to locate equipment remote fro m the power source, it is often convenient to use a .c. 
equipment that operates on 24 V obtained through a step-down transformer. The main advantage of using 
a 24 V a.c. power source, apart from the obvious sa fety reasons, is that the power source can be fitte d by 
anyone and a qualified electrician (that is, one ho lding a wiremans' licence) is not required. If equi pment is 
designed for use with a D.C. power source, such as some CCD cameras or small covert type cameras, a 
12 V D.C. power source is used. One such power supp ly per camera is needed. This supply can be derived  
from an a.c. source that uses an a.c.-to-d.c. conve rter or power supply, or from a battery. 
 
To protect the CCTV equipment from external, delete rious electrical noise, surge protectors or power 
conditioning equipment is used. 
 
9.2 Power supply problems  
 
9.2.1 General  
 
Power supply problems can be defined as any irregul arity, disturbance or interruption that is induced in or 
that occurs along a power line. These problems rang e from microsecond faults, voltage dips and surges,  
line spikes and brownouts, to common electrical noi se and line-frequency harmonics. Although the power  
generated by the power utility (such as Eskom) is c losely regulated with regard to amplitude and frequ ency, 
voltage distortions and disturbances can and do occ ur. 
 
9.2.2 Voltage surges  
 
A voltage surge is a temporary rise in amplitude th at usually lasts at least one half cycles (1/100 se cond). 
This type of disturbance is usually caused when hig h-powered electrical equipment is switched off. 
 
9.2.3 Voltage spikes  
 
When lightning strikes a power line or the ground n earby, a large, damaging voltage pulse can enter 
electronic equipment and destroy everything in its path. While the spike might last only a few millise conds, 
it can reach thousands of volts. 
 
9.2.4 Voltage dips  
 
A voltage dip is the opposite of a voltage surge. D uring a voltage dip, the line voltage decreases for  a short 
period that lasts at least one half cycle (1/100 se cond). Dips are usually caused by a sudden increase  in 
electrical load or dissipated power. 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  9.2.5 Brownouts  
 
During periods of unusually high power demand the p ower utility might be forced to reduce the line vol tage 
by up to 15 %. This has the same effect as a prolon ged voltage dip and can create many forms of 
abnormal behaviour and equipment failure. 
 
9.2.6 Blackouts  
 
The ultimate power problem is a blackout, when the power is lost completely and the equipment that rel ies 
on it ceases to operate. 
 
9.2.7 Electrical noise  
 
Electrical noise is generated by such items as ligh tning, radio transmitters, poor brush contacts on d .c. 
motors and many other electronic devices that have switching power supplies. Electrical noise disrupts  the 
smooth sinusoidal power-line voltage and adds many sharp-edged, high-frequency voltage changes. 
 
9.2.8 Power conditioning equipment  
 
9.2.8.1 General  
 
Preferably, owing to the above potential problems, video equipment and other sensitive electronic devi ces 
should not be connected direct to the raw power sou rce. If at all possible (cost is normally a limitin g factor), 
power-line conditioning and filtering equipment sho uld be provided as part of the power distribution d esign. 
This will provide a source of continuous uninterrup ted power at all times, including during complete 
blackouts. This is especially important when a CCTV  system is used in a high-rise area or where 
continuous surveillance is essential. 
 
9.2.8.2 Uninterruptible power supplies  
 
Uninterruptible power supply (UPS) equipment is cat egorized by output power capacity and generally 
configured for continuous duty or standby operation . In the first type, power is supplied continuously  to the 
load by a device called a static converter, which o btains its power from a storage battery. The batter y 
charges itself continuously through the incoming po wer line. 
 
 
Traditional types of UPS systems simply convert the  incoming a.c. power to d.c. by using rectifier and  
charging equipment, to charge a bank of batteries a nd provide direct current to a d.c.-to-a.c. convert er that, 
in turn, provides the a.c. power to the electronic equipment. Unfortunately this type of UPS system is  prone 
to failure and its conversion efficiency rate is fa irly low (in some cases as low as 60 %of original p ower 
input). To overcome these shortcomings, constant-vo ltage ferro-resonant trans- former and sophisticate d 
line-sensing equipment were added to modern UPS des igns. This transformer cleans up the raw line 
power, which eliminates spikes, dips, surges, noise  and minor brownouts or drops in voltage. In additi on to 
this power conditioning effect, the efficiency of t he UPS system increases to 90 %, a higher reliabili ty is 
achieved, cost savings can be obtained (the design is simpler and smaller), and owing to the transform er's 
so-called "flywheel effect" no break in the supply output voltage is detected by the electronic equipm ent. 
 
A decision has to be made, preferably when the oper ational requirements are being determined, as to 
whether the proposed CCTV system has any essential camera, monitor or recording equipment that has to 
continue operating in the event of a power failure.  If so, a UPS system has to be provided. It is 
recommended that the design of this type of system be carried out by a qualified electrical engineer. 
 
9.2.8.3 Lightning and surge protection devices  
 
Surges can enter electronic equipment through the p ower or through the signal cables (or both). Since it is 
easy to identify the points of surge entry, the loc ation for the fitting of surge protective devices ( SPDs) can 
also be easily ascertained. The only question is th e type of device that should be provided. Metal-oxi de 
varistors (MOVs) are quite adequate for the protect ion of the mains-connected equipment. However, 
electronics are characterized by a small difference  between the normal circuit operating voltage and t he 
voltage capable of causing damage, and therefore th e protection device has to clamp the voltage betwee n 
the signal lines and the signal reference conductor . For this reason, the sharper knee characteristic of the 
silicon suppressor is used. 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  The problem with this type of suppressor is its lim ited surge energy absorption capability. Additional  
components are therefore required in the form of a spark-gap device and a series-impedance device. The  
function of the impedance is to limit the current t hrough the silicon suppressor both before the spark  gap 
has operated (the spark gap does not operate instan taneously owing to inherent delays in the creation of 
the arc; this delay could be microseconds) and afte r the spark gap has operated (the arc voltage can b e as 
much as 30 V). 
 
Ideally, the spark gap device should be located at the building entrance where both the cable entry po int 
and the earth bar are situated. The advantages of t his position are that the surge currents are divert ed as 
soon as possible and that the large-magnitude magne tic fields associated with the surge current are ke pt 
away from the sensitive electronic equipment. For m any situations this spark-gap position is not feasi ble 
and therefore the closest protective earth is used.  
 
Typically, the mains electrical network should be p rotected at the first point of entry of the cable b y a 40 kA 
3-phase and neutral surge protective device (SPD). Any distribution board more than 10 m from the firs t 
point of entry should also have the 40 kA SPD for 3 -phase and neutral installed or a 40 kA SPD for sin gle 
phase and neutral. If the distribution boards are l ess than 10 m from the mains supply, a 6,5 kA SPD f or 3-
phase or single phase and neutral will be sufficien t. The SPD used to protect the electronic equipment  will 
depend on the type of inputs into the equipment, su ch as telephone lines, antenna cables, or other inp ut 
types. Lightning and surge protection is a speciali zed area of expertise and it is recommended that th e 
appropriate individuals or companies (or both) that  are proficient in this type of protection be appro ached 
for design assistance. 
 
9.3 Power distribution  
 
9.3.1 General  
 
The primary function of the power distribution syst em is to provide the path for the required power to  reach 
the CCTV equipment. All wires and cables associated  with the distribution network have to have the 
insulation, voltage breakdown and physical characte ristics suitable for the voltage, current, power an d 
environment in which they will be used. In addition  they have to meet the fire and safety standards of  the 
local authority. 
 
9.3.2 Distribution techniques  
 
When a single item of equipment is connected to the  power-supply output, the conductor size, i.e. the wire 
diameter, has to be sufficiently large so that no s ignificant voltage drop occurs between the power su pply 
and the equipment that could result in too low a vo ltage being available at the equipment. By specifyi ng the 
correct conductor size based on the actual distance  from the power source to the equipment and the 
amount of current the equipment requires, the volta ge drop will be minimized. It is normal practice to  
connect equipment in parallel across the power sour ce. If this is the case, it is important to ensure that the 
equipment at the end of the power line receives the  minimum rated voltage for that particular item of 
equipment. 
 
9.3.3 Safety aspects  
 
Most electronic equipment functions with two generi c cable types, namely signal (and control) and powe r. 
For safety reasons and to keep extraneous noise fro m contaminating signals, these two cable types shou ld 
not run close to each other. In fact the electrical  power cables should be run in a separate conduit o r 
trunking from the signal cables. The reason for thi s is that the power cables are manufactured with 
insulation resistance sufficient to withstand the h igher voltages used in power systems, whereas the s ignal 
cables usually have insulation sufficient for volta ges up to approximately 100 V. Thus the physical 
separation of the two types of cable will prevent a ccidental shorting that could lead to the injury or  death of 
a person handling the signal cable (which could be in dangerous contact with the power cable), or shor ting 
that could lead to sparks and possibly the outbreak  of a fire. 
 
9.3.4 Earth loops  
 
Another important aspect of the electrical distribu tion system is the use of good earthing practices a nd the 
elimination or avoidance of earth loops in the syst em, where earth loops can be considered as the 
undesirable current paths that connect together ear thed points, equipment earth points or signal-retur n 
connections. The finite resistance, inductance and capacitance of conductors that carry these earth-lo op 
currents provide a common cross-coupling impedance to inject unwanted signals, noise, and crosstalk in to KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  sensitive input circuits. 
 
The optimum configuration can only be determined af ter a thorough analysis of the distribution system,  as 
well as of the equipment chassis and power-line ear thing. Most electronic equipment is so designed tha t 
electronic circuitry is earthed at one or more poin ts on the equipment chassis. The system should be s o 
designed that these earth points are connected elec trically with a good conductive path from each piec e of 
equipment to the next, and to the earth point of th e power distribution grid. 
 
To achieve noise-free CCTV image performance the fo llowing practices are recommended: 
 
a) Ensure that proper earthing is in place. 
 
b) Co-axial cables should be terminated at both end s. 
 
c) Equipment chassis and cable shields should never  be used for signal-return paths, with the exceptio n of 
co-axial cables. 
 
d) Signal circuits should use balanced cable, such as twisted pairs or shielded or balanced co-axial l ines. 
 
e) Individual shields of balanced co-axial cables, when contained by a common shield, should be insula ted 
from one another and from the common shield. 
 
f) Cables that carry high-level signals should not be bundled with cables that carry low-level signals , 
whether shielded or not. 
 
g) Each signal cable should have its own independen t return line running as close as possible to the s ignal 
line, thus reducing the loop area. 
 
h) Use twisted-pair cable (signal and return lines together) to ensure a minimum pickup-loop area. 
 
10 Functional and operating procedures  
 
Functional and operating procedures for the CCTV sy stem should be indexed to facilitate easy reference 
and include the following:  
 
a) An overview of the complete CCTV system, including  an equipment block schematic and a cabling and wiring 
schematic; 
 
b) The manufacturers' technical specifications for each item of equipment that comprises the CCTV 
system; 
 
c) The functions and features of each item of equip ment; 
 
d) Individual operating instructions for each item of equipment; and 
 
e) Detailed operating instructions for all modes of  operation of the CCTV system. 
 
11 Enquiry documentation  
 
It is usual, especially for large CCTV projects, to  issue a tender enquiry. This enables contractors w ho are 
considered suitable to undertake the required work to bid in a competitive manner for the project in t erms of 
specified performance and functionality requirement s as well as price. This enquiry documentation woul d 
normally (but not always, as it depends on the size  of the CCTV system to be installed) contain the 
following sections: 
 
a) The invitation to tender: this would contain the  invitation, provide a brief description of the wor ks and give 
the tender return information, such as the return a ddress and the closing time and closing date of the  
tender; 
 
b) Contract data: e.g. location of the works, clien t details, contractor's details, important contract ual dates; 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  c) General conditions of contract: the general cond itions under which the contract will be executed; 
 
d) Special conditions of contract: these are the sp ecial conditions (if any) that apply to a particula r project or 
installation that do not fall within the normal sco pe of the general conditions; 
 
e) Works information: this will provide a complete description of the work to be performed, i.e. the w here, 
the what and the how, etc.; 
 
f) Technical specification: this would include gene ral technical requirements and equipment or system 
specifications (or both); more details in respect o f this specific aspect are given in clause 12; 
 
g) Bills of quantities: this will provide a list of  the items and quantities of equipment required; th e tenderers 
will price against this document; and 
 
h) Other relevant documentation: this could include  insurance requirements, performance guarantees, si te 
and equipment layout drawings, and any other inform ation deemed necessary. 
 
12 Technical specifications  
 
12.1 General requirements  
 
The technical specification document should include  some or all of the following sections: 
 
a) Regulations under which the installation should be erected and tested; 
 
b) Installation codes of practice that apply; 
 
c) Material, equipment and workmanship conformance standards that apply; 
 
d) Operator training that is required; 
 
e) Maintenance tools and equipment to be supplied a s part of the installation; 
 
f) Storage of equipment and materials on site; 
 
g) Co-operation with other trades that might be nec essary during the installation process; 
 
h) Supply and control of drawings; 
 
i) Maintenance requirements during guarantee period ; 
 
j) Documentation requirements in terms of operating  and maintenance manuals; and 
 
k) Any other issue that has to be specified. 
 
12.2 Equipment specifications  
 
NOTE :When drawing up a technical specification, it  is recommended that the following minimum equipmen t 
Considerations be applied. This list is not exhaust ive. 
12.2.1 Cameras and lenses  
 
12.2.1.1 General  
 
CCTV cameras should 
 
a) Be of high quality from a reputable supplier, 
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
b) Be of proven reliability and performance, 
 
c) Have a standard video output, and 
 
d) Be compatible with camera control systems, video  signal management devices, monitors and video 
recorders. 
 
Preferably all the cameras should be supplied by on e manufacturer to allow for interchangeability if 
a camera fails. If necessary, colour cameras and mo nochrome cameras could be supplied by two 
different manufacturers. 
 
12.2.1.2 Colour cameras  
 
a) High-performance colour cameras suitable for ext ernal use should have a horizontal resolution of at  
least 460 lines. 
 
b) Standard performance colour cameras suitable for internal use should have a horizontal resolution of at least 330 
lines.  
 
12.2.1.3  Monochrome cameras  
 
a) High-performance monochrome cameras suitable for  external use should have a horizontal resolution of at least 
560 lines.  
 
b) Standard performance monochrome cameras suitable for internal use should have a horizontal resolution of at 
least 380 lines.  
 
12.2.1.4 Lenses  
 
a) All the lenses should be supplied by one manufac turer, be colour-corrected and have a neutral densi ty 
filter if required. 
 
b) Any variation in the effective f-number of zoom lenses should be declared when the focal length is 
changed from maximum to minimum. 
 
12.2.1.5  Camera and lens combination  
 
The camera and lens combination should 
 
a) Give the required fields of view when the focal length of the lens is selected in relation to the s ize of the camera 
image sensor,  
 
b) Have the correct resolution to reproduce the det ail to give the necessary information on the fields  of view,  
 
c) Be capable of operating within the range of expe cted light levels, and 
 
d) Have a lens image area equal to or greater than the area of the imaging device in the camera. 
 
12.2.1.6  Camera and lens housings  
 
The client should specify particular requirements t hat will influence the choice of the most appropria te 
camera and lens housings to be installed, such as, for example, the necessity for vandal-resistant hou sings  
or  the  fact  that  extreme  environmental  condit ions  exist  in  certain areas. This type of specif ication is 
particularly important in the case of external came ras and clients should be encouraged to clearly ide ntify 
additional requirements they deem important. Genera l requirements that apply to all housings, include the 
following: 
 
a) Access to the camera and lens for maintenance sh ould be simple and require the minimum use of tools  
while maintaining the security of the housing. 
 
b) The field of view should not be obstructed by th e housing. 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  c) The housing should not degrade the performance o f the video camera. 
 
d) The style and aesthetics of the housing should b lend in with the installation environment. 
 
e) All power, video and data cables that enter the housing should be protected by flexible conduit. 
 
f) There should be no exposed cable sheaths. 
 
g) The arrangement of the camera and lens mounting has to allow for the separation of the video- signa l 
earth from the housing and local safety earth.  
 
12.2.1.7  External camera and lens housings  
 
12.2.1.7.1  The following are additional requirements that app ly to externally mounted equipment: 
 
a) External camera and lens assemblies should be se curely mounted in a weatherproof enclosure. 
 
b) The housing should be of a rugged construction, resistant to corrosion and generally vandal-resista nt. 
 
c) The aperture window should be of toughened glass . 
 
d) The housing should be fitted with a sun visor. 
 
e) All cables and conduit should be secured to the housing by using suitably sized weatherproof glands . 
 
12.2.1.7.2  Optional requirements that could apply, depending on environmental conditions or location, are, 
for example 
 
a) The fitting of a self-parking wiper, and 
 
b) The fitting of a thermostatically controlled hea ter inside the housing. 
 
12.2.2  Pan-and-tilt units  
 
12.2.2.1  General  
 
The pan-and-tilt heads should be selected to suppor t the weight of the camera, lens, housing and any 
additional equipment and operate satisfactorily whe n subject to unbalanced platform loading and wind 
loading. In addition the following should also appl y: 
 
a) The use of extra-low voltage mechanisms is recom mended, from a safety point of view. 
  
b) The unit should be reliable and require minimum maintenance. 
 
c) The available pan angle of rotation should be no t less than 360 °. 
 
d) The tilt mechanism should enable a minimum varia tion of between 60 ° and 90 ° from the horizontal (or as 
specified elsewhere). 
 
e) The backlash on pan-and-tilt movement should be less than 0.5 °. 
 
f) Adjustable mechanical limit stops should be prov ided to restrict rotation where necessary. 
 
12.2.2.2 Fixed-speed unit  
 
Fixed-speed pan-and-tilt units should have 
 
a) A pan speed of not less than 6 ° per second, and 
 
b) A tilt speed of not less than 3 ° per second. 
 
12.2.2.3 Variable-speed unit  
 
Variable-speed pan-and-tilt units should have KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
a) A minimum range of pan speed of 0,5 ° per second to 24 ° per second, and 
 
b) A minimum range of tilt speed of 0,5 ° degrees per second to 15 ° per second. 
 
12.2.2.4 External applications  
 
External pan-and-tilt units should be of a rugged c onstruction designed for medium-duty operation. The  client should 
also note that planning permission might be require d for the installation of this type of equipment in certain 
locations.  
 
12.2.2.5 Brackets and towers  
 
Brackets and towers should 
 
a) Be designed to take into account the maximum supp orted load and the height at which equipment is required to 
operate,  
 
b) Be installed in accordance with the manufacturer 's instructions, 
 
c) Be installed such that access and maintenance (in cluding the replacement of cameras and pan-and- tilt heads) is 
not restricted, and  
 
d) Take into account the local environmental condit ions, including lightning protection. 
 
12.2.2.6 Towers  
 
Camera towers should 
 
a) Be rigid enough to minimize deflection of the ca mera during high winds; the movement should take in to account the 
height of the tower, the weight of the equipment an d the potential adverse effect on camera performance,  
 
b) Be protected against environmental degradation, and 
 
c) be telescopic or hinge down for access purposes,  where possible. 
 
12.2.2.7 Performance specification  
 
12.2.2.7.1  From the control point, the operator should, for ea ch and every camera (where relevant),be able to 
 
a) Operate the pan and tilt, 
 
b) Control the pan movement of the camera throughou t the complete range, 
 
c) Control the tilt movement of the camera througho ut the complete range, 
 
d) Control the operation of the zoom lens over the complete range, 
 
e) Operate the screen wash / wipe facility, 
 
f) Operate any auxiliary lighting associated with t he camera, 
 
g) Operate any other equipment or functions as spec ified, 
 
h) Select the order of the cameras and the time all owed for each camera view, and 
 
i) Set up a program to sequentially switch the requ ired number of cameras. 
 
12.2.2.7.2  Optional features of the camera controller that sh ould be specified separately include 
 
a) An autopan feature to allow for the automatic operat ion of PTZ cameras, 
 
b) Provision of continuous movement of the camera wi th adjustable pan speed, 
 
c) provision of random movement of cameras between various preset positions, program positions, dwell time at each KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  position and speed of movement between each positio n, and 
 
d) An alarm override feature. 
 
The speed of response of the pan, tilt and zoom fea tures should be within 0.1 s of the operator's actu ating 
the controls. 
 
12.2.2.8  Hardware specification  
 
12.2.2.8.1  The control equipment should 
 
a) Have standard video signal inputs and outputs, a nd 
 
b) Be compatible with cameras, monitors, video reco rders and video signalling management devices. 
 
12.2.2.8.2  The control panel should 
 
a) Have clear legible characters, 
 
b) Be robust, 
 
c) Be simple to operate, and 
 
d) Have joystick control when variable-speed pan-an d-tilt control is available; the movement of the jo ystick 
should be weighted to control the speed. 
 
12.2.3  Monitors  
 
12.2.3.1 General  
 
Monitors should 
 
a) Be metal-cased, unless otherwise specified, 
 
b) Have standard video signal inputs and outputs, 
 
c) Be compatible with cameras, control equipment an d video signal management devices, and 
 
d) Have switchable input impedance: 75 Ω / high impedance. 
 
The client should specify the optional features of the camera controller separately. 
 
12.2.3.2 Colour monitors  
 
For high-resolution colour CCTV systems the followi ng monitors should be used in conjunction with high -
resolution (460 line) colour CCD cameras: 
 
a) 14 inch or 15 inch colour monitors, which should  have a picture quality of greater than or equal to  450 
lines horizontal resolution; and 
 
b) 21 inch colour monitors, which should have a pic ture quality of greater than or equal to 400 lines 
horizontal resolution. 
 
Colour monitors should have accessible controls for  colour, contrast, brightness, horizontal hold and vertical hold.  
Medium resolution colour monitors should have a res olution of 250 lines to 350 lines, depending on the  size of the 
monitor.  
 
12.2.3.3 Monochrome monitors  
 
Monochrome monitors should have accessible controls  for contrast, brightness, horizontal hold and vertical hold. 
Standard monochrome monitors (sizes 5 inch to 20 inc h) should have a minimum resolution of 600 lines.  
 
12.2.4 Video signal management system  
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  12.2.4.1 General  
 
A CCTV video signal management system should 
 
a) Have the facility to display a video signal from  any camera on any monitor within a specified group , and 
 
b) Display the identification number of each monito r on the screen and on any recorded video signal. 
 
 
12.2.4.2 Video switchers  
 
Video switchers should 
 
a) Be used to manually or automatically switch a nu mber of video input signals to one or more outputs,  
 
b) Operate with no loss in picture quality or signa l strength, 
 
c) Have standard video signal inputs and outputs, 
 
d) Display descriptive text on real-time pictures a nd recorded pictures, 
 
e) Have sequential camera output, and 
 
f) Provide a manual option to select single camera o utput and to have adjustable camera dwell time during 
sequencing.  
 
12.2.4.3 Quad screen splitter  
12.2.4.3.1  Quad screen splitters should have the following sp ecification: 
 
a) Power supply: 240 V 50 Hz; 
b) Four standard video signal inputs; 
 
c) Two standard video signal outputs (monitor and V CR) and four loop-through video outputs; and 
 
d) Four alarm inputs. 
 
12.2.4.3.2  The quad splitter should have the following functi ons: 
 
a) Menu-driven set-up program; 
 
b) Full-screen display of selected picture; 
 
c) Automatic full-screen sequential switching; 
 
d) Real-time display; 
  
e) Alarm signal to enable relevant camera on full s creen and trigger VCR operation; 
 
f) At least a six-character description of each cam era picture; 
 
g) Freeze frame; and 
 
h) VCR facility. 
 
12.2.4.4 Multiplexers  
 
12.2.4.4.1  The following should be specified for a multiplexe r: 
 
a) Colour, or colour and monochrome, or monochrome cameras and monitors; 
 
b) Record only (simplex) or record and simultaneous  display (duplex); and 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
 
c) Number of inputs (cameras) (Multiplexer units ca n be designed for 4,8,9,10,16,24,32 or more cameras ; 
the installer should define the number of inputs in  the quotation.). 
12.2.4.4.2  Multiplexers should have the following functions: 
 
a) Power supply 240 V 50 Hz; 
 
b) loop-through inputs; 
 
 c) Number of outputs; 
 
d) Simultaneous recording of all inputs; 
 
e) Real-time display on time switcher output; 
 
 f) Record or real-time / multiscreen display on mo nitor; 
 
g) Alarm input to provide real-time record on alarm  cameras; 
 
h) Alarm input to trigger real-time recording of re levant camera; 
 
 i)alarm indication during recording and playback; 
 
 j) Text description available for each camera and recorded onto tape; 
 
 k) Date and time generation displayed on monitors and recorded pictures; 
 
 l) date and time synchronized between all multiple xers and VCRs; 
 
m) Sequential display of all cameras; 
 
n) Manual override to select single view; 
 
o) On-screen menu; 
 
p) Freeze frame on playback; and 
 
q) Time-lapse adjustment. 
 
All multiplexers should be from the same manufactur er to ensure full interchangeability. 
 
12.2.5 Picture storage/retrieval system  
 
12.2.5.1  Video recorders: minimum specification  
 
Video recorders should meet the following minimum s pecification: 
 
a) 625 lines CCIR European PAL colour system; 
 
b) Standard video signal inputs and outputs; 
 
c) Tape format: VHS 1-inch-wide high-density video tape; 
 
d) Maximum cassette size: 3 h (E180); 
 
e) Maximum rewind time (E180): 4,5 min; 
 
f) Tape speed: 23,39 mm/s (3 h mode); 
 
g) horizontal resolution: > 240 lines VHS colour; 
> 320 lines VHS monochrome; 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  h) Video signal-to-noise ratio > 45 dB; and 
 
i) Compatibility with cameras, monitors, and video signal management devices. 
 
12.2.5.2  Video recorder: standard functions  
 
12.2.5.2.1  The VCR should have the following standard functio ns: 
 
a) loop-through video; 
 
b) 3 h, 12 h or 24 h continuous-mode recording (48 h, 72 h, 168 h or 720 h are available if a weekend,  
week or month has to be covered); 
 
c) Alarm recording; 
 
d) Fully automatic head cleaning; 
 
e) end-of-tape alarm; 
 
f) noise-free still frame; 
 
g) Frame advance; 
 
h) Speed search / slow motion playback; and 
 
i) Tape recorded in standard 3 h mode can be replay ed on any VHS recorder. 
 
12.2.5.2.2  Video recorders should 
 
a) Be of the same manufacture and interchangeable, 
 
b) Be fully compatible with the multiplexers for op eration in time-lapse recording and playback modes,  
 
c) Be switchable between linear and step functions when used in playback mode, 
 
d) Have the facility to change the mode of the reco rders to either 3 h mode, 12 h mode or 24 h mode, 
 
e) Allow continuous time-lapse recording of all spe cified cameras, 
 
f) Allow real-time recording and playback to occur in 3 h mode, and 
 
g) Have a minimum start-up time or response from ti me-lapse mode to normal mode (if a time-lapse 
recorder is used).  
 
12.2.5.3  Video printers: common features  
 
Colour and monochrome video printers should have th e following common features: 
 
a) 625-line CCIR European PAL system; 
 
b) Standard video signal inputs and outputs; and 
 
c) Compatibility with cameras, monitors, recorders and video signal management devices. 
 
12.2.5.4  Colour video printers  
 
Colour video printers should provide the following:  
 
 a) Print size: minimum 150 x 100 mm; 
 
 b) Picture size: minimum 100 x 75 mm; 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
 
 
c) Picture resolution:        600 dots horizontal ( min. 100 mm) x 500 dots vertical (min. 75 mm); and 
 
 d) Print gradation : 256 levels process. 
 
Colour video printers should have the following fea tures: 
 
a) Instant response; 
 
b) High resolution; and 
 
c) Sequential printing. 
 
12.2.5.5  Monochrome video printers  
 
Monochrome video printers should provide the follow ing: 
 
a) Picture size:      minimum 90 x 68 mm; 
 
 b) Picture resolution:  minimum 800 (min. 90 mm) x  500 (min. 68 mm) dots; and 
 
c) Gradations:       256 grey levels (quasi). 
 
12.2.5.6  Infrared and laser transmission  
 
Infrared and laser transmission equipment shall 
 
a) Be firmly mounted to avoid movement and misalign ment, 
 
b) Comply with health and safety requirements, and 
 
c) Take into account the effects of poor weather co nditions and vegetation that can reduce signal stre ngth. 
 
12.2.5.7 Optical fibre  
 
Optical fibre transmission systems shall 
 
a) Utilize commonly available types of cable and ap propriate types of connector, and 
 
b) Be designed to accommodate at least three repair s in the cable during its lifetime. 
 
13 System test specification  
 
Before the CCTV system is handed over to the end us er, it should be thoroughly checked electrically, 
mechanically and visually to ensure that it complie s with the technical specification. This checking o f the 
system should comprise the following: 
 
a) All parts of the CCTV system should be checked v isually and functionally. The basis for the functio nal 
check should be the system test specification as de veloped from the operational requirement and the 
technical specification. 
 
b) The visual test should cover the quality of work manship of the installation, the functional quality  of the 
equipment and their compliance with the technical s pecification. 
 
c) The functional test should include checking the functional compatibility of the components of the s ystem. 
 
In large systems it is recommended that inspections  be carried out at regular intervals during the 
installation of the system. Practical testing and c ommissioning should be carried out by CCTV personne l 
other than those employed on the installation of th e equipment or system (or both). Commissioning 
personnel should carry out the tests detailed in th e acceptance test procedures.  
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  14 System maintenance requirements  
 
The CCTV system should be maintained periodically i n accordance with the equipment manufacturers’ 
recommendations and any specific requirements of th e client. It is recommended that the CCTV 
contractor provide a maintenance plan that details the tests to be undertaken, a recommended list and 
quantities of spares to be held, the service period s, and special test instruments and tools required.  
This information will form part of any maintenance agreement to be concluded between the end user 
and the contractor.  
 
It is further recommended that an identification pr ocedure be established for the CCTV contractor's 
maintenance personnel, and that the end user's repr esentative be notified before the start of a 
maintenance inspection. It might also be necessary for parts of the CCTV system to be inspected 
outside normal working hours; this should be clearl y stated in the maintenance agreement. 
 
Should a problem occur outside the normal maintenan ce inspection visit, it is essential that the end 
user be kept informed of the contractor’s emergency  service facilities, such as names, addresses and 
telephone numbers (or contact details) of service p ersonnel. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  
             Annex A  
  (Informative) 
 
                Layout schematic of a typical large  CCTV surveillance system  
 
The basic items required for any simple CCTV system  are a camera, a lens, a transmission link, and a m onitor. 
As the system becomes more comprehensive, additiona l items are provided, such as video switchers or 
multiplexers, recorders, hard-copy printers and oth er ancillary equipment (for example, pan-and-tilt m echanisms, 
housings, text generators, etc.). The following dia gram illustrates a typical large CCTV system that u ses some of 
these items of equipment. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure A.1 – Typical large CCTV system  
 
 
 
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  
 
 
 Annex B  
                                                                      (Informative) 
Typical CCTV system that uses a matrix switcher  
 
Matrix switchers are based on microprocessor princi ples that allow a tremendous potential of flexibili ty 
in routing and processing signals. The pre-programm ing and automating of camera pan or tilt (or both),  preset 
camera pointing and automatic switching functions a re combined in one control unit. These  switchers range from 
small compact units that control 16 or 32 cameras, several monitors and keyboards to large modular 
systems that control, say, 1 028 cameras and 99 mon itors. The following  diagram shows a typical CCTV 
system and equipment layout that uses a matrix swit ching unit. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
         Figure B.1 – CCTV system that uses a matrix switchi ng unit  
 
 
 
 
 
 KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009   
Annex C  
(Informative) 
 
Index of protection ratings  
 
 
The protection is defined by two digits prefixed by  the letters IP, or index of protection. The first digit 
indicates the degree of protection that is provided  with respect to the equipment inside the enclosure , 
and the second digit indicates the protection that is provided with respect to the harmful ingress of 
water. In some countries a third digit is sometimes  added (although not too common), which indicates 
the degree of mechanical protection. The following table lists the various degrees of protection in te rms 
of the two-digit system only. 
 
 
 IP RATINGS 
1ST IP Degree of 
protection\digit Definition 1ST IP Degree of 
protection\digit Definition 
0 Zero protection No special protection 0 Zero prot ection No special protection 
 
1 Protection against solids 
greater than 50 mm 
 
 
2 Protection against solids 
greater than 12 mm 
 
 
 
 
 
3 Protection against solids 
greater than 2.5 mm 
 
 
 
4 Protection against solids 
greater than 1.0 mm 
 
 
5 Dust- protected 
 
 
 
 
 
6 Dust- tight 
  
Large surface of human body such as 
hand, none against deliberate access 
 
Fingers or similar objects no 
exceeding 80mm in length 
 
 
 
 
 
 
Tools/wires of thickness or diameter 
greater than 1.0 mm 
 
 
 
Wires or strips greater than 1.0 mm 
 
 
 
Total protection against dust is not 
provided but sufficient protection to 
allow satisfactory operation 
 
 
 
No ingress of dust  
1 Protection against 
dripping water 
 
 
2 Protection against 
dripping when tilted up to 
15 0 
 
 
 
 
3 Protection against water 
spray 
 
 
 
4 Protection against 
splashing water  
 
 
5 Protection against 
splashing water 
 
 
 
 
6 Protection against 
heavy seas 
 
 
 
 
7 Protection against the 
effects of submersion 
 
 
 
 
 
8 Protection against the 
effect of continuous 
submersion 
 
 
 
 
 
 
  
Vertically falling dripping 
water should have no harmful 
effect 
 
Vertically falling dripping 
water shall have no harmful 
effect when the enclosure is 
tilted at any angle up to 15 0 
from its normal position 
 
 
Water falling as a spray at an 
angle of up to 60 0 from the 
vertical shall have no harmful 
effect. 
 
Water splashed against the 
enclosure from any angle 
shall have no harmful effect.  
 
Water projected by a nozzle 
against the enclosure from 
any angle shall have no 
harmful effect. 
 
 
Water from heavy seas  or 
water projected by powerful 
jets shall not enter the 
enclosure in harmful 
quantities 
 
Ingress of water in a harmful 
quantity shall not be possible 
when the enclosure is 
immersed in water under 
defined conditions of time 
and pressure 
 
Suitable for continuous 
submersion in water under 
conditions specified by the 
manufacturer. KENYA STANDARD                                                              KS 2110-3:2009 
© KEBS 2009- All rights reserved                                                         First Edition,  2009  
 
 
 
 
          Annex D 
                                                                     (Informative) 
 
Typical video transmission methods  
 
In its most common form, the CCTV video signal is t ransmitted at baseband frequencies over a coaxial 
cable. However, it is often a requirement that vide o signals be transmitted from a camera site to a 
remote location. The following diagram illustrates the various video transmission methods available. 
The actual choice of transmission medium will be di ctated by circumstances associated with the 
camera and control point location. Often there will  be more than one option of transmission method and  
it will often come down to a trade off between qual ity and security of the video signal and the cost 
involved. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure D.1 – Typical video transmission methods