KINGDOM OF SAUDI ARABIA 
SAUDI STANDARDS AND QUALITY ORGANIZATION 
 
 
SASO 
 
 
SAUDI STANDARD 
DRAFT No.  20127:2010 
 
  
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –  
 
Part 7-3: Ancill ary equipment –  
Safety requirements for fuse terminal blocks 
 
 
 
 
  
 
SAUDI STANDARDS AND QUALITY ORGANIZATION 
THIS DOCUMENT IS A DRAFT SAUDI STAN DARD CIRCULATED FOR COMMENT. IT IS, 
THEREFORE SUBJECT TO CHANGE AND MAY BE REFERRED TO AS A SAUDI STANDARD UNTIL 
APPROVED BY THE BOARD OF DIRECTORS. 
 
 SAUDI ARABIAN STANDARD  SASO ……/2010 
 2 
 
   CONTENTS 
 
INTRODUCTION ............................................................................. ﺧﻄﺄ! ﻣﻌﺮّﻓﺔ  ﻏﻴﺮ اﻟﻤﺮﺟﻌﻴﺔ  اﻹﺷﺎرة.  
 
1 General ..................................................................................................................... ..... 4 
1.1 Scope.................................................................................................................... 4 
1.2 Normative references ............................................................................................ 5 
2 Definitions ................................................................................................................. ..... 5 
3 Classification .............................................................................................................. .... 6 
4 Characte ristics ............................................................................................................. .. 6 
4.1 Fuse-links ............................................................................................................. 6 
4.2 Rated power dissipation value ............................................................................... 7 
4.3 Rated and limiting values ....................................................................................... 7 
5 Product in formation ........................................................................................................ 7 
5.1 Marking ................................................................................................................. 7 
5.2 Additional information ............................................................................................ 8 
5.3 Marking on the packing unit ................................................................................... 8 
6 Normal service, mounting and transport conditions .......................................................... 8 
7 Constructional and performance requirements ................................................................. 9 
7.1 Constructional requirements .................................................................................. 9 
7.2 Performance requirements ................................................................................... 10 7.3 Electromagnetic compatibility (EMC) .................................................................... 11 
8 Tests 11 
8.1 Kinds of test ........................................................................................................ 11 
8.2 General ............................................................................................................... 11 8.3 Verification of mechan ical characteristics ............................................................. 11 
8.4 Verification of electr ical characteristics ................................................................ 14 
8.5 Verification of ther mal characteristics ................................................................... 18 
8.6 Verification of EM C characteristics ....................................................................... 25 
 
Annex A (normative )  Gauges ............................................................................................. 25 
Annex B (informative)  Power dissipation values P
V and PVK ................................................ 26 
Annex C (normative)  Order of test s and number of specimens ............................................ 35 
 Bibliography .................................................................................................................. ..... 36 
 
 
      SAUDI ARABIAN STANDARD  SASO ……/2010 
 3 
 
    
INTRODUCTION  
The Saudi Standards and Quality Organiza tion (SASO) has adopted the International 
Standard IEC 60947-7-3/2002 “LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR 
– Part 7-3: Ancillary equipment –  Safety requirements for fuse terminal blocks ” issued by the 
International Electrotechnical Commission (IEC). It has been adopted without any technical modifications with a view to  its approval as a Saudi standard. SAUDI ARABIAN STANDARD  SASO ……/2010 
 4 LOW-VOLTAGE SWITCHGE AR AND CONTROLGEAR –  
 
Part 7-3: Ancill ary equipment –  
Safety requirements for fuse terminal blocks 
   
1 General 
1.1 Scope 
This part of IEC 60947 applies to fuse terminal blocks with screw-type or screwless-type 
clamping units for the connection of rigid (solid or stranded) or flexible copper conductors for 
the reception of cartridge fuse-links in accordance with IEC 60127-2, intended primarily for 
industrial or similar use in circuits not exceeding 1 000 V a.c., up to 1 000 Hz or 1 500 V d.c., and having a maximum short-circuit breaking capacity of 1 500 A. 
They are intended for installation in electrical equipment with enclosures which surround the 
fuse terminal blocks to such an extent that they are accessible only with the aid of a tool. 
For certain applications, for example in control circuits, the fuse terminal blocks may be 
designed exclusively for short-circuit protection. 
NOTE This standard may be used as a guide for fuse termin al blocks for the reception of special cartridge fuse-
links which do not meet the requirements of IEC 60127-2. 
The object of this standard is to specify safety requirements and test methods for the 
mechanical, electrical and thermal characteristics of fuse terminal blocks, to ensure the 
compatibility between te rminal blocks and sta ndardized fuse-links. 
This standard may be used as a guide for 
− fuse terminal blocks r equiring the fixing of special devices to the conductors, for example 
quick connect terminations or wrapped connections, etc.; 
− fuse terminal blocks providing direct contact to the conductors by means of edges or 
points penetrating the insulation, for example insulation displacement connections, etc. 
Where applicable in this standard, the term “clamping unit” has been used instead of the term 
“terminal”. This is taken into account in case of reference to IEC 60947-1. SAUDI ARABIAN STANDARD  SASO ……/2010 
 51.2 Normative references 
The following referenced documents are indispensable for the application of this document. 
For dated references, only the edition cited applies. For undated references, the latest edition 
of the referenced document (including any amendments) applies. 
IEC 60127-1:1988, Miniature fuses – Part 1: Definitions for miniature fuses and general 
requirements for miniature fuse-links  
Amendment 1 (1999) 
IEC 60127-2:1989, Miniature fuses – Part 2: Cartridge fuse-links  
IEC 60216-1:2001, Guide for the determination of thermal endurance properties of electrical 
insulating materials – Part 1: General guidelines for ageing procedures and evaluation of test 
results  
IEC 60695-2-2:1991, Fire hazard testing – Part 2: Test me thods – Section 2: Needle-flame test 
Amendment 1 (1994) 
IEC 60947-1:1999, Low-voltage switchgear and controlgear – Part 1: General rules  
Amendment 1 (2000)  
Amendment 2 (2001) 
IEC 60947-7-1:2002, Low-voltage swit chgear and controlgear – Part 7-1: Ancillary equipment – 
Terminal blocks for copper conductors  
ISO 3:1973, Preferred numbers – Series of preferred numbers 
ISO 4046:1978 , Paper, board, pulp and related terms – Vocabulary 
2 Definitions 
For the purpose of this part of IEC 60947, definitions given in IEC 60947-7-1, together with 
the following definitions, apply. 
2.1 
fuse terminal block terminal block base with a fuse-carrier 
2.2 
terminal block base insulating part of a fuse terminal block carryi ng the clamping units and contacts, intended to 
be fixed to a support 
2.3 
fuse-carrier movable part of a fuse terminal block designed to carry the cartridge fuse-link and enable 
its exchange 
NOTE The fuse-carrier can be mechanically coupled with the terminal block base. SAUDI ARABIAN STANDARD  SASO ……/2010 
 62.4 
maximum power dissipation of the cartridge fuse-link 
2.4.1  in the case of an overload of PV1, equal to the maximum sustained power dissipation as 
given in IEC 60127-2 
2.4.2  in the case of a nominal load of PV2, equal to the power dissipation value calculated 
from the nominal values, i.e. the maximum voltage drop and the rated current in accordance 
with IEC 60127-2 
2.5 
separate arrangement of a fuse terminal block 
arrangement of a single fuse terminal block between adjacent terminal blocks (without 
additional function) (see figure 2) 
NOTE Mounting of fuse terminal blocks side by side wi th a spacing that securely prevents any mutual thermal 
influence is also considered as a separate arrangement. 
2.6 
compound arrangement of fuse terminal blocks arrangement of two or several fuse terminal blocks side by side or the arrangement of a single fuse terminal block between adjacent terminal bl ocks with additional function (see figure 3) 
NOTE Additional functions within the meaning of th is standard include all components which may thermally 
influence the function of the fuse terminal block due to their own power dissipation. 
2.7 
rated power dissipation value of a fuse terminal block 
maximum permissible value with which the fuse terminal block can be continuously loaded by 
the cartridge fuse-link under specified conditions 
2.8 
rated cross-section value, stated by the manufacturer, of a rigid (solid or stranded) or flexible conductor to which 
certain thermal, mechanical and electrical requirements are referred 
2.9 
rated connecting capacity range of cross-sections and/or the number of conductor cross-sections for which the fuse terminal block is designed 
3 Classification 
Fuse terminal blocks are classified as follows: 
a) fuse terminal block with separate fuse-carrier, e.g. screw type or plug-in type; 
b) fuse terminal block with mechanically  coupled fuse-carrier, e.g. hinged type. 
4 Characteristics 
4.1 Fuse-links 
The fuse links shall be in accordance with IEC 60127-2. SAUDI ARABIAN STANDARD  SASO ……/2010 
 74.2 Rated power dissipation value 
4.2.1 Overload and short-circuit protection ( PV) 
The rated value ( PV) is the maximum permissible power dissipation value of a fuse terminal 
block under overload and short-circuit conditions related to an ambient temperature of 23 °C. 
4.2.2 Exclusive short-circuit protection ( PVK) 
The rated value ( PVK) is the maximum permissible power dissipation value of a fuse terminal 
block, which can accept a fuse-link with an equal or lower sustained power dissipation used 
under exclusive short-circuit conditions and related to an ambient temperature of 23 °C (see annex B). 
4.3 Rated and limiting values 
4.3.1 Rated voltages 
Subclause 4.3.1 of IEC 60947-7-1 applies. 
4.3.2 Void 
4.3.3 Standard cross-sections 
Subclause 4.3.3 of IEC 60947-7-1 applies. 
4.3.4 Rated cross-section 
Subclause 4.3.4 of IEC 60947-7-1 applies. 
4.3.5 Rated connecting capacity 
Subclause 4.3.5 of IEC 60947-7-1 applies with the following addition. 
The conductor cross-section specified for the temperature-rise test according to 8.4.5 shall be 
included in the range of the rated connecting capacity. 
4.3.6 Working voltage 
See 2.5.52 of IEC 60947-1. 
5 Product information 
5.1 Marking A fuse terminal block shall be marked in a durable and legible manner with the following: 
a) the name of the manufacturer or a trade mark, by which the manufacturer can be readily 
identified; 
b) a type reference permitting its identification in order to obtain relevant information from the 
manufacturer or his catalogue; 
c) energy flow direction, if required to ensure protection against electric shock, according 
to 7.1.8, e.g. line-load marking or ⇐. SAUDI ARABIAN STANDARD  SASO ……/2010 
 85.2 Additional information 
The following information shall be stated by the manufacturer, if applicable, e.g in the 
manufacturer’s data sheet or catalogue or on the packing unit: 
a) IEC 60947-7-3, if the manufacturer claims compliance with this standard; 
b) the rated cross-section; c) the rated connecting capacity, if different from table 2 of IEC 60947-7-1, including the 
number of conductors simultaneously connectable; 
d) the rated insulation voltage of the terminal block base and the fuse-carrier, if 
applicable; 
e) the working voltage or working voltage ran ge, primarily determined by the fuse-link or 
by additional components, e.g. illuminated indicators; 
f) rated impulse voltage; 
NOTE This value may be marked on the fuse terminal block only if the rated insulation voltage or the working 
voltage is also marked on the fuse terminal block, e.g. 250 V/4 kV or 250/4 kV. 
g) rated value of the power dissipation ( PV) and rated current of the fuse-link as declared 
by the manufacturer 
− in case of separate arrangement, 
− in case of compound arrangement; 
h) maximum power dissipation ( PVK) and rated current of the fuse-link 
− in case of separate arrangement, 
− in case of compound arrangement; 
i) operating conditions, if different from clause 6; 
j) size of the fuse-link. 
5.3 Marking on the packing unit 
a) “No overload protection” in case of fuse terminal blocks which are designed 
exclusively for short-circuit protection. 
b) “No overload protection in compound arrangement” in case of fuse terminal blocks 
which are designed for overload only in separate arrangement and short-circuit 
protection in compound arrangement. 
6 Normal service, mounting and transport conditions 
Clause 6 of IEC 60947-1 applies with the following addition. 
6.1.1 Ambient temperature 
The rated value of the power dissipation refers to an ambient temperature of 23 °C. 
In those cases where the ambient temperature differs from 23 °C, this fact shall be taken into 
account with respect to the function. See derating curves in annex B. SAUDI ARABIAN STANDARD  SASO ……/2010 
 97 Constructional and performance requirements 
7.1 Constructional requirements 
7.1.1 Clamping units 
Subclause 7.1.1 of IEC 60947-7-1 applies. 
7.1.2 Mounting 
Fuse terminal blocks shall be provided with means that allow them to be securely attached to 
a rail or a mounting surface. 
Tests shall be made in accordance with 8.3.2. 
NOTE Information on mounting rails can be found in IEC 60715. 
7.1.3 Clearances and creepage distances 
Clearances and creepage dist ances shall be designed for overvoltage category III and 
pollution degree 3. 
The requirements in accordance with IEC 60947-7-1 apply with the following additions. 
Clearances and creepage distances shall be checked where the fuse terminal block is 
assembled for normal use, e.g. fuse-carrier and gauge no. 3 or no. 6 is inserted in the terminal block base in accordance with table A.1. 
The following aspects shall be considered: 
a) functional insulation: 
− insulation between live parts with different potential; 
− insulation between live parts to adjacent  fuse terminal blocks of same type of 
construction and size; 
b) basic insulation: 
− insulation between live parts and the fixing support. 
Compliance is checked by measurement. Subclause 8.3.3.4 of IEC 60947-1 applies. 
7.1.4 Terminal identification and marking 
Subclause 7.1.4 of IEC 60947-7-1 applies. 
7.1.5 Void 
7.1.6 Rated cross-section and rated connecting capacity 
Subclause 7.1.6 of IEC 60947-7-1 applies. 
7.1.7 Void 
7.1.8 Actuating conditions 
The fuse terminal block shall be so designed that live parts are not accessible when it is 
assembled, installed and operated under normal use. SAUDI ARABIAN STANDARD  SASO ……/2010 
 10he safety from finger touch of live parts of the fuse-carrier shall be ensured during 
replacement of the fuse-link, unless otherwise specified by the manufacturer. The safety from 
finger touch shall be maintained until the fuse-carrier and the fuse-link are de-energized. 
7.2 Performance requirements 
7.2.1 Mechanical requirements during actuation 
Fuse terminal blocks shall have an adequate mechanical strength so as to withstand the 
stresses which occur during operation. 
Compliance shall be checked in accordance with 8.3.4 and 8.3.5. 
7.2.2 Electrical requirements 
7.2.2.1 Dielectric strength 
The dielectric strength shall be adequate. 
Verification shall be made by an impulse voltage test and a power-frequency withstand test on 
the fuse terminal block assembled by means of gauges as in normal use, in accordance with 8.4.3. 
7.2.2.2 Contact resistance 
The test shall be carried out in accordance with 8.4.4. If not otherwise specified, the mean 
value of the contact resistance shall not exceed 10 m Ω. The value of an individual 
measurement shall not exceed 15 m Ω. 
7.2.2.3 Temperature rise of clamping units 
The temperature rise of the clamping units shall not exceed 45 K. 
Compliance shall be checked in accordance with 8.4.5. 7.2.2.4 Electrical performance after ageing  
(for screwless-type fuse terminal blocks only) 
Fuse terminal blocks shall be capable of withstanding the ageing test comprising 192 
temperature cycles in accordance with 8.4.7. 
7.2.3 Thermal requirements 
7.2.3.1 Rated value of power dissipation 
A fuse terminal block shall be so designed that it can use a fuse-link with rated current and 
maximum sustained power dissipation, according to IEC 60127-1, lower or equal to the rated power dissipation value of the fuse terminal block and at an ambient air temperature of 23 °C 
(see annex B). 
In this way, the temperature of 85 °C on the surface of the actuating elements of the fuse-
carrier and the relative temperature index (RTI) of the insulating material as stated by the 
manufacturer in accordance with IEC 60216-1 shall not be exceeded. 
Compliance shall be checked in accordance with 8.5.2. SAUDI ARABIAN STANDARD  SASO ……/2010 
 11For fuse terminal blocks which are exclusively designed for short-circuit protection, the tests 
in accordance with 8.5.2.2 do not apply. 
Generally, the maximum permanent allowed temperature can be defined with a RTI value 
according to IEC 60216-1, based on 20 000 hours taking into account the electrical property. 
7.2.3.2 Durability 
Fuse terminal blocks shall be sufficiently resistant to therma l stresses which can occur under 
normal use. 
Compliance shall be checked in accordance with 8.5.3. 
7.2.3.3 Resistance to abnormal heat and fire 
The insulation materi als of fuse terminal bl ocks shall not be adversel y affected by abnormal 
heat and fire. 
Compliance shall be checked by the needle flame test, according to IEC 60695-2-2, as 
specified in 8.5.4. 
7.3 Electromagnetic compatibility (EMC) 
Subclause 7.3 of IEC 60947-7-1 applies. 
8 Tests 
8.1 Kinds of test Subclause 8.1 of IEC 60947-7-1 applies. 
8.2 General 
Subclause 8.2 of IEC 60947-7-1 applies with the following modification. The tests shall be carried out in the order as given in annex C. 
8.3 Verification of mechanical characteristics 
8.3.1 General 
The verification of mechanical characte ristics includes the following tests: 
− attachment of the fuse terminal block on its support (8.3.2); 
− mechanical strength of the clamping un its of a fuse termin al block (8.3.3); 
− compatibility between fuse terminal  blocks and fuse-link (8.3.4); 
− mechanical strength of the connection between the terminal block base and the fuse-
carrier (8.3.5). 
8.3.2 Attachment of the fuse terminal block on its support 
Subclause 8.3.2 of IEC 60947-7-1 applies. SAUDI ARABIAN STANDARD  SASO ……/2010 
 128.3.3 Mechanical properties of clamping units of a fuse terminal block 
8.3.3.1 Testing of mechanical strength of the clamping units 
Subclauses 8.2.4.1 and 8.2.4.2 of IEC 60947-1 apply with the following addition. 
The test of 8.2.4.2 of IEC 60947-1 applies to screwless-type clamping units accordingly. 
The test shall be made on two clamping units of five fuse terminal blocks mounted as in 
normal use on the appropriate support according to the manufacturer's instructions. 
For screw-type clamping units with a diameter of threads up to and including 2,8 mm, the 
tightening torque shall be in accordance with table C.1 of IEC 60947-7-1 or 110 % of 
the torque specified by the manufacturer, whichever is the greater. 
Rigid conductors of the rated cross-section shall be connected and disconnected five times. 8.3.3.2 Testing for damage to and accidental loosening of conductors  
of a fuse terminal block (flexion test) 
Subclause 8.3.3.2 of IEC 60947-7-1 applies. 
8.3.3.3 Pull-out test 
Subclause 8.3.3.3 of IEC 60947-7-1 applies. 
8.3.3.4 Verification of rated cross-section and rated connecting capacity 
Subclause 8.3.3.4 of IEC 60947-7-1 applies. 
8.3.4 Compatibility between fuse terminal blocks and the fuse-link 
The maximum gauge no. 1 or no. 4, in accordance with table A.1, shall be inserted and 
withdrawn 10 times from the fuse-carrier. 
Following each insertion of the gauge, the fuse-carrier shall be fitted to the terminal block 
base as in normal operation. In the case of fuse terminal blocks with screw-type fuse-carrier, 
the fuse-carriers shall be fitted wi th a torque of two-thirds of the value specified in table 1. 
Table 1 − Test forces 
Diameter ( d) of fuse carrier
Torque Axial pulling force
Nm N
0,4
0,625
50Up to and including 16 mm
Over 16 mm, up to and including 25 mm
∅d
 
 SAUDI ARABIAN STANDARD  SASO ……/2010 
 13No visible damage or loosening of parts shall be observed. The minimum gauge no. 2 or 
no. 5, according to table A.1, shall be prevented from falling out of the fuse-carrier in the most 
unfavourable position. 
The minimum gauge no. 2 or no. 5 shall then be inserted into the fuse terminal block and the 
contact resistance be measured according to 8.4.4 (see figure 1). 
The mean value of the contact resistance shall not exceed 10 m Ω. The value of an individual 
measurement shall not exceed 15 m Ω. 
8.3.5 Mechanical strength of the connection between the terminal block base  
and the fuse-carrier 
8.3.5.1 Torque test on screw-type fuse-carriers 
The fuse-carrier equipped with the maximum gauge no. 1 or no. 4, in accordance with 
table A.1, shall be screwed in five times in to the terminal block base by applying the 
respective torque specified in table 1. 
The fuse-carrier shall be securely kept in the terminal block base during and after the test, 
and shall show no changes impairing its normal use. 
8.3.5.2 Pull-out test on screw-type and bayonet-type fuse-carriers 
The fuse-carrier equipped with the maximum gauge no. 1 or no. 4, according to table A.1, 
shall be inserted in th e terminal block base. 
Screw-type fuse-carriers shall be tightened with a torque of two-thirds of the value specified in 
table 1. 
The fuse-carrier shall then be subjected to an axial pulling force as specified in table 1 for 
1 min. 
The fuse-carrier shall be securely kept in the terminal block base during and after the test, 
and shall show no changes impairing its normal use. 
8.3.5.3 Actuating forces on plug-on type or hinged-type fuse-carriers 
The fuse-carrier, together with the maximum gauge no. 1 or no. 4 according to table A.1, shall 
be inserted in and withdrawn from or slewed out of the terminal block base. 
The actuating forces shall be measured with appropriate measuring means. This test shall be 
conducted 10 times.  
The value of each individual measurement shall be within the limit values as stated by the 
manufacturer. 
The fuse-carrier shall be securely kept in the terminal block base during and after the test, 
and shall show no change impairing its normal use. SAUDI ARABIAN STANDARD  SASO ……/2010 
 148.4 Verification of electrical characteristics 
8.4.1 General 
The verification of electrical characteristics includes the following: 
− dielectric test (8.4.3); 
− contact resistance (8.4.4); 
− temperature-rise test of the clamping units (8.4.5); 
− ageing test for screwless-type fuse terminal blocks (8.4.7). 
8.4.2 Void 
8.4.3 Dielectric test 
8.4.3.1 General 
a) If the manufacturer has declared a value for the rated impulse voltage Uimp, the impulse 
withstand voltage test shall be made in accordance with 8.3.3.4.1, item 2), of  
IEC 60947-1, except item 2) c) which does not apply. 
b) According to the rated insulation voltage, the power-frequency withstand test shall be 
made in accordance with 8.3.3.4.1, item 3), of IEC 60947-1. 
The value of the test voltage shall be as stated in table 12A of IEC 60947-1 (see 8.3.3.4.1, 
item 3) b) i), of IEC 60947-1). 
8.4.3.2 Test arrangement and application of the test voltage 
8.4.3.2.1 General 
Each test shall be carried out on five adjacent fuse terminal blocks wired with conductors of 
the rated cross-section and installed on a metal support under the following conditions: 
– the conductor ends shall be stripped to a length specified by the manufacturer; 
– in case the manufacturer has stated the possibility of using different metal supports, the 
most unfavourable support shall be used. 
8.4.3.2.2 Test A 
Gauge no. 3 or no. 6, according to table A.1, shall be properly inserted as in normal use 
depending on the size of the fuse terminal block. Indicators, if any, shall be removed or 
disconnected during this test. 
Successively, the impulse withstand test vo ltage in accordance with the rated impulse 
withstand voltage Uimp at the considered fuse-carrier and the power-frequency withstand test 
voltage corresponding to the rated insulation voltage of the fuse-carrier shall be applied 
between the contact elements of each fuse terminal block. 
8.4.3.2.3 Test B 
Gauge no. 1 or no. 4, according to table A.1, shall be properly inserted as in normal use 
depending on the size of the fuse terminal block. SAUDI ARABIAN STANDARD  SASO ……/2010 
 15Successively, the impulse withstand test vo ltage in accordance with the rated impulse 
withstand voltage Uimp at the terminal block base and the power-frequency withstand test 
voltage corresponding to the rated insulation voltage of the terminal block base shall be 
applied between 
– the live parts of adjacent fuse terminal blocks of the same type and size; 
– the live parts of different polarity; – the live parts connected together and the support. 
8.4.3.3 Form and number of impulses 
The 1,2/50 µs impulse voltage shall be applied three times with intervals of at least 1 s 
between the individual pulses for each polarity. 
NOTE The output impedance of the pulse generator should not exceed 500 Ω. For the description of the test 
equipment, see IEC 61180-1 and IEC 61180-2. During these tests there should be no flashover or disruptive discharge. Corona effects or similar phenomena that do  not lead to a voltage breakdown are disregarded. 
8.4.4 Contact resistance 
8.4.4.1 General requirements for measurement 
The measurements may be carried out in direct or alternating current. In the case of 
alternating current measurements, the frequency shall not exceed 1 kHz. In case of doubt, the 
direct current measurements shall govern. 
The accuracy of the measuring apparatus shall be within ±3 %. 
The contact resistance shall be measured after the fuse terminal block has been equipped 
with gauge no. 2 or no. 5, according to table A.1. 
In the case of fuse terminal bl ocks with screw-type fuse-carriers,  the carrier shall be installed 
as in normal use with a torque equal to two-thirds of the value specified in table 1. 
Fuse terminal blocks with plug-on type or hinged-type fuse-carriers shall be installed as in 
normal use and tested in this condition. 
8.4.4.2 Measuring cycle and measurement performance 
8.4.4.2.1 General 
The contact resistance is normally calculated from the voltage drop measured according to 
figure 1. SAUDI ARABIAN STANDARD  SASO ……/2010 
 16mVMeasuring point
of voltage drop
Measuring point
of voltage dropGauge
no. 2 or no. 5
≤ 10 mm ≤ 10 mm
I
 
 
Figure 1 − Test arrangement for the verification of the contact resistance 
The complete measurement consists of five measuring cycles which shall be carried out 
successively. 
The measurement shall be made under the following conditions: 
a) test voltage: the open-circuit voltage of the current source shall not exceed 60 V d.c. or 
a.c. (peak value), but shall be at least 10 V; 
b) test current: 0,1 A; c) the measurement shall be made within 1 min following the application of the test current; d) the measurement shall be carried out so that unusual pressure on the contacts being 
tested and a displacement of the test conductors are avoided. 
8.4.4.2.2 Measuring cycle with direct current 
One measuring cycle comprises the following: 
a) insertion of the gauge in the fuse terminal block; 
b) measurement with current flowing in one direction; c) measurement with current flowing in the opposite direction; d) removal of the gauge from the fuse terminal block. SAUDI ARABIAN STANDARD  SASO ……/2010 
 178.4.4.2.3 Measuring cycle with alternating current 
One measuring cycle comprises the following: 
a) insertion of the gauge in the fuse terminal block; 
b) measurement; c) removal of the gauge from the fuse terminal block. 
8.4.4.3 Acceptance criteria 
The contact resistance shall not exceed the values according to 7.2.2.2. 
8.4.5 Temperature rise of clamping units 
Five fuse terminal blocks shall be installed side by side on a support a ccording to figure 1 as 
in normal use, together with the required accessories and the minimum gauge no. 2 or no. 5 inserted according to table A.1. 
Conductors and test currents shall be in accordance with 8.5.2.4. 
The conductors shall be tightened with the torque as specified in table 4 of IEC 60947-1, in 
accordance with the respective table C.1 of IEC 60947-7-1 for screw-type clamping units with a diameter of threads up to and including 2,8 mm, or with a higher torque as stated by the 
manufacturer. 
The test shall be carried out with single-phase a.c. current and continued until constant 
temperature values are reached. The temperature-rise limit values according to 7.2.3.3 at the 
conductor clamping units of the central fuse terminal block shall not be exceeded. 
8.4.6 Void 
8.4.7 Ageing test for screwless-type fuse terminal blocks 
The test is made simultaneously on five adjacent fuse terminal blocks equipped with gauges 
no. 2 or no. 5 according to table A.1, connected in series by conductors as specified in 8.5.2.4, as shown in figure 1. 
For fuse terminal blocks intend ed for use under “normal service conditions” (maximum 40 °C 
according to 6.1.1 of IEC 60947-1), PVC insulated conductors shall be used. 
For fuse terminal blocks for which the manufacturer has specified “maximum service 
conditions above 40 °C” (see 6.1.1, note 1 of IEC 60947-1), heat-resistant insulated or non-insulated conductors shall be used. 
The minimum length of the conductor bridges shall be 300 mm. 
The fuse terminal blocks are placed in a heating cabinet, which is initially kept at a tem-
perature of (20 ± 2) °C and then submitted to the verification of the contact resistance test. 
The whole test arrangement, including the conductors, shall not be moved until the contact 
resistance test has been completed. SAUDI ARABIAN STANDARD  SASO ……/2010 
 18The fuse terminal blocks are submitted to 192 temperature cycles as follows. 
The temperature in the heating cabinet is increased to 40 °C according to 8.3.3.3.1 of 
IEC 60947-1 or to the temperature value declared by the manufacturer for “maximum service conditions”. 
The temperature is maintained within ±5 °C of this value for approximately 10 min. 
During this test period the current according to 8.5.2.4 is applied. 
The fuse terminal blocks are then cooled down to a temperature of approximately 30 °C, 
forced cooling being allowed; they are kept at this temperature for approximately 10 min and, if necessary for measuring the voltage drop, it is allowed to cool down further to a tem-
perature of (20 ± 5) °C. 
NOTE As a guide, a value for the heating and cooling rate  of the heating cabinet of approximately 1,5 °C/min may 
be taken as a basis. 
The contact resistance on each terminal is also determined according to 8.4.4 after each of 
24 temperature cycles and after the 192 temperature cycles have been completed, each time 
at a temperature of (20 ± 5) °C. 
In no case the contact resistance shall exceed 15 m Ω or 1,5 times the value measured after 
the 24th cycle, whichever is less. 
If one of the fuse terminal blocks does not withstand the test, the test is repeated on a second 
set of fuse terminal blocks, all of which shall then comply with the repeated test. 
After this test, a visual inspection shall show no changes impairing further use such as 
cracks, deformations or the like. 
Furthermore, the pull-out test according to 8.3.3.3 shall be carried out. 
8.5 Verification of thermal characteristics 
8.5.1 General 
Verification of thermal characteristics includes the following: 
− rated value of the power dissipation (8.5.2); 
− durability (8.5.3); 
− needle-flame test (8.5.4). 
8.5.2 Rated power dissipation 
8.5.2.1 Test arrangements 
Two different test arrangements (separate arrangement and compound arrangement) shall be 
used for ascertaining the rated power dissipation of fuse terminal blocks. SAUDI ARABIAN STANDARD  SASO ……/2010 
 198.5.2.2 Test arrangement for the overload and short-circuit protection 
8.5.2.2.1 Separate arrangement 
A fuse terminal block, equipped with a dummy fuse-link of the power dissipation value of PV1 
according to table 2, acting as central terminal with four feed-through terminal blocks of the 
same type of construction and size, and with the necessary accessories (cover plate, end-
holder, etc.), shall be mounted on a support and connected in series with conductor loops 
according to 8.5.2.4. 
Dummy fuse-link
Temperature measurement
Feed-through
terminal block
Fuse terminal block
I 
Figure 2 − Test arrangement for separate arrangement 
 
8.5.2.2.2 Compound arrangement 
Five fuse terminal blocks shall be installed on  a support as in normal use together with the 
necessary accessories. 
The wiring shall be made as shown in figure 3 so that the power dissipation of the central fuse 
terminal block against the ex ternal fuse terminal blocks can be set ind ependently from 
another by separate current sources. 
The fuse terminal blocks shall be equipped with dummy fuse-links of the maximum power 
dissipation PV1 and PV2 in accordance with table 2. 
 SAUDI ARABIAN STANDARD  SASO ……/2010 
 20Dummy fuse-link of power
dissipation value PV2Dummy fuse-link of power
dissipation value PV1Temperature
measurementI
I
 
Figure 3 − Test arrangement for compound arrangement 
8.5.2.3 Test arrangement for exclusive short-circuit protection 
8.5.2.3.1 Separate arrangement 
Test arrangement according to 8.5.2.2, figure 2, equipped with dummy fuse-link of power 
dissipation value PV2. 
8.5.2.3.2 Compound arrangement 
Five fuse terminal blocks shall be installed on  a support as in normal use together with the 
necessary accessories. 
The wiring shall be made as shown in figure 4. All five fuse terminal blocks shall be equipped 
with dummy fuse-links of power dissipation value PV2 according to table 2. SAUDI ARABIAN STANDARD  SASO ……/2010 
 21Temperature
measurement
Dummy fuse-link of power
dissipation value PV2
I 
Figure 4 − Test arrangement for coumpound arrangement of short-circuit protection 
8.5.2.4 Wiring and test currents 
Conductors shall be connected to the fuse terminal blocks or adjacent feed-through terminal 
blocks as follows: 
a) length: 1 m; 
b) cross-section of a solid copper conductor: 
− 1 mm2 for fuse terminal blocks designed up to and including 6,3 A, test current 6,3 A; 
− 1,5 mm2 for fuse terminal blocks designed over 6,3 A up to and including 10 A, test 
current 10 A; 
− 2,5 mm2 for fuse terminal blocks designed over 10 A up to and including 16 A; test 
current 16 A; 
c) insulation: black. 
The conductors shall be tightened with the torque as specified in table 4 of IEC 60947-1, in 
accordance with the respective table C.1 of IEC 60947-7-1 for screw-type clamping units with a diameter of threads up to and including 2,8 mm, or with a higher torque as stated 
by the manufacturer. 
A thermocouple or another measuring method which has no essential influence on the 
temperature shall be applied for measuring the temperature of the part being tested. 
8.5.2.5 Dummy fuse-link for cartridge fuse-links 
A dummy fuse-link is a test cartridge fuse-link with a defined resistance according to table 2 
and dimensions within the tolerances for cartridge fuse-links.  
End cap material: brass, nickel plated; minimum thickness of nickel plating 2 µm. SAUDI ARABIAN STANDARD  SASO ……/2010 
 22Table 2 − Dummy fuse-links 
Size 
  
mm Maximum power dissipation values 
and associated resistance values Current 
c 
 
 
A Overload Nominal load 
PV1a R1d PV2b R2d 
W mΩ W mΩ 
 1,6 256 0,7 112 2,5 
5 × 20 1,6 40 0,7 18 6,3 
 2,5 63 1,0 25 6,3 
 4,0 101 1,3 33 6,3 
 1,6 1 600 0,5 500 1,0 
6,3 × 32 2,5 400 0,6 96 2,5 
 4,0 40 2,0 20 10,0 
a If other values are required, the values from t he basic series R10 of ISO 3 should be selected. 
b For nominal conditions derived from the rated current of the fuse-link multiplied with the voltage drop. 
c Values 10 A up to 16 A for cartridge fuse-links 5 mm × 20 mm are under consideration. 
d Tolerance ±10 %. 
8.5.2.6 Temperature measuring point 
The temperature shall be measured by approximation at the hottest point of the insulating part 
of the fuse terminal block ( TS2) and the surface of the actuating element of the fuse-carrier 
(TS1). In case of doubt, said points shall be determined by a preliminary test. 
8.5.2.7 Test procedure 
The dummy fuse-links provided for the test (separate arrangement and compound 
arrangement) shall be selected from table 2 and inserted into the fuse terminal block. 
The currents for the fuse terminal blocks being tested shall be so adjusted that the given 
maximum power dissipation values PV1 and/or PV2, according to table 2, are reached in 
conformity with the test arrangement of 8.5.2.2 and 8.5.2.3. The rated values shall remain 
constant during the whole testing duration. 
The test shall be continued until the temperature balance is reached. 
The temperature balance is reached when three successive readings, which shall be made at 
an interval of at least 5 min, do not show any further temperature rise. The measured results, 
determined at ambient temperature, shall be rectified to a reference temperature of 23 °C by 
means of a derating curve corresponding to the example shown in annex B. 
8.5.2.8 Acceptance criteria 
The temperature values measured shall not exceed the two values specified in 7.2.3.1. SAUDI ARABIAN STANDARD  SASO ……/2010 
 238.5.3 Durability 
Fuse terminal blocks shall be resistant to heat and mechanical stresses which are liable to 
occur in normal use. Moreover, the requirements of 8.5.2 shall be taken into consideration. 
Compliance with these requirements is checked by the following test. 
The fuse terminal block shall be subjected to the test for separate arrangement according to 
8.5.2.2.1 or 8.5.2.3.1, as applicable. The rated current related to the corresponding dummy 
fuse-link according to table 2 shall be passed through the test arrangement (see examples 
below). The test shall be carried out continuously over a period of 168 h. 
EXAMPLE 1  For an overload and short-circuit protection PV declared 2,5 W, 5 mm × 20 mm fuse-link: use a 
dummy fuse-link with 6,3 A and a power dissipation of 2,5 W.  
EXAMPLE 2  For an exclusively short-circuit protection PVK declared 2,5 W, 5 mm × 20 mm fuse-link: use a dummy 
fuse-link with 6,3 A and a power dissipation of 1 W. 
After the test, the fuse terminal block shall sh ow no changes impairing its function as in 
normal use. The following requirements shall be met: 
− dielectric test according to 8.4.3; 
− contact resistance test according to 8.4.4; the mean value shall not exceed 10 m Ω and the 
value of an individual measurement shall not exceed 15 m Ω; 
− compatibility test between fuse terminal block and fuse-link according to 8.3.4. 
8.5.4 Needle flame test 
The test is carried out according to IEC 60695-2-2 successively in the area of the fuse-link of 
three fuse terminal blocks. 
The test room shall be substantially draught-free with dimensions sufficient to ensure an 
adequate supply of air. 
Before the test, the fuse terminal blocks are stored for 24 h in an atmosphere having a tem-
perature between 15 °C and 35 °C and a relative humidity between 45 % and 75 %. 
After this preconditioning, the fuse terminal block is mounted on its appropriate support and 
fixed with suitable means so that one lateral insulation wall lies parallel to the layer placed 
below it (see figure 5). 
Conductors are not connected. 
The layer placed below, which consists of an approximately 10 mm thick pinewood board 
covered with a single layer of tissue paper (grammage between 12 g/m 2 to 30 g/m 2 
according to 6.86 of ISO 4046), is positioned at a distance of (200 ± 5) mm below the 
fuse terminal block. 
The test flame, adjusted in accordance with figure 1a) of IEC 60695-2-2, is guided under an 
angle of 45° to the la teral insulation wall. 
The tip of the flame shall make contact with the insulation wall in the area of the fuse-link (see 
figure 6). SAUDI ARABIAN STANDARD  SASO ……/2010 
 24The flame is applied for 10 s. For insulation walls <1 mm and/or an area <100 mm2, the flame 
is applied for 5 s. 
After the flame is removed, the duration of burning in the case of ignition is measured. 
Duration of burning denotes the time interval from the moment the flame is removed until 
flames or glowing of the fuse terminal block have extinguished. 
The fuse terminal blocks are considered to have passed the test if the duration of burning is 
<30 s in case of ignition. 
Moreover, the tissue paper on the pinewood board shall not ignite if burning or glowing 
particles fall from the fuse terminal block. 
Fuse terminal block
Lateral insulation wallSupport of the fuse terminal block
Fixing means
Tissue paper
Pinewood board
 
Figure 5 − Test arrangement for the needle flame test 
 
Fuse terminal block
Fixing means
Lateral insulation wall in the area
of the fuse-link45°
 
Figure 6 − Point of test flame contact (view from the layer  
placed below the fuse terminal block) SAUDI ARABIAN STANDARD  SASO ……/2010 
 258.6 Verification of EMC characteristics 
Subclause 8.6 of IEC 60947-7-1 applies. 
Annex A   
(normative) 
 
Gauges 
 
N6C
B
LTC
R0,5
∅D1∅D2
 
Figure A.1 – Outline of the gauges 
Table A.1 − Dimensions and materials for gauges for  
fuse-links according to IEC 60127-2 
Type of 
cartridge 
fuse-link 
mm Gauge 
No. Size L 
mm D1 
mm D2 
mm B 
mm Weight 
approx. 
 
g Material of part  
C T 
 
1 Max. 20,540,040
− 5,300,01+ 4,2 ± 0,1 500,1+ − Steel a 
5 × 20 2 Min. 19,4600,04+ 5,00,010
− 4,2 ± 0,1 500,1+ 2,5 Brass b 
 
3 − 20,540,040
− 5,300,01+ 4,2 
 6,200,1+ − Brass 
end 
caps b Glass or 
ceramic 
tube 
 
4 Max. 32,640,040
− 6,4500,01+ 5,5 ± 0,1 600,1+ − Steel a 
6,3 × 32 5 Min. 30,9600,04+ 6,250,010
− 5,5 ± 0,1 600,1+ 6 Brass b 
 
6 − 32,640,040
− 6,4500,01+ 5,5 
 8,300,1+ − Brass 
end 
caps b Glass or 
ceramic 
tube 
NOTE All test gauges are without a melting element. 
a Hardened. 
b Copper content from 58 % to 70 %. 
NOTE This table is taken from IEC 60127-6. 
The gauges or their parts made from brass shall be coated with a nickel layer of 8 µm and 
a gold layer of 4,5 µm. 
The end of the gauges shall have no holes. SAUDI ARABIAN STANDARD  SASO ……/2010 
 26The gauges shall have a homogenous composition, except for gauges no. 3 and no. 6. 
 
Annex B   
(informative) 
 
Power dissipation values PV and PVK 
 
 
B.1 Ascertainment of the rated power dissipation  
values PV and PVK of fuse terminal blocks 
The ascertainment of the rated power dissipation for the exclusive short-circuit protection of 
PVK takes into consideration the fact that fuse te rminal blocks in circuits where no overload is 
liable to occur are loaded only with the maximum power dissipation of the cartridge fuse-link 
under nominal conditions of PV2. 
The assignment of a rated power dissipation of the fuse terminal block in the event of short 
circuit PVK to the maximum powe r dissipation value PV1 of the cartridge fuse-links is 
necessary because only the maximum sustained power dissipation value of PV1 is defined in  
IEC 60127-2 for cartridge fuse-links under overload conditions. 
B.2 Design of the derating curves 
The surface temperatures TS1 and TS2 of the sample, determined during the test, and the ambient 
temperature TA during the test are taken as a basis for the design of the derating curve. 
An auxiliary line is plotted in parallel to the X-axis of a coordinate system at the level of the 
maximum power dissipation ( PV1) of the dummy fuse-link. 
Also in the case of the test for the exclusive short-circuit protection, an auxiliary line ( PV1) is 
plotted in parallel to the X-axis for the correlated PV2-value according to table 2 instead of an 
auxiliary line ( PV2). 
The ambient temperature TA, the reference temperature of 23 °C, the maximum surface 
temperature of the accessible parts of 85 °C according to 7.2.3.1 and the RTI value of the 
insulating material are marked on the X-axis. 
During the test according to 8.5.2 the temperature rise ∆TS1 = TS1 – TA is measured, with TS1 
= maximum measured temperature at the accessible parts, measured at an arbitrarily selected 
ambient temperature TA (example in the drawings TA = 22 °C). 
The maximum permissible ambient temperature T1, at which the maximum permissible 
temperature of the accessible parts (85 °C) will not be exceeded, if the fuse terminal block is 
operated with the full power defined by the used dummy, is now calculated by subtraction of 
the measured ∆TS1 value from that maximum permissible temperature of the accessible parts 
(85 °C): 
T1 = 85 °C – ∆TS1 = 85 °C – (TS1 – TA ) SAUDI ARABIAN STANDARD  SASO ……/2010 
 27A vertical line through T1 cuts the auxiliary line PV1 at that point X1, from which a straight line 
is drawn to the 85 °C point on the X-axis. The area below this line defines the operating 
conditions at which the maximum permissible temp erature of the accessible parts (85 °C) will 
not be exceeded. 
It is proceeded by analogy with the ascertained maximum surface temperature of the 
insulating material ( TS2). 
The maximum permissible ambient temperature 
T2 = RTI – ∆TS2 = RTI – (TS2 – TA ) 
is obtained from the measured maximum surface temperature TS2 of the insulating material, 
the RTI value dependent on the insulating material and the ambient temperature TA. 
A straight line between the RTI value on the X-axis and T2 on the auxiliary line (cutting 
point X2) defines the operating conditions belo w which the maximum permissible temperature 
of the insulating materi al will not be exceeded. 
B.3 Evaluation 
The area below the bold-type limit lines in the examples defines the area in which are found 
the acceptable values of the maximum sustained dissipation (according to IEC 60127-1) of the cartridge fuse-link installed in the fuse terminal block. 
The test, that correctly defines limit lines, uses a maximum power dissipation of a dummy 
fuse-link, which leads to surface temperatures as close as possible to RTI value for T
S2 and 
to 85 °C for TS1. Several tests may be necessary to find the dummy fuse-link defined in 
table 2.  
If one of the limit lines intersects the auxiliary line ( PV1) beyond 23 °C (reference tempe-
rature), the test is then repeated with a dummy fuse-link of the next smaller value of the maximum power dissipation. 
If the intersections of the limit lines with the re ference temperature of 23 °C lie, however, far 
above the auxiliary line ( P
V1), it may be checked, where applicable, whether the fuse terminal 
block meets the requirements of a dummy fuse-link with the next higher value of the maximum power dissipation. 
B.4 Examples 
B.4.1 Example 1 – Field of application: exclusive short-circuit protection ( PVK) SAUDI ARABIAN STANDARD  SASO ……/2010 
 28B.4.1.1 Separate arrangement 
PV1=4 , 0  W T1= 85 °C – ∆TS1
PV2=1 , 3  W = 85 °C – (TS1 – TA)
RTI = 110  °C = 39 °C
TA= 22 °C
TS1= 68 °C T2= RTI – ∆TS2
TS2= 105  °C = RTI – (TS2 – TA)
PVK=4 , 2  W = 27 °CTemperature
measurementDummy fuse-link of
power dissipation
value Pv2
I
X2 X1
Pvk = 4,2  W4,0
3,5
3,0
2,5
2,01,5
1,00,5
0
0 10 20 30 40 50 60 70 80 90 100 110 120
∆TS1∆TS2
23
TA = 22T2 = 27T1 = 39(Auxiliary line Pv1)
RTIPower dissipation P   W
Ambient air temperature T   °C
 
Key 
PV1 Maximum power dissipation of the cartri dge fuse-link under overload conditions 
PV2 Maximum power dissipation of the cartridge fuse-link under rated conditions 
RTI Relative temperature index 
TA Ambient temperature 
TS1 = TA + ∆TS1 (measured temperature at the accessible insulation material surface) 
∆TS1 Measured temperature rise at the accessible insulation material surface 
TS2 = TA + ∆TS2 (measured temperature at the hottest point of the insulation material surface) 
∆TS2 Measured temperature rise at the hottest point of the insulation material surface 
PVK Exclusive short-circuit protection (see 4.2.2)  
T1 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
accessible parts (85 °C) will not be exceeded if the fuse  terminal block is operated with the full power as 
defined by the used dummy SAUDI ARABIAN STANDARD  SASO ……/2010 
 29T2 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
insulation material (RTI) will not be exceeded if the fuse  terminal block is operated with the full power as 
defined by the used dummy 
Figure B.1 – Derating curve in the case of exclusive short-circuit protection  
for a separate arrangement 
B.4.1.2 Compound arrangement 
PV1=2 , 5  W T1= 85 °C – ∆TS1
PV2= 1,0 W = 85 °C – ( TS1 – TA)
RTI = 110 °C = 47 °C
TA= 20 °C
TS1= 58 °C T2= RTI – ∆TS2
TS2= 93 °C = RTI – (TS2 – TA)
PVK= 2,9 W = 37 °CTemperature
measurement
Dummy fuse-link of
power dissipation
value Pv2I
X2X1
(Auxiliary line Pv1)Power dissipation P   W
3,0
2,5
2,01,5
1,0
0,5
0
0 10 20 30 40 50 60 70 80 90 100 110 120∆TS1∆TS2
23
TA = 20T2 = 37 T1 = 47RTI
Ambient air temperature T   °CPvk = 2,9 W3,54,0
 
Key 
PV1 Maximum power dissipation of the cartri dge fuse-link under overload conditions 
PV2 Maximum power dissipation of the cartridge fuse-link under rated conditions 
RTI Relative temperature index 
TA Ambient temperature 
TS1 = TA + ∆TS1 (measured temperature at the accessible insulation material surface) 
∆TS1 Measured temperature rise at the accessible insulation material surface 
TS2 = TA + ∆TS2 (measured temperature at the hottest point of the insulation material surface) 
∆TS2 Measured temperature rise at the hottest point of the insulation material surface 
PVK Exclusive short-circuit protection (see 4.2.2) SAUDI ARABIAN STANDARD  SASO ……/2010 
 30T1 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
accessible parts (85 °C) will not be exceeded if the fuse  terminal block is operated with the full power as 
defined by the used dummy 
T2 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
insulation material (RTI) will not be exceeded, if the fu se terminal block is operated with the full power 
as defined by the used dummy. 
Figure B.2 – Derating curve in the case of exclusive short-circuit protection  
for a compound arrangement SAUDI ARABIAN STANDARD  SASO ……/2010 
 31Usable cartridge fuse-links 1 5 mm x 20 mm, in accordance with IEC 60127-2, in a fuse 
terminal block with the ascertained rated power dissipation value of PVK = 4,2 W in separate 
arrangement and PVK = 2,9 W in compound arrangement for the exclusive short-circuit 
protection. 
Table B.1 – Results of derating curves in the case of exclusive short-circuit protection 
 Field of application 
Arrangement Exclusive short-circuit 
protection Overload and short-circuit 
protection 
 Max. TA Nominal values Max. TA Nominal values 
Separate 
Compound 27 °C 
37 °C 4 W/6,3 A 
2,5 W/6,3 A − 
− − 
− 
 
___________ 
1 Where non-standardized cartridge fuse-links are used, the power dissipation of the fuse-link shall not exceed the 
rated value of PV and/or PVK of the fuse terminal block (reference temperature 23 °C). In the case of higher 
ambient temperatures the maximum permissible power di ssipation shall be derived from the derating curve. SAUDI ARABIAN STANDARD  SASO ……/2010 
 32B.4.2 Example 2 −Field of application:  
Overload and short-circuit protection ( PV) 
B.4.2.1 Separate arrangement 
PV1=2 , 5  W T1= 85 °C – ∆TS1
PV2= 0,6 W = 85 °C – ( TS1 – TA)
RTI = 120 °C = 36 °C
TA=2 5  ° C
TS1=7 4  ° C T2= RTI – ∆TS2
TS2= 103,5 °C = RTI – (TS1 – TA)
PV= 3,1 W = 41,5 °CTemperature
measurementDummy fuse-link of
power dissipation
value Pv1
IPower dissipation P   W Pv = 3,1 W
3,0
2,5
2,0
1,51,0
0,5
0
0 10 20 30 40 50 60 70 80 90 100 110 120
23
T
A = 25T2 = 41,5
T1 = 36RTI
Ambient air temperature T   °CX1
(Auxiliary line Pv1)
∆TS1∆TS2X2
Key 
PV1 Maximum power dissipation of the cartri dge fuse-link under overload conditions 
PV2 Maximum power dissipation of the cartridge fuse-link under rated conditions 
RTI Relative temperature index 
TA Ambient temperature 
TS1 = TA + ∆TS1 (measured temperature at the accessible insulation material surface) 
∆TS1 Measured temperature rise at the accessible insulation material surface 
TS2 = TA + ∆TS2 (measured temperature at the hottest point of the insulation material surface) 
∆TS2 Measured temperature rise at the hottest point of the insulation material surface 
PV Overload and short-circuit protection (see 4.2.1) 
T1 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
accessible parts (85 °C) will not be exceeded if the fuse  terminal block is operated with the full power as 
defined by the used dummy SAUDI ARABIAN STANDARD  SASO ……/2010 
 33T2 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
insulation material (RTI) will not be exceeded if the fuse  terminal block is operated with the full power as 
defined by the used dummy 
Figure B.3 – Derating curve in the case of overload and short-circuit protection  
for a separate arrangement 
B.4.2.2 Compound arrangement 
PV1=1 , 6  W T1= 85 °C – ∆TS1
PV2= 0,5 W = 85 °C – ( TS1 – TA)
RTI =1 2 0  ° C =  3 0  ° C
TA=2 0  ° C
TS1=7 5  ° C T2= RTI – ∆TS2
TS2=9 9  ° C =  RTI – (TS2 – TA)
PV= 1,8 W = 41 °CTemperature
measurementDummy fuse-link of
power dissipation
value Pv1Power dissipation P   W
Pv = 1,8 WX1
(Auxiliary line Pv1)X23,0
2,5
2,0
1,5
1,0
0,5
0
0 10 20 30 40 50 60 70 80 90 100 110 120
23
TA = 20T2 = 41T1 = 30RTI
Ambient air temperature T   °C∆TS1∆TS2I
IDummy fuse-link of
power dissipation
value Pv2
Key 
PV1 Maximum power dissipation of the cartri dge fuse-link under overload conditions 
PV2 Maximum power dissipation of the cartridge fuse-link under rated conditions 
RTI Relative temperature index 
TA Ambient temperature 
TS1 = TA + ∆TS1 (measured temperature at the accessible insulation material surface) 
∆TS1 Measured temperature rise at the accessible insulation material surface 
TS2 = TA + ∆TS2 (measured temperature at the hottest point of the insulation material surface) 
∆TS2 Measured temperature rise at the hottest point of the insulation material surface SAUDI ARABIAN STANDARD  SASO ……/2010 
 34PV Overload and short-circuit protection (see 4.2.1) 
T1 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
accessible parts (85 °C) will not be exceeded if the fuse  terminal block is operated with the full power as 
defined by the used dummy 
T2 Maximum permissible ambient temperature, at wh ich the maximum permissible temperature of the 
insulation material (RTI) will not be exceeded if the fuse  terminal block is operated with the full power as 
defined by the used dummy 
Figure B.4 – Derating curve in the case of overload and short-circuit protection  
for a compound arrangement 
Usable cartridge fuse-links 2 6,3 mm × 32 mm, in accordance with IEC 60127-2, in a fuse 
terminal block with the ascertained rated power dissipation value of PV = 3,1 W in separate 
arrangement and PV = 1,8 W in compound arrangement for overload and short-circuit 
protection.” 
Table B.2 – Results of derating curves in case of overload and  
short-circuit protection 
 Field of application 
Arrangement Exclusive short-circuit  
protection Overload and short-circuit 
protection 
 Max. TA Nominal values Max. TA Nominal values 
Separate 
Compound − 
− − 
− 36 °C 
30 °C 2,5 W/2,5 A 
1,6 W/1,0 A 
  
  
 
 
 
  
 
  
 
 
___________ 
2 Where non-standardized cartridge fuse-links are used, the power dissipation of the fuse-link shall not exceed the 
rated value of PV and/or PVK of the fuse terminal block (reference temperature 23 °C). In the case of higher 
ambient temperatures, the maximum permissible power dissipation shall be derived from the derating curve. SAUDI ARABIAN STANDARD  SASO ……/2010 
 35Annex C   
(normative)  
 
Order of tests and number of specimens 
  
Table C.1 – Order of tests and number of specimens 
Test 
group Test 
no. Number of 
specimens Test According to
subclause 
1 1.1 1 Marking 5.1 
2 2.1 
2.2 
2.3 5 Clearances and creepage distances 
Dielectric tests 
Attachment of the fuse 
terminal block on its support 7.1.3 
8.4.3 
8.3.2 
3 3.1 
3.2 5 Contact resistance 
Compatibility between fuse terminal blocks and fuse-
link 
Mechanical strength of the connection 
between the terminal block base and the fuse-carrier 
Mechanical properties of clamping units of a fuse 
terminal block 8.4.4 
8.3.4 
 
8.3.5 
 
 
8.3.3 
4  
4.1 
 
 
4.2  
1 separate/ 
5 compound 
arrangement 
1 separate/ 
5 compound 
arrangement Rated power dissipation 
a) overload and short-circuit protection 
 
 
b) exclusive short-circuit protection 8.5.2 
8.5.2.2 
 
 
8.5.2.3 
5 5.1 3 Durability 8.5.3 
6 6.1 5 Temperature rise of clamping units 8.4.5 
7 7.1 5 Ageing test for screwless-type fuse terminal blocks 8.4.7 
8 8.1 3 Needle flame test 8.5.4 
NOTE Additional feed-through terminal blocks of same  type of construction and size may be necessary to 
accommodate test arrangements. SAUDI ARABIAN STANDARD  SASO ……/2010 
 36Bibliography 
 
IEC 60127-6:1994, Miniature fuses – Part 6: Fuse-holders for miniature cartridge fuse-links 
IEC 60364-4-43:2001, Electrical installations of buildings – Part 4: Protection for safety – 
Chapter 43: Protection against overcurrent   
IEC 60715:1981, Dimensions of Iow-voltage switchgear and controlgear – Standardized 
mounting on rails for mechanical support of electrical devices in switchgear and controlgear 
installations  Amendment 1 (1995) 
IEC 61180-1:1992, High-voltage test techniques for low-vol tage equipment – Part 1: Definitions, 
test and procedure requirements  
IEC 61180-2:1994, High-voltage test techniques for low-voltage equipment – Part 2: Test 
equipment 
 
 
__________