Table 310.13 lists THHW and XHHW as 90C for dry locations and 75C for wet locations.
When de-rating conductor ampacity for conduit fill and/or temperature,is it permissible to use the 90C rating in a wet application and apply the de-rating factors as long as the 75C rating is not exceeded? OR must you use the 75C rating and apply the de-rating factors for selecting the proper conductor.
When de-rating conductor ampacity for conduit fill and/or temperature,is it permissible to use the 90C rating in a wet application and apply the de-rating factors as long as the 75C rating is not exceeded? OR must you use the 75C rating and apply the de-rating factors for selecting the proper conductor.