MWBC

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mstrlucky74

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So I was listening to Mike Holt video and he said a multi wire branch circuit is considered one circuit her article 100. So if I have circuit 1 2 and 3 connected as a multi wire branch circuit that's technically one circuit? Thank you

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mstrlucky74 said:
So I was listening to Mike Holt video and he said a multi wire branch circuit is considered one circuit her article 100. So if I have circuit 1 2 and 3 connected as a multi wire branch circuit that's technically one circuit? Thank you

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In a normal scheme that is circuits 1,3,5 but I can see where it could be considered one circuit or three. I am not sure it is a "fact" per the code.
 
It would probably have to be 1,3,5 or 2,4,6 and yes MWBC's are single circuits. MWBC's are permitted to be considered multiple circuits, see 210.4(A)

Roger
 
roger said:
It would probably have to be 1,3,5 or 2,4,6 and yes MWBC's are single circuits.

Roger
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As I indicated I am not knowledgeable about the nuance, but did you consider them a single circuit when breaker ties weren't required and you could have circuits 1,4,30 sharing a neutral? I see it more as semantics than a hard definition.
 
So if the engineer specifies separate neutrals for branch circuits could you run multi wire Branch circuits and either have a handle tie or multi pole breaker and still satisfy his requirement? Per code it's okay but you're really not running separate neutrals as requested by the engineer. So I'm not sure what to think.

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mstrlucky74 said:
So if the engineer specifies separate neutrals for branch circuits could you run multi wire Branch circuits and either have a handle tie or multi pole breaker and still satisfy his requirement? Per code it's okay but you're really not running separate neutrals as requested by the engineer. So I'm not sure what to think.

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no
 
mstrlucky74 said:
So if the engineer specifies separate neutrals for branch circuits could you run multi wire Branch circuits and either have a handle tie or multi pole breaker and still satisfy his requirement? Per code it's okay but you're really not running separate neutrals as requested by the engineer. So I'm not sure what to think.

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If an Engineer specifies separate neutrals then you best throw the word "MWBC" out the window and run the neutrals!:happyyes:
 
mstrlucky74 said:
So I was listening to Mike Holt video and he said a multi wire branch circuit is considered one circuit her article 100. So if I have circuit 1 2 and 3 connected as a multi wire branch circuit that's technically one circuit? Thank you
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It can be but for most installations it is not a single circuit which is the reason you use a MWBC in the first place.
 
Strathead said:
but did you consider them a single circuit when breaker ties weren't required and you could have circuits 1,4,30 sharing a neutral?
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Generally speaking I looked at them as multiple circuits because that's what we were needing but, looking at the properties of the circuit they are single circuits regardless of the breaker location. It would be better to think of it as phases A, B,and C.

Roger
 
Little Bill said:
If an Engineer specifies separate neutrals then you best throw the word "MWBC" out the window and run the neutrals!:happyyes:
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Got it. isnt this a complete waster of money. Wouldn't a MWBC with simultaneous disconnecting means( handle ties or multi pole breaker) offer the same safe guard against open neutral/loaded neutral etc....???
 
mstrlucky74 said:
Got it. isnt this a complete waster of money. Wouldn't a MWBC with simultaneous disconnecting means( handle ties or multi pole breaker) offer the same safe guard against open neutral/loaded neutral etc....???
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It used to be a time/money saver until the handle tie/multi-pole breaker rule was introduced. Now it is inconvenient if you just need to work on one of the circuits but have to turn off all the circuits. A busy plant or office wouldn't want half their equipment down just to work on one circuit.
 
Little Bill said:
It used to be a time/money saver until the handle tie/multi-pole breaker rule was introduced. Now it is inconvenient if you just need to work on one of the circuits but have to turn off all the circuits. A busy plant or office wouldn't want half their equipment down just to work on one circuit.
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If you use a handle-tie, can you just remove it during the work?
 
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