There is an old (1960's) unfused 600 amp disconnect fed with parrallel 500's. We are looking to replace the switch. I was wondering what type of insulation was used back then. I should send a picture of the wire. For an amperage rating of these wires, can I use the left coloumb (310.15(B)(16) in the NEC (60c-TW), to play it safe? I know that table will give it a lower rating, plus I have to derate 70%. It's 6" gal, with 6-500's, and 2-250's for the nuetral. Thanks, SJT
I guess I was really just trying to establish a column in 310.16 I agree the insulation did not look like TW. I used to have a piece of 750 MCM under the seat of my car as a persuader in serious social situations.
I don't know where that piece of 750 is now. I gave it to my old buddy who was a cable splicer for Ma Bell. He planned on stripping it, dipping the fluxed strands in a lead pot and making a big lead head mace like you make a candle.