MWBC

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mstrlucky74

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NJ
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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Strathead

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Ocala, Florida, USA
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Electrician/Estimator/Project Manager/Superintendent
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.
 

roger

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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
 

Strathead

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Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
It would probably have to be 1,3,5 or 2,4,6 and yes MWBC's are single circuits.

Roger

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.
 

mstrlucky74

Senior Member
Location
NJ
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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Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
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
 

Little Bill

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Tennessee NEC:2017
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Semi-Retired Electrician
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:
 

infinity

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New Jersey
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Journeyman Electrician
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

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.
 

roger

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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?
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
 

mstrlucky74

Senior Member
Location
NJ
If an Engineer specifies separate neutrals then you best throw the word "MWBC" out the window and run the neutrals!:happyyes:

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....???
 

Little Bill

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Location
Tennessee NEC:2017
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Semi-Retired Electrician
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....???

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.
 

MAC702

Senior Member
Location
Clark County, NV
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.

If you use a handle-tie, can you just remove it during the work?
 
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