Use the link on the left to access our cable sizing application. Manage and size all your cables, from low voltage to 33 kV.
Many countries and organisations produce cable sizing standards. Standards, allow engineers to size cables with a consistent approach. Using a standard also gives the engineer a fullback with which to validate any design should the need arise.
myCableEngineering incorporates the following sustained current sizing standards:
BS 7671 is the UK requirements for electrical installations standard, also known as the Wiring Regulations. Appendix 4 (BS 7671:2018) gives guidance determining the current capacity and voltage drop for cables.
Cable current capacity calculations in BS 761 are based on the derating factor method, see . The derating tables have been derived from IEC 60287 and aligned with IEC 60364 (although there is some fundamental difference).
The parameters considered in the standard are, ambient temperature, soil thermal resistivity, the installation methods and grouping of cables.
ERA 69-30 sustained current ratings is a nine-volume set of recommendations, published by Edif ERA. The calculation of cable rating follow the derating factor method, see .
ERA is a UK based organisation, and these standards reflect this. The user of ERA is particularly popular amongst DNO (district network operators) and supply authorities.
Each volume covers a particular cable type, for example, part V is for 600/100 V and 1900/33000 V cables with thermosetting insulation. Typically the recommendation cover both three-phase a.c. 50 Hz and d.c. are for in air and buried cable installations.
In addition to current capacity, the recommendations provide estimates of power dissipation and a guide to average soil temperatures within the UK.
IEC 60502 is an International Electrotechnical Commission standard, which gives current ratings for medium voltage cables. The calculation of cable rating follow the derating factor method, see .
The IEC 60502 standard is in two parts; part 1 for voltages up to 1 kV and part 2 for voltages from 1 kV to 30 kV. Part 1 does not contain any current capacity sizing, as this is intended to be covered by IEC 60364. Part 2 Annex B, has a calculation method for determining current capacities for voltages covered by this part.
The current rating tables include three phase cables both installed in the air and buried. Derating factors considered are the ambient temperature, depth of laying and soil thermal resistivity for buried cables, and the grouping of cables.