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 Cable Derating (Factors).
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.