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Posted By Topic: Sub Circuit Arrangement

Apr 05 2013 15:31

Hi Guys,
I am working as a consulting engineer in Australia and found this forum very interesting.
I am in a situation where a three phase circuit breaker in a distribution board is feeding another distribution board through an isolator. Now I want to feed a mechanical control panel in the same room where the isolator is and I want to avoid the situation running a new circuit from the distribution board to the mechanical control panel, instead I want to tap off the existing isolator. Is this situation allowed according to AS/NZS 3000? If no, is there any other alternative way to do it except running a new circuit from the distrution board?
I have attached a copy of the sketch of what I am trying to say. hope it makes sense.

Apr 06 2013 12:55

Yes there will be a way - probably several ways - of doing it; but the details depend on many factors.

I could ask a lot of questions to get the info needed: location of isolator, whether PEC or PEN submain, size & type of submain cable. existing load and load of what's being added, space avalable in DB, etc, etc.

But as a consulting engineer, you should be able to read and apply the Wiring Rules without seeking free design advice from hard-working sparkies. Surely that's what you're being paid for?


Apr 07 2013 07:20

Careful how much info you give out Alec he will cut and paste it into his next specification