EDC3 ( 5237 ) P3  
            
           
   
 
 
 
 
 
DRAFT TANZANIA STANDARD  
(Draft for comments only)  
 
Mini-Grid System –  
 
Part 6:  Aerial Bundled Cable s (ABC) (0.6/1kV )  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF STANDARDS  
 
 
TBS 2017                                                                                   First Edition 2017  
 
 
 
  
 
Table of contents  
0. Forward  ................................ ................................ ................................ ................................ ....................  3 
1. Scope: ................................ ................................ ................................ ................................ .........................  4 
2. References  ................................ ................................ ................................ ................................ ...............  4 
3. Quality Control  ................................ ................................ ................................ ................................ ....... 4 
4. Service Conditions  ................................ ................................ ................................ ................................  4 
5. Electrical System Parameters  ................................ ................................ ................................ ...........  5 
6. Design  ................................ ................................ ................................ ................................ ........................  5 
7. Phase Conductors ................................ ................................ ................................ ................................ .. 5 
8. Neutral /Messenger Conductor  ................................ ................................ ................................ ........  6 
9. Street Light Conductor  ................................ ................................ ................................ ........................  6 
10. Bundling of Cores  ................................ ................................ ................................ .............................  6 
11. Lay Pitch of Bundle  ................................ ................................ ................................ ..........................  7 
12. Dimensional Requirements for All -Aluminum Conductors  ................................ ..............  7 
13. Dimensional Requirements for Aluminum Alloy Neutral C onductors  .........................  8 
14. Joints  ................................ ................................ ................................ ................................ .....................  9 
15. Requirements for XLPE Insulation  ................................ ................................ ............................  9 
16. Tests  ................................ ................................ ................................ ................................ ....................  10 
17. Type Test  ................................ ................................ ................................ ................................ ...........  10 
18. Sample Tests  ................................ ................................ ................................ ................................ .... 11 
19. Routine Tests  ................................ ................................ ................................ ................................ ... 11 
20. Test Reports  ................................ ................................ ................................ ................................ ..... 11 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
  
 
0. Foreword 
 
This Draft Tanzania Standard is part of an integrated set of specifications and standards issued to 
govern design and construction of mini -grid power systems in Tanzania.  The mini -grid standards, have 
been developed to support improved residential, commercial and public services for rural commu nities 
of Tanzania. The mini -grid energy systems, when properly designed, will support affordable and reliable 
energy supply for remote households, community services, commercial and economic activities 
including shops, workshops, micro -industry, fresh wat er pumping, secondary schools, health services, 
public  lighting, places of worship or cultural activities, agro -processing activities and other activities  
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1. Scope:  
 
1.1 This standard covers minimum technical requirements for the design , manufacture, test ing 
and supply of  two, three, and four core twisted unsheathed cable rated 0.6/ 1 kV (Um=1.2kV)  for use 
on 230/400V, 50 Hertz, three phase four wire multiple neutral grounded  overhead line single phase 
and three phase powe r distribution networks  of mini-grid system s.  
1.2 The rated voltage of the cable is 0.6/1.0 kV, whereas 600 volts is the rated power frequency 
voltage between conductor and earth for which the cable is designed and 1000 volts is the rated 
power frequency volt age between conductors, for which the cable is designed. This cable is 
hereinafter referred to as Aerial Bundled Cable or ABC.  
 
Note 1 This standard shall be read in conjunction with other relevant – Tanzania Standards,  
applicable standards and specifications to have uniformity, compatibility and standardization in 
the distribution system.  
2. Normative References  
The ABC cables shall conform to the latest editions of the IEC standards applicable to their 
construction, incl uding but not limited to those listed below, and to their normative references:  
 
IEC 60104 Aluminium -magnesium -silicon alloy wire for overhead line conductors  
IEC 61089 Round wire concentric lay overhead electrical stranded conductors  
IEC 60228 Conductors of Insulated Cables  
IEC 60502 -1 Cables  for Rated  Voltages  of 1kV (Um=1.2kV) and 3kV (Um=3.6kV) 
TANESCO Specification S01 Supply and Installation of Plant and Equipment  
TANESCO engineering manuals.  
 
In the event of conflict between these standards and this standard , this s tandard  shall govern . 
3. Quality Control  
Aerial Bundled Cable shall be manufactured in a plant that has  established a credible past record of 
production of  cables of similar ratings, design s, and characteristics and that holds ISO: 9001  
certif ication for quality management.  
4. Service Conditions  
Aerial bundled cable (ABC) shall be suitable for outdoor operation under the local service conditions 
in Tanzania, which are as follows:  
 
a) Altitude above mean sea level (MSL): <3,000 metres  
 
b) Maximum/record yearly high ambient temperature: + 40°C 
 
c) High humidity promoting the growth of fungi  
 
d) Extended periods of intense sun exposure  
 
In accordance with the IEC standards, altitudes not exceeding 1000 m are considered as normal 
service conditions.  Altitudes high er than 1000 m are considered as abnormal service conditions, 
which may require special considerations in the design, manufacture or application of the materials or 
equipment .  It is the responsibility of the proponent to recognize the particular conditions on any site 
and call them to the attention of the manufacturer.  
  
 5. Electrical System Parameters  
Mini-grids may be single or three -phase but regardless, s ystem parameters of mini-grids for the low 
voltage overhead line power distribution network are as follows:  
 
a) Nominal system low voltage (U): 230/400V (±10%)  
 
b) Maximum permissible system low voltage (U m):  253/440V  
  
c) Minimum permissible system low voltage :  215/374V  
 
d) System frequency: 50 Hz  
 
e) Neutral grounding arrangement: multi - grounded  
 
f) Power frequency withstand voltage for 5 minutes: 3kV p 
6. Design  
 
6.1     The cable shall be designed for a maximum permissible continuous conductor temperature of 
90°C, emergency loading conductor temperature of 105°C and maximum conductor short circuit 
withstand temperature of 250°C for 5 seconds.  
6.2 The insulated conductors and insulated neutral of the ABC shall form a bundle, which shall 
comprise one or more single core insulated alumi num phase conductor(s) and a street light conductor 
if so specified, all twisted together with an insulated aluminum alloy conductor to be used as neutral 
and messenger.   
6.3 The total horizontal tension of the conductor shall be carried by the aluminum al loy 
neutral/messenger wire.  
 
7. Phase Conductors  
7.1 The phase conductors shall be constructed of round hard drawn electrical grade aluminum wires 
(61% conductivity per IACS), circular stranded into conductors of diameter and resistance complying 
with the req uirements of this standard  
7.2 The outer layer shall have a right -hand direction of lay. The surface of the conductor shall be 
smooth.  
7.3 The insulation shall be XLPE insulation filled with 2.5% carbon black or other certified or approved 
suitable UV prot ector extruded over the conductors.  
7.4 The XLPE insulation shall comply with the requirements of IEC 60502 -1 and this specification, 
and shall be suitable for continuous operation at a conductor temperature of +90°C.  
7.5 The insulation on phase conductors shall be embossed with a raised rib 1mm high on the entire  
length of each phase conductor as follows:  
 
i) One rib on phase 1   
ii) Two ribs on phase 2   
iii) Three ribs on phase 3   
 8. Neutral /Messenger Conductor  
8.1 The neutral conductor shall be constructed of round hard drawn  aluminum -magnesium -silicon alloy 
wire conforming to the requirements of Type B of IEC 60104 , circular stranded into conductors of 
diameter and resistance complying with the requirements of this  standard.  
8.2 Direction of lay shall be right handed.  
8.3 The neutral conductor shall be insulated with XLPE insulation filled with 2.5% carbon black or other 
certified or approved suitable UV protectant.  
8.4 The XLPE insulation shall comply with the requirements of IEC 60502 -1 and this specification and 
shall be suitable for continuous operation at a conductor temperature of +90°C .  
8.5  The insulation of the neutral conductor shall be embossed with eight raised ribs 1mm high on the 
entire length of e ach neutral conductor.   
 
8.6  The neutral conductor shall be embossed (matrix print shall not be acceptable) at a regular 
interval of two metres with the  following  information : 
 
a) The m anufacturer’s name   
b) Voltage designation  
c) Type of insulation   
d) Size of t he neutral and phase conductors   
e) Progressive cumulative length measurement  with the highest length mark on the outer 
end of the cable  
f) Year of manufacture  
9. Street Light Conductor  
9.1 When a street light conductor is specified, it shall be supplied as an additional core bundled with 
the ABC, consisting of 16mm2 all aluminum stranded conductor covered with XLPE insulation.  
9.2 The XLPE insulation of the street light conductor shall be embossed with word 'SL' at regular 
intervals of two metres on its entire length.  
9.3 The properties of conductor and XLPE shall be equal to those of the phase conductor specified 
in this standard . 
10. Bundling of Cores   
 
The cores shall be bundled into cables by using two or thr ee cores for single phase,  
four cores for three phase  and five cores for three phas e with street light facilities.  
The different combinations of bundles are  as indicated : 
 
10.1 For  Three Phase Four Wire System s  
 (No. of aluminum  (Al) phase conductors) x (Al conductor cross section mm2) + (No. of aluminum 
alloy conductors) x (AI alloy conducto r cross section mm2) + (No . of aluminum street light 
conductors) x (Al street light conductor cross section mm2) 
a) Without street light conductor :   
• 3×25  + 1x25    
• 3×50 + 1×50    
• 3x70 + 1x70 
• 3×100  + 1×100    
 b) With street light conductor : 
• 3x50 + 1x50 + 1x16  
• 3x70 + 1x70+1x16  
• 3×100  + 1×100  + 1x16 
10.2 For Single Phase Systems   
 (No. of aluminum phase conductors) × (Al conductor cross section mm2) + (No. of aluminum alloy 
conductors) × (Al Alloy conduc tor cross section mm2) 
• 1x16  + 1x16  
• 1×25  + 1×25  
• 2x 25 +1x25  
• 2×50 + 1×50    
11.  Lay Pitch of Bundle  
The cores of a bundle shall be twisted with a right hand lay, so that the cores conform to the direction 
of the central part of the letter Z, when the cable is held vertically. The pitch of the bundling specified 
in Table -1. 
 
 
Table -I 
Lay pitch of the bundled cores  
Cross -section of phase 
conductor (mm2)  Assembly pitch (cm)  
10 30-50 
16 40-70 
25 50-80 
40 60-90 
63 70-100 
100 80-110 
 
12.  Dimensional Requirements for  All-Aluminum Conductors  
The dimensions, construction and properties of insulated  all aluminum  conductors are given in 
Table -Il. 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 TABLE -II 
Stranded Phase Conductor (Aluminum ) 
 
Nominal 
Cross 
Section of 
Conductor  
 No. Of 
Strands 
Nominal 
dia. of  
each  
 Nominal 
diameter 
of 
Conductor  
 Maximum 
DC 
Resistance 
at 20°C*  Rated 
Strength  Nominal  
Thickness  
of XLPE  
Insulating 
sheath*  Minimum 
Thickness 
of XLPE 
insulating 
sheath **  
(mm2) Strand 
(mm)  (mm)  (Ohms/km)  (kN) (mm)  (mm)  
 
16 
 
25 
 
50 
 
70 
 
100  
7/1.71  
 
7/2.21 
 
7/3.1 
 
7/3.66 
 
7/4.39   
5.1 
 
6.6 
 
9.3 
 
11.0 
 
13.2  
1.80 
 
1.07 
 
0.542 
 
0.389 
 
0.27  
2.8 
 
4.6 
 
8.3 
 
11.3 
 
16.00  
1.1 
 
1.2 
 
1.5 
 
1.5 
 
1.5  
1.0 
 
1.1 
 
1.4 
 
1.4 
 
1.4 
 
* Note that these values exceed the requirements of IEC 60502 -1 
** Minimum requirement at any point of cable circumference -this is a governing requirement and exceeds the 
requirements of IEC 60502 -1 
 
13. Dimensional Requirements for Aluminum Alloy Neutral Conductors  
The dimensions, constructions and properties of aluminum alloy conductors stand ardized for use 
are given in Table -III.  
 
Table -III 
 
Nominal 
cross 
section  Actual 
conductor 
cross 
section  No. of strands / 
Nominal dia. of 
each strand  Overall  
diameter  
of 
conductor  Maximum  
DC 
resistance  
at 20 ˚C 
 Minimum  
breaking  
strength  Nominal  
thickness  
of XLPE  
insulation * Minimum 
thickness 
of XLPE 
insulation
** 
(mm) ² 
 (mm) ² (mm)  (mm)  (Ohm/km ) (kN) (mm)   
        
16 18.8 7/1.8 5 5.49  1.75 5.43 1.1 1.0 
25 30.1  7/2.3 4 7.02  1.094 8.44 1.2 1.1 
50 59.9 7/3.3 9.9 0.5498  16.8 1.5 1.4 
70 84.0  7/3.91  11.7 0.3917  23.56 1.5 1.4 
100 118.9 7/4.65  13.95  0.2769 33.3 1.5 1.4 
 
* Note that these values exceed the requirements of IEC 60502 -1 
** Minimum requirement at any point of cable circumference -this is a governing requirement and exceeds the 
requirements of IEC 60502 -1  
 14. Joints  
 
a) There shall be no joints in any wire of stranded conductor containing seven wires, except those 
made in the base r od or wire before final drawing . 
 
b) In stranded conductor containing more than seven wires, joints in individual wires are permitted, 
in addition to those made in the base rod or wires before final drawing, but no two such joints 
shall be less than 15m apart in the complete stranded conductor. Such joints shall be made by 
resistance butt welding, fuse welding or cold pressure welding. Joints made by resistance butt 
welding shall, subsequent to welding, be annealed over a distance of at least 250mm on each 
side of the joint.   
15. Requirements for XLPE Insulation  
15.1 General  
 
The insulation of all insulated conductors shall consist of cross linked polyethylene filled with 2.5% 
carbon black  or other equally effective UV protectant,  suitable for use in outdoor wet and dry locations 
at a continuous conduc tor operating temperature of 90oC throughout its life and for service under the 
conditions described  in this standard . The XLPE insulation shall comply with the requirements of IEC 
60502 -1. 
15.2 Physical Requirements  
15.2.1 Original Physical Properties  
 
a) Tensile strength, min. kg/cm2:127 
b) Elongation at rupture minimum percent (%) :200 
15.2.2 Physical Properties after Accelerated Aging  
After air oven exposure at 135 ± 3oC for 168 hours:  
 
a) Tensile strength minimum  percent ( %) of un-aged value: 75  
b) Maximum percent (%) of un-aged value: 125 
c) Elongation, min imum  percent (%) of un -aged value: 75 
d) Elongation maximum percent (%) of  un-aged value: 125 
15.2.3 Water Absorption  
 
When tested by the gravimetric method the insulation shall show a maximum increase in 
mass of 1 mg/cm2 following immersion in water at 850C, ±20C for 336 hours.     
15.2.4 Insulation Resistance  
 
When tested in accordance with IEC 60502 -1 clause 17, insulation resistance at maximum 
conductor temperature of 900C shall not be less than 1012 ohm-cm and the insulation resistance 
constant K i shall not be less than 3.67.  
 15.2.5 Hot Set Test ( in accordance with the lEC 60811  standard )  
 
• Temperature: 2000C 
• Duration: 15 Minutes  
• Mechanical stress: 20 N/cm2 
• Elongation under load: 175% Max imum  
• Permanent elongation: 15% Max imum  
14.2.6   Shrinkage Test ( in accordance with the lEC-60811 -1-3 standard ) 
  
 • Distance - between mark: 200 mm 
• Temperature:  130 ± 3 0C 
• Shrinkage test: 4% Max imum  
• Duration: 1 hour  
14.3.    UV Resistance  Test 
 
Retention of 80% of tensile and elongation properties following exposure of samples of XLPE 
insulation to  either a carbon arc or a Zenon arc lamp in accordance with ISO 4892 -3 for a period 
of 720 hours.   
16. Tests  
a) Cables shall be tested as specified in this section.  Except as noted, testing procedure and 
pass/fail requirements shall be as specified in IEC 60502 -1 for XLPE insulated cables.   
b) Type tests shall be carried out in an accredited independent testing laboratory on cables and 
materials of equivalent design and material characteristics to those proposed for delivery 
under this order.   
c) Sample and rou tine tests shall be carried out in the manufacturer’s laboratory.  
17.    Type Tes t 
Both electrical and non -electrical type tests sh all have been completed on ABC c ables of similar 
design  in accordance with IEC referenced standards and  evidence of successful completion of such 
tests sha ll be provided with the tender.  
17.1 Electrical Type Tests  
 
ABC cables shall have successfully passed the electrical type tests in accordance with the 
reference IEC standar d for the following parameters:  
 
a) Insulation resistance test at ambient temperature  
 
b) Insulation resistance measurement at maximum conductor temperature in normal 
operation  
 
c) Voltage test for four hours  
17.2   Non-Electrical Type Tests  
 
ABC cables shall have successfully passed the non -electrical type tests in accordance with the 
reference IEC standard for the following parameters:  
 
a) Dimension test  - measurement of thickness and uniformity  
The results of the dimension tests shall meet the minimum insulation t hickness 
requirements of Tables II and III of this standard , which exceed the requirements of 
IEC 60502 -1. 
b) Mechanical properties -tensile strength and elongation at break . 
i) Without Ageing  
ii) After ageing in an air oven  
iii) After ageing of pieces of complete cabl e 
 
c) Hot set test  
d) Water absorption   
 e) Shrinkage test  
f) Sunlight Resistance test on the XLPE insulation consisting of exposure to either a 
carbon arc or a Xenon arc lamp in accordance with ISO 4892 -3 for a period of 720 
hours while retaining 80% of the sample’s tensile and elongation properties  
18. Sample Tests  
18.1 Sample tests shall be carried out during production of cables in accordance with IEC 60502 -1 for 
XLPE insulated cables.  
18.2  The number of samples taken for physical tests shall be as determined by the ISO 9001 
procedure in place at the  manufacturer, but not less than the number of samples required by application 
of Table 12 of IEC 60502 -1 for multicore cables, that is 1 sample for every 10km of cable produced 
under the purchase ord er.  Sample tests shall include as follows : 
 
a) Conductor examination for compliance with the requirements of this standard . 
 
b) Check of insulation thickness  in accordance with IEC 60502 -1, except that the minimum 
allowable insulation thickness shall comply with the requirements of Tables II and III of this 
standard.  
 
c) Hot set test in accordance with IEC 60502 -1 
19.   Routine Tests  
19.1 Routine tests shall be carri ed out on every manufactured leng th of cable without exception. No 
reduction in the number of lengths to be tested is allowable, regardless of any quality control procedure 
that may have been instituted by the manufacturer.    
19.2 Routine test s shall be carried out in accordance with IEC 60502 -1 and shall include:  
 
a) Measurement of electrical resistance of conductors  except that the values of conductor 
resistance shall be those in Tables II and III of this standard . 
  
b) AC v oltage test for multicore cables without individually screened cores.  
 
20.   Test Reports  
20.1 Certified type test reports shall be provided for all specified tests  in accordance with IEC 60502 -
1. Type test reports or certificates of qualification  shall be provided at the time of tender from  Tanzania 
Bureau of Standards or  an independent accredited testing laboratory.    
20.2 Certified test reports for sample tests and for routine tests shall be submitted upon completion of 
production and prior to release for shipment.