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cmh · Joined: 01 Jul 2005 Posts: 1 Location: Canada

Greetings all. Quick electrical question for you. We have a split receptacle installed in our basement. The two plugs (both 120v) are split with a shared neutral, connecting back to two 15 amp single pole breakers side by side in our loadcentre.

When we bought the house the top half of that receptacle did not work. I traced the problem to a junction box where the red wires were (unsafely) separated. I reconnected the wires thereby re-enabling power to the top of the receptacle.

Now the dryer (13 amps on the faceplate) tripped its side of the circuit 45 minutes into a 60 minute drying cycle, when I was running a dehumidifier (7.4 amps on the faceplate) on the other hot.

It is my understanding that the top half of my split receptacle should have no impact whatsoever on the bottom half of the receptacle. I can't understand, then, why it should matter that the top half of the receptacle has been reconnected, causing the bottom half of the circuit to trip its breaker.

We have only lived here a few weeks and only used the dryer a few times, so it is possible that the tripping of the dryer circuit is unrelated... but it seems like a strange coincidence when it blew 30 minutes after I fixed the top circuit.

For now I've switched off the breaker to the top half, figuring that if I don't understand this I could have done something stupid.

So, two questions:

1. Is my understanding of the shared neutral correct?
2. How can I stop my dryer from tripping its breaker?

b · Posted: Sun Jul 03, 2005 1:59 am Post subject:

The nuetral wire carries the imbalance of the load... that is why different phases can share a nuetral... I am not convinced that is what is going on in your installation. If what you have is a piggyback kind of breaker then it is the same phase. (You don't want to put 2 phases on a regular receptacle anyway bc it will have a 220V potential and would be dangerous.) If you were running the dryer at 13A and a humidifier at 7.4A... then your circuit breaker did its job as you would be pulling 20A on a 15A circuit. The wire is most likely 14awg and only rated for 15A. There was probably a reason the wire was disconnected in the junction box. I would advise to disconnect and safely cap off wire in jb. Your dryer at 13A is all you should have on that circuit. If you really need another plug at that location run new wire with its own nuetral and ground... if you are unsure be safe and call an electrician.
B