Twin Circuit Breakers?

Merry Christmas
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What I was "fishing" for is the possibility of overheating the neutral due to too much current draw. That is why I was also saying the grounded conductor can be oversized, reducing the heat - not reducing the current.

It is similar to an earlier thread about multiple grounded/neutral conductors being replaced by using one larger grounded/neutral conductor.
 
Pierre C Belarge said:
What I was "fishing" for is the possibility of overheating the neutral due to too much current draw. That is why I was also saying the grounded conductor can be oversized, reducing the heat - not reducing the current.

It is similar to an earlier thread about multiple grounded/neutral conductors being replaced by using one larger grounded/neutral conductor.
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that was basically what I was trying to convey with my Christmas light story...
 
You certainly can use tandems and MWBC's as long as you do it correctly. For example, two tandem breakers in adjacent spaces supplying two 3-condcutor NM's: as long as both blacks land on one tandem's two terminals and the two reds on the other tandem's terminals, you have proper MWBC's.
 
The sort of 'common neutral' circuit that Pierre is describing is _explicitly_ permitted for outside branch circuits, and not _prohibited_ for interior branch circuits.

-Jon
 
The problem we are discussing is a true and common fire hazzard. when untrained people sometimes twin a mwbc they use the same phase conductor with a common neutral which becomes an additive current. 20 amp twin on A phase you will have 40 amps coming back on a 12 wire with no ocp on it(neutral). The proper way to twin a breaker with a 3 wire is to utilize different phases like A/B phase which cancel each other. 20-20=0 amps on neutral. I see this mixed up all the time in the field.
 
Somehow most of the guys allready hit the nail on the head with this situation and myself i get few service call like that and it was spooky allight due very poor planning with the grounded conductors.

one box i did see but unforetally i should took a photo of it [ shame on me :mad: ] half of all the grounded conductors were burnted due too many duplexes and not even set up right due this breaker box did warn not to use duplex breakers at all and it was packed pretty good.

it have 60 hot conductors in 40 space box [ it was rated to take 40 full spacers only ]and have to back tracked to see how far it went it was a bit of damaged and suprised it did not get the place on fire yet.

the curpit was a **growls ** one of the worst DIY i ever see for a while.

Merci,Marc
 
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