I have two unused 220V, 20-amp circuits (#12) in my garage. It would be very difficult to pull a new wire to the garage from the breaker-box on opposite side of house. Can I put the two 20-amp circuits on a double two-pole quad breaker in the breaker box and by properly combining the circuits in the garage have a single 220V 40-amp circuit?
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Combining Circuit
- Thread starter lar7777
- Start date
sberry
Banned
What is it you want to run?
sberry
Banned
I wired up to an old uf wire to a garage. It was old, but it was sturdy and hooked it to a gfci circuit before it left the main. I labeled it gfci and no equipment ground. I was contemplating the number of reasons for the label. It wont protect short circuit from other source.
Useless for surge suppression. In the case of the detatched garage no ground rod either. Not sure how much is to be gained in old wood bld with a rod. It now is fed from 12 vs old 14 with a 30 on it.
Useless for surge suppression. In the case of the detatched garage no ground rod either. Not sure how much is to be gained in old wood bld with a rod. It now is fed from 12 vs old 14 with a 30 on it.
wyliesdiesels
Well-known member
No that wouldnt work.
A 40a circuit would be fed by a double pole 40a breaker not dual 20a breakers
A 40a circuit would be fed by a double pole 40a breaker not dual 20a breakers
I understand one cannot run unprotected parallel wire because of unequal current sharing, etc., but in this case each wire is protected by its own circuit breaker, so unequal sharing should not be an issue. I guess the point is these are not really parallel wires since there is individual breakers between each wire and the supply; wouldn't paralleled wires be two wires connected together to a single ?
wyliesdiesels
Well-known member
Yeah paralleled conductors would be fed from the same breaker pole.
teamextreme
Well-known member
wylies and bert both provided the correct answer. Paralleling conductors is done all the time to provide ampacity equal to the total cross sectional area of both conductors, however, it's only done on larger wires because as Bert pointed out, it's a code violation below 1/0. Technically speaking, there's no reason this wouldn't work, but for some reason NEC doesn't like it. As wylies said, both conductors would land on one pole of the breaker.
Terry D
Well-known member
Also the thing about paralleling conductors is that they need to be pretty close to the same length. so the current divides equally.
sberry
Banned
I was trying to reason my way thru this. It would leave a set or overload in the event of a failure with 1 leg right, would leave 1 set not properly thermal protected , it's probably within short circuit rating even with double the breaker,,, not thermal in the event of a problem? Ground fault is going to be split, maybe not with the set of conductor that faulted?
Big conductors are not part of cables but likely from same pipe/source with same grounding means?
Big conductors are not part of cables but likely from same pipe/source with same grounding means?
Last edited:
wyliesdiesels
Well-known member
What the OP may not understand is he wont be getting a 40a circuit. Just 2 20a circuits.
If this is a detached garage, then its already a code violation.
If this is a detached garage, then its already a code violation.