MWBC

[mstrlucky74]

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]

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]

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]

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]

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]

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

 

[sameguy]

No

 

[Little Bill]

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]

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.

 

[MAC702]

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 what if he asks for it to be run in "conduit?" :lol:

 

[LarryFine]

. . . you could have circuits 1,4,30 sharing a neutral?

Well, you wouldn't want that, as it would put 1 and 4 on the same phase.

 

[infinity]

Well, you wouldn't want that, as it would put 1 and 4 on the same phase.

1 and 4?

 

[roger]

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

 

[LarryFine]

1 and 4?

Nope - I miscounted.

 

[mstrlucky74]

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]

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]

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?

 

[ptonsparky]

1 and 4?

Drives me nuts but some start at top left 1,2,3,4...

 

[LarryFine]

Drives me nuts but some start at top left 1,2,3,4...

Which is exactly what my mind did. Bad mind!