Point of connection

J-low · May 22, 2013

On my previous commercial installs 10kw plus I have always taken my AC back to the main section board, I am currently planning an install that has a three phase sub DB next to my panel/ inverter position 80m from the section board. Can I connect to the sub DB? I can't think of a reason why not, though it doesn't feel like the best practice it will help me recoup money lost due to panel increases!

jason121 · May 22, 2013

losses in cable versus cost for new cable, labour and Volt drop

Gavin A · May 22, 2013

assuming the cable is of a suitable size to minimise volt drop back to the incomer, then it'd be pointless expense to run a new cable in - make sure you label up correctly at both boards though.

Earthstore · May 22, 2013

Just one question, Gavin may answer this, Is the sub board protected by an RCD at the main?

Gavin A · May 22, 2013

Earthstore said:
Just one question, Gavin may answer this, Is the sub board protected by an RCD at the main?

I'm not psychic, but did assume it wouldn't be as I've personally never come across RCD protection on 3 phase outside of farms, sure it does happen though, and it's a fair question.

I'd assume the sub main will be run in SWA, so not needing RCD protection as you'd not really want an RCD to trip the entire sub main board that was located 80m away in another building.

so I suppose I probably have answered the question and explained my assumption.

Must do some work or something eh.