Breaker Box Wiring


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Old 10-28-08, 09:16 PM
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Breaker Box Wiring

I understand that it is acceptable to place two circuits on one breaker (assuming the load is within limits) by pig-tailing as opposed to placing two cables under the breaker terminal. However, can the same thing (pig-tailing) be done with the neutrals or grounds, when the buss bar is full and a new circuit is being added? It seems to me that to do so would require that the pig-tail be a greater gauge than the two wires to which it is connected.
 
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Old 10-29-08, 07:50 AM
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You can only combine certain circuits on one breaker. Some examples of circuits you can't combine are kitchen, bath or dedicated appliances.

Neutrals have to be terminated one-per-screw in the panel box, they can't be combined at all. Grounds can usually be installed in pairs as long as they are the same gauge: two #12s or two #14s can go under one screw.

You can also buy an add-on ground bar which mounts to the back of the panel box to relocate some ground wires so you can free up room for neutrals.
 
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Old 10-30-08, 07:27 PM
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I think the OP is asking if neutrals can be pigtailed and the single pigtail placed under one neutral-bus screw.

I would say... no. The pigtail is a shared neutral; if both circuits are on the same leg, the neutral-conductor current could be twice the current on each hot. If the circuits are on opposite legs, then no problem, but how are you going to ensure that?

Opinions?
 
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Old 10-30-08, 07:53 PM
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I understand that it is acceptable to place two circuits on one breaker
If you place them on one breaker, then it is, by definition, one circuit, not two.

However, can the same thing (pig-tailing) be done with the neutrals
No (at least not in general), and here's why. When you combine two hot wires on the same breaker, the breaker is still protecting all those wires, so there's no issue as long as the pigtail is of sufficient size for the breaker. But when you combine two neutral wires, there isn't one breaker protecting that pigtail. There are two breakers protecting it, and thus they aren't really protecting it at all, and the wire can overheat (unless the wire is good for the current represented by the sum of the breakers). Of course if the two breakers are on opposite bus bars, it would still be okay, but I wouldn't count on that because it might not always be true in the future if changes are made.
 
 

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