James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
I installed a 3ph 400a service - outside CT cabinet, CTs, meter can, inside MB panel. Existing conduit is 3" PVC. Considering pipe size, I fed it with (4) 500kcmil aluminum (ATHHN). However, the wire is not rated at 400 amps, so I had the trip unit changed to 300 amps. The breaker itself is marked 400 amp, but the trip unit is clearly marked 300 amp. Total connected load will be about 160 amps. My issue is that the inspector declared it to be a 400 amp service because the labels show that main breaker and buss are rated at 400 amps. He insists that I change he cable to 500kcmil copper, a pretty expensive upgrade. I tried to explain that it is akin to using a 60 amp disconnect with 40 amp fuses in it, and feeding it with 8 gauge wire. Yet he would not budge that I installed a 400 amp service. Is there any issue with having a 400 amp label on the breaker casing, while though the trip unit is marked 300 amp?