I have a 1200 amp disco single phase that can have up to (4) 500 mcm feeds per line. Trying to use aluminum wiring to reduce cost and from the general ampacity chart THHN aluminum wire is rated for 90c and 350 amps. However I will have the maximum of 6 wires per 4" schedule conduit x2. Do I need to derate? If I derate I would need to use 600 mcm aluminum or switch to copper but my understanding is they make these things to work with aluminum or copper wiring.
Help calculating service feed 1200 amp
- Thread starter waes
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes with 6 CCC's in each raceway you'll need to derate the conductor ampacity to 80%. If you use a 90° C conductor like THHN you can use the 90° C ampacity for your derating. 500 kcmil Al is too small (350*80%*4 sets=1120 amps). You'll need a minimum of 600 kcmil Al. (385*80%*4 sets=1232 amps)
- Status