Multiwire Branch Circuit

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czarstoo

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This seems like an easy question, so I hope there is an easy answer. Are the circuits that are used to typically provide 240 V power to residential ranges, hot water heaters, dryers, pool pumps, etc considered to be multiwire branch circuits? The NEC definition of MWBC seems to indicate the answer is yes!
 
Re: Multiwire Branch Circuit

Only if you bring an grounded (neutral) conductor along with the ungrounded conductors.

Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
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Re: Multiwire Branch Circuit

Understand! Therefore, circuits to ranges and dryers that require and insulated neutral are MWBC and 240 V hot water heaters and pool pumps that do not require a neutral are not MWBC. correct??
 
Re: Multiwire Branch Circuit

OK! Now, what do you call the circuits that provide power to older ranges and dryers that utilize the 3 conductor connections where the neutral and ground currents both flow on the uninsulated conductor?
 
Re: Multiwire Branch Circuit

It's still a MWBC without a seperate EGC.

Roger
 
Re: Multiwire Branch Circuit

However, a 3-wire 3-phase branch circuit that uses 3 hot wires and no neutral is somehow NOT a multiwire branch circuit of at least the definitions for 2-wire and multiwire branch circuits do not include 3 wire 3 phase branches.
 
Re: Multiwire Branch Circuit

Originally posted by mc5w:
However, a 3-wire 3-phase branch circuit that uses 3 hot wires and no neutral is somehow NOT a multiwire branch circuit of at least the definitions for 2-wire and multiwire branch circuits do not include 3 wire 3 phase branches.
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Yes, it does. :)
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
Click to expand...
 
Re: Multiwire Branch Circuit

George, a MWBC has to have a grounded conductor (neutral) as part of the circuit.

Note the wording "and a grounded conductor".

I'm still not sure of what mc5w actually said in that post though. :D

Roger
 
Re: Multiwire Branch Circuit

Would a 3 phase branch circuit from a 3 wire delta system be a MWBC by definition?
 
Re: Multiwire Branch Circuit

Originally posted by infinity:
Would a 3 phase branch circuit from a 3 wire delta system be a MWBC by definition?
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No.

Edit: Well, the more I think about it, I guess it could be :D

[ May 12, 2005, 09:12 AM: Message edited by: ryan_618 ]
 
Re: Multiwire Branch Circuit

Sorry I left out a corner grounded 3 wire delta.
 
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