Is it NEC code legal to have more than one conductor tied into each terminal of a circuit breaker?

6 Comments

1. An electrical engineer says:

   July 16, 2009 at 9:29 pm

   There are two points to the question. One the other answers talk about, but you specifically the two circuits are within the capacity of the breaker. That is always possible, if the two circuits are really allowed to be one circuit, then you can have one breaker.

   Your real question is can you put two wires on one terminal. In general, no terminal can have more than one wire unless specifically allowed. The Square D QO breakers generally can have two wires (both 14 or both 12 AWG, not sure about larger) for example. But if the breaker doesn’t say that is allowed, you can splice inside the panel (use a wirenut to connect your two wires to a short wire that connects to the breaker).
2. GTB says:

   July 16, 2009 at 9:29 pm

   I am not sure exactly where NEC sits on this but local code may prohibit this even if NEC says it is acceptable. I suggest you not do this.
3. btcbill says:

   July 16, 2009 at 9:29 pm

   2005NEC article 110.14(A)…"terminals for more than one conductor…shall be so identified"
4. Jim W says:

   July 16, 2009 at 9:29 pm

   Ask the AHJ since the NEC may permit it but not the local. One way or another it is not usually a good practice since the 2 conductors may not tighten equally and then work loose. It would be better to add a splice nut to the 2 and only connect one wire to the breaker.
5. Electrical Inspector says:

   July 16, 2009 at 9:29 pm

   The NEC prohibits terminating more than one conductor on any terminal that is not identified for use by more than one conductor.

   Having said that, some circuit breakers are listed for two conductors to be terminated on a single breaker (Square-D QO type is one of them). You just better have the install instructions handy when the electrical inspector looks at the panel, most don’t believe this can be done.

   My question is how do you know what the total load of the 2 circuits is? As long as you follow the manufacturer’s instructions, in some panels, this is legal.

   If both circuits are "General Lighting Circuits", and both are of the same ampacity, you can splice the conductors in the gutter space of the panel, and land one conductor on the breaker. The biggest concern would be to make sure that the 2 circuits you are doing this to are not going to be on the same leg of the panel. If they were directly above and below each other, they were on opposite legs (not phases, a house is a single phase installation). If you combine these circuits onto a single breaker, they are no longer on opposing legs, and the neutral will become overloaded. This is the danger of using a mini breaker.

   If both circuits are on opposite legs, they can share a neutral, if they are on the same leg, they cannot - unless you like fires.
6. I DID NOT HAVE says:

   July 16, 2009 at 9:29 pm

   Double tap, not allowed. Use the double breaker by replacing that existing one or wire nut to a short lead and tie in that way.