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| As I work my way through all the wiring changes I'm doing I've decided to add several shared neutral multi-wire branch circuits (MWBCs), e.g., replace old 12/2 and 14/2 dishwasher and disposal circuits with one 12/3 MWBC.
The online permitting process just asks how many circuits are being added or changed and asks for a description of same... so does a MWBC count as 1 or 2 new circuits? I can see it being counted as 2 circuits since electrically they are on seperate hot busses... but since I'm only stringing one set of main 12/3 wires that will be hooked to the same 2-pole breaker with one neutral and one ground I don't really see why I should pay double the price for one additional wire. Can anyone clarify what the standard practice is for MWBCs and permits? Thanks. |
Follow-Up Postings:
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- Posted by petey_racer (My Page) on Wed, Jan 6, 10 at 20:03
| I think this would be a local interpretation issue. In the eyes of the NEC it is BOTH one and two circuits depending on how you apply it. I don't think you can argue that it is two circuits as far as branch circuits go, but if it is feeding a detached structure it can and is considered one circuit. |
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- Posted by ronnatalie (My Page) on Wed, Jan 6, 10 at 22:23
| It's a local interpretation thing (the NEC doesn't say squat about permit charges). Here it's two circuits as far as the billing on the permit goes. |
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| It is a local issue with the permit department. A number of places I work count every breaker pole as a separate circuit, making every 240 V load two circuits for permit purposes. A multi-wire is the same, two breakers, two circuits for the permit. It is a revenue thing, not an NEC thing. |
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- Posted by tom_in_seattle (My Page) on Sat, Jan 9, 10 at 14:43
| Thanks for the input. I sent an email to the local Labor & Industries office that handles electrical inspections, etc. and asked the question. The response was: a MWBC counts as two circuits and a 240V circuit counts as one. This is how I originally specified the circuits to be added or modified on the permit, so it should be OK. |
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