ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Ok consider a commercial rooftop system with 450 amps of inverter output current. I am using a larger system because it will have higher utility fault currents whereas a resi system may not have an issue. I come down off the roof with inverter output circuits to a combiner panelboard on the side of the building. Next to that I have a non fused disco. The panelboard and disco are 600 A. After the disco, the feeder goes through the exterior wall into the electrical room where it connects to the interconnect breaker (supply or load side, shouldn't matter for this discussion). The SCCR of the switch is 10k with this configuration. This is likely too low and a code violation. Do you agree with this or do you think my reasoning is incorrect?
Can you point me to the language in the NEC where you think the violation lies? I think this scenario does not address the issue at least as far as the ampere rating of the switch is concerned, since 450A is too much for even a 100% rated 400A switch and 600A (the next size up) is more than 125% of 450A. If your inverter output were 380A, the question would be if a 400A unfused switch would suffice, or would you have to use a 600A switch. I maintain that the 400A switch would be sufficient.