Code/best practice on 60C & 90C wire in same EMT conduit?
If pulling new/replacement THWN (90C) conductors through an existing (old work) conduit, containing old 60C (TW) conductors, are the old wires "grandfathered", or is there some mandate to upgrade all conductors in that "raceway"?
I'm "a-guessin'" that the 60C wires can be left in place, but all conductors in that conduit have to be de-rated per 60C tables... yes/no/elaborate/please enlighten the ig-nernt?
Thanks in advance... assiduously rectifying jury-rigged wiring that would make even Pharkus go... Mr. Bill! =:O