derating factors

[thekingtut]

what are the derating factors according to NEC that should i take into consideration when i make adesign of cable some manufactures said that many derating factors should be considard like grouping factor ,air temp. , ground thermal risistivity....etc,
thanks alot

 

[Dennis Alwon]

Look at article 310.15 in total but esp. 310.15(B)(2). See if that helps