What is BS IEC 60287-3-1- Site reference conditions for electric cables about?
BS IEC 60287 is an international standard on electric cables and the calculation of the current rating.
BS IEC 60287-3-1 is applicable to the conditions of steady-state operation of cables at all voltages, buried directly in the ground, in ducts, troughs, or in steel pipes, both with and without partial drying-out of the soil, as well as cables in the air.
The term "steady-state" is intended to mean a continuous constant current (100 % load factor) just sufficient to produce asymptotically the maximum conductor temperature, the surrounding ambient conditions being assumed constant.
Who is BS IEC 60287-3-1 - Site reference conditions for electric cables for?
BS IEC 60287-2-3 on calculation of the current rating is relevant to:
- Cable manufacturers
- Cable installation designers
- Electrical cable and equipment stockists and suppliers
- National and local authorities
- Regulatory bodies
Why should you use BS IEC 60287-3-1 - Site reference conditions for electric cables?
In order to use the formulae given in the various parts of IEC 60287, numerical values for the physical quantities should be chosen relating to the operating conditions. The quantities related to the operating conditions of cables are likely to vary considerably from one country to another.
BS IEC 60287-3-1 contains reference ambient temperatures and thermal resistivities of soil in various countries. Values relating to the operating conditions such as thermal characteristics of the soil, depth of laying of cables and air ambient temperature are provided.
Numerical values should preferably be based on results of suitable measurements. Often such results are already included in national specifications as recommended values, so that the calculation may be based on these values generally used in the country in question; a survey of such values is given in BS IEC 60287-3-1.
As quantities related to the operating conditions of cables are liable to vary considerably from one country to another, BS IEC 60287-3-1 can help cable installation designers ensure their products can meet the performance requirements as per national values.
What’s changed since the last update?
BS IEC 60287-3-1:2017 replaces the first edition published in 1995 and amendment 1:1999. This edition includes the following significant technical changes with respect to the previous edition:
- The updated list of national laying conditions is now covered in Annex A
- Clause 5 about the information required from the purchaser for the selection of the appropriate type of cable has been removed
