IEC 60695-1-10:2009 pdf download – Fire hazard testing – Part 1-10: Guidance for assessing the fire hazard of electrotechnical products – General guidelines
3.9
quantitative fire test
fire test which takes into account the circumstances of product use in which the testconditions are based on, or are relatable to, the circumstances of use of the test specimen,and which measures a parameter or parameters， expressed in well defined terms and usingrational scientific units,which can be used in the quantitative assessment of fire risk
3.10
reaction to fire
response of a test specimen when it is exposed to fire under specified conditions in a fire test
NOTE Fire resistance is regarded as a special case and is not normally considered as a ‘reaction to fire’ property.[ISO/IEC13943, definition 4.272]
3.11
real-scale fire test
fire test that simulates a given application, taking into account the real scale, the real way theitem is installed and used, and the environment
NOTE Such a fire test normally assumes that the products are used in accordance with the conditions laid downby the specifier and/or in accordance with normal practice.
[ISO/IEC 13943,definition 4.273]
3.12
small-scale fire test
fire test performed on a test specimen of small dimensions
NOTE A fire test performed on a test specimen of which the maximum dimension is less than 1 m is usually calleda small-scale fire test.
[SOIEC 13943, definition 4.292]
4Fire hazards associated with electrotechnical products
The transmission，distribution，storage and utilization of electrical energy can have thepotential to contribute to fire hazard.
With electrotechnical products the most frequent causes of ignition are overheating and arcing. The likelihood of ignition will depend on the product and system design, the use of safety devices and systems, and type of materials used. Electrotechnical products, when operating, generate heat and in some cases arcing and sparking are normal phenomena. These potential risks should not lead to hazardous conditions provided that they have been taken into account initially at the design stage, and subsequently during installation, use and maintenance. Although it is a commonly held belief that most electrical fires are caused by a short-circuit, there are many other possible causes of ignition.
These can include improper installation, improper utilization and inadequate maintenance. Examples are: operation under overload for temporary or extended periods; operation under conditions not provided for by the manufacturer or contractor; inadequate heat dissipation; and faulty ventilation.
Table 1 lists common ignition phenomena encountered in electrotechnical products. Unless otherwise indicated, the sources of ignition are considered to be internal to the electrotechnical product.
It includes the most frequently encountered cases. The sequence indicated is not related to the magnitude or frequency of occurrence. Fires involving electrotechnical products can also be initiated from external non-electrical sources. Hazardous conditions, which do not arise from the use of the electrotechnical product itself, can and often do involve that product. Considerations of this nature are dealt with in the overall hazard assessment, individual product safety standards, or for example by the provisions of IEC/TS 62441 .
When designing products, the prevention of ignition in normal and abnormal operating conditions requires a higher priority compared to minimizing eventual spread of flames. After ignition has occurred, for whatever reason, the effects of the subsequent fire must be assessed. Factors to be taken into account include:
a) fire growth and flame spread;
b) heat release;
c) smoke generation (visibility);
d) production of toxic fire effluent;
e) production of potentially corrosive fire effluent;
f) the potential of explosion.
References to TC 89 guidance on items a) through f) can be found in Clause 9.
