correcting mwbc's


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Old 02-23-14, 11:39 AM
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correcting mwbc's

I have the following circuits sharing neutrals
furnace/living room
kitchen/dining room
dishwasher/sump pump
bedroom a/ bedroom b

Do you think having an electrician out to pull a separate neutral for each circuit is a major undertaking? Something that would be treated as service call or like a rewire job?

The one I see as most critical is the furnace/living room. As a problem in the living room would take out heat in the house.
 
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Old 02-23-14, 12:38 PM
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Unless you have conduit you can't just pull a separate neutral. By code hot and neutral must be in the same raceway (conduit or sheath).
 
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Old 02-23-14, 01:45 PM
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we got conduit up here in these parts Ray.
 
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Old 02-23-14, 04:43 PM
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Do you think having an electrician out to pull a separate neutral for each circuit is a major undertaking?
Why would you even consider doing that?
 
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Old 02-24-14, 05:10 AM
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The one for the furnace/living room comes to mind. I have an electrician needing to put double pole breakers on these shared circuits. If there happened to be a problem on the living room side of that mwbc, that means a double pole breaker will take out the furnace too. Possibly leaving me without heat until a problem could be corrected.


Is that good thinking?
 
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Old 02-24-14, 06:36 AM
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The one for the furnace/living room comes to mind. I have an electrician needing to put double pole breakers on these shared circuits. If there happened to be a problem on the living room side of that mwbc, that means a double pole breaker will take out the furnace too. Possibly leaving me without heat until a problem could be corrected.

Is that good thinking?
I understand your thinking, but there is a better solution. The NEC requires a common disconnect of the two breakers in a MWBC, but the NEC does not require a common trip like you would get with a 2-pole breaker. Keep the two single pole breakers and simply install a handle tie between them to satisfy the code requirement. Now, if the living room circuit trips, it will not turn the furnace circuit breaker off. If you manually turn off either circuit, they will both turn off together. This meets the intent of the code. That being said, using a 2-pole breaker also satisfies the intent of the code, but the handle tie solution would be preferred.
 
 

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