Published: 13 August 2009
Category: Q&A
Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, concerning domestic sub-main topics, is answered by SELECT:
Question: I have a couple of sub-main questions:
1) Does a sub-main have to have an isolator at the origin, ie - where it leaves the consumer unit or distribution board?
2) Could it still be classed as a sub-main if it comes off a spare circuit breaker - say 63A - in domestic consumer unit?
Answer: A sub-main is now termed a distribution circuit and:
1) If it is more than 3m in length, the cable should be provided with overload protection.
2) If the cable is protected in a consumer unit, it would normally be classed as a circuit.
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www.voltimum.co.uk/consult.php?universe=consult.index.questions