How Many


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Old 11-14-07, 02:01 PM
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How Many

How many 120Vac circuits can I run with a single nutral.

in other words how many 25 amp circuit breakers can I run with a single white wire? all 12 awg "hot wires" white is 10 awg.
 
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Old 11-14-07, 02:29 PM
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You may run no (zero) 25 amp circuits on 12 gage wire.

If you made a mistake and meant to ask about 20 amp circuits then the answer would be two 20 amp circuits may share a neutral, as long as all the wire is 12 gage copper (or larger), provided the hot wires come from opposite legs of the incoming 240 volt service.
 
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Old 11-14-07, 04:32 PM
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For the single phase system typically duex [ two ] as long you have both hots on oppiste legs and with #12 wire NM it always 20 amp max.

this is common on resdential useage
but for commercal three phase the answer will be differnt but will not disscussed in here because majorty of the electrical related is single phase here.

for 25 amp you have to use the #10 wires no but if or whatever.

I dont know where you got the 25 amp figures for #12 wires but that number is kinda out of the scope for most useage but have specal useage to go higher but right now it is not related to this forum because the code compated matter so IMO it best just follow the common figures per NEC / CEC codes.

Merci, Marc
 
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Old 11-14-07, 05:54 PM
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my guess is that he got it from the NEC since #12 wire is rated at 25 amps (60ºC and 75ºC).

What he has failed to do is understand the requirement of the NEC to use no large than a 20 amp breaker on #12 wire (unless you get into the exceptions Marc spoke of).

That is one of the many problems with people using the code whithout a real understanding of the complexities and seemingly counter instructive sections of the code.

That is why those here that use it regularly try to help where we can but trust me, there are times that even the best electricians I have met have problems with figuring out what is actually right and wrong per the NEC. It is a difficult and confusing set of rules and to top it off, they change parts of it every 3 years.
 
 

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