I have a 2 pole 20 amp breaker that I though went straight to my washing machine in the garage, but upon tripping it I see my fridge and a couple 20 amp 120v outlets in the kitchen go out too. I am wondering if it is possible that someone has wired one side of the breaker to go to the kitchen and one side to my washing machine. If so, what would be the best way to tell? Thanks
I have one of these that I picked up at Lowe's/Home Depot:
Open up the panel and remove one wire from the breaker, then see what gets turned on. Most likely you are correct, that the kitchen outlets and fridge are on one wire, and the washer is on the other, as that would have been the Nec legal way to do it.
should they be ganged? That thought the only time breakers were ganged together was to control 240v devices.
Is the use of such a ganged (two pole) breaker for two separate circuits an acceptable practice? Just curious as to why someone would do this beside the fact it is easier to pull the wire?
A two pole breaker is now required in the 2008 code on multiwire circuits. I think in Canada it has been required for some time.
Not sure why it would matter? On some double breakers you can take the connecting bar off. If not then you would have to open the panel and disconnect one of the wires from the breaker. Turn the beaker back on and map out the circuit. Then change to the other wire....
It's possible that you have an 'Edison' circuit where one neutral wire (white) is shared by the 2 circuits. If the breaker is connected to one
12/3 cable w/red, black, white + GND then that is the case. If so then it must remain as is unless you rewire things. If not an 'Edison' circuit then there is no reason to use the double breaker and you could either remove the connecting bar or swap out the double with 2 single 20's. (Verify that the wire is 12ga or larger)Kevin
how is it a multiwire circuit? just curious.
Could you please define a "multiwire circuit?" Is it a circuit consisting of two hot wires, such as a 220 volt one where two 110 volt are used?
For single phase AC, a "multiwire circuit" is a 3 conductor (plus EGC) circuit in which there is a neutral and two hots on opposite legs. Also called an Edison circuit or a shared neutral circuit.
Yours, Wayne
As John and Wayne explained, these are circuits that share a common neutral. There was only a requirement to use a double pole breaker if both circuits were attached to devices in a single box, but it really is a much safer way to wire them, and as John pointed out is required by the 2008 NEC
I think he may be trying to determine if the washer is indeed on a separate circuit, or could it be attached to the fridge, or kitchen outlets
There are a few ways to tell. Open the front panel and see if the leads from each breaker go to a single cable or conduit. Then at the first outlet see if one hot is connected there and if the neutral is bridged where it and the other hot go to the next outlet.
Having the breakers ganged together provides additional safety. If only one circuit is off there is a possibility that the accompanying neutral wire is carrying current from the other circuit.
Thanks to both of you for the explanations. I have another question however:
If the gauge of the wire is appropriate for say 20 amps, and you supply each wire designated for line from a separate 20A breaker, how can the neutral wire be of adequate gauge for both circuits? In other words, if
20 amps were drawn on each of the line wires and the common neutral was used for both circuits, wouldn't the capacity of the neutral be exceeded and be over 20 amps?? Maybe I am missing something?
That is one of the wonders of electricity. The neutral will only carry the difference between the two phases. The hots must be on opposite phases.
The current wave cancels out. So if you have say 6 amps draw on 1 wire and 7 amps on the other, then the combined current on the neutral would be only 1 amp. 20A and 20A = 0A etc... So the most amps the neutral will see is 20A. Thats why it's important to keep the 2 wires on opposite hot legs in the panel. Using a double breaker assures that. If both hots are put on the same leg then the neutral will be overloaded.
Kevin
I knew I had to be overlooking something. Thanks.
Lets trim this christmas tree. Delete some old text.
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