400amp building service , #500 copper. load below 380A
- Thread starter Cartoon1
- Start date
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Yes. At 380 amps it is above the calculated load of 350 amps so the next size up rule to 400 amps (the next standard size up from 380 amps) is permitted.
Even if those cables are coming from the secondary side of transformer feeding the 400amp service main correct?
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
The transformer is in the utility size upstream of the service point?
utility Transformer feeding the building. 400amp main service meter.
If they are service conductors from a utility transformer you are allowed the "next size up rule"; if they are secondary conductors form customer transformer you are not allowed to use the next size up rule.
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
What Augie said. 
Thank you!!!! Boss answer haha. Yes, it is utility transformer secondary not owner owned transformer. So #500 is sufficient in this case.
Thank youWhat Augie said.
