AFCI required on MWBC?

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kwired said:
New loophole to get out of using AFCI's - only run MWBC's, and claim they are not "120 volt circuits" :cool:
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That would be a great loophole, except you wouldn't be able to install any 15A or 20A, 125V receptacles on the circuit, so the loophole is self defeating.
 
david said:
If a 20 amp small appliance multi wire branch circuit is not two branch circuits than thousands of kitchens have been wired in violation and passed inspection by thousands of inspectors for 50 plus years
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The beauty of 210.4(A) is that it gives us a choice. If we run a single MWBC for the small appliance branch circuits, and we want to consider it as two 120V circuits for compliance with 210.11(C)(1), great. Then the two circuits will need to comply with 210.12.

But if you buy the idea that an MWBC considered as a single 120/240 circuit does not need to comply with 210.12, all that means is that to avoid needing to AFCI the small appliance branch circuits, you'd need to run two MWBCs for them.

No contradiction between the proposed interpretation and past practice.

Cheers, Wayne
 
david luchini said:
That would be a great loophole, except you wouldn't be able to install any 15A or 20A, 125V receptacles on the circuit, so the loophole is self defeating.
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Sorry, where is the prohibition on installing a 125V receptacle on a 120/240V branch circuit? If there is one, I agree it would sink this line of thought.

Cheers, Wayne
 
jaggedben said:
I've got jap saying all the AHJs agree with him. Others saying AFCIs required.
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Jap never said anything about AFCI's not being required on a MWBC.

Only that a branch circuit is not a MWBC if it's strictly 120 volts.

JAP>
 
Are handle ties mandatory for multiple 1p breakers feeding a MWBC , or, just a requirement for all to have a means to be simultaneously disconnected ?


Jap>
 
david luchini said:
406.4(A)
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UL RTRT guideinfo says in part "Duplex receptacles rated 15 and 20 A that are provided with break-off tabs may have those tabs removed so that the two receptacles may be wired in a multi-wire branch circuit or multiple branch circuits."

So a duplex receptacle seems to be rated for the "voltage class" 120/240.

Cheers, Wayne
 
jap said:
Jap never said anything about AFCI's not being required on a MWBC.

Only that a branch circuit is not a MWBC if it's strictly 120 volts.

JAP>
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Actually, you quite clear said the converse: an MWBC is not a 120-volt circuit. Which in the context of my question would definitely mean that the arc fault requirement doesn't apply. But it seems you have never convinced an AHJ of that? Please clarify the record on that point, your responses now seem contradictory. :blink:


jap said:
Are handle ties mandatory for multiple 1p breakers feeding a MWBC , or, just a requirement for all to have a means to be simultaneously disconnected ?
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Not a means 'to be simultaneously disconnected'. A means 'that will simultaneously disconnect.' May seem subtle, but it means that simultaneity cannot be dependent on the user. Practically speaking, it means handle ties are required.
 
wwhitney said:
UL RTRT guideinfo says in part "Duplex receptacles rated 15 and 20 A that are provided with break-off tabs may have those tabs removed so that the two receptacles may be wired in a multi-wire branch circuit or multiple branch circuits."

So a duplex receptacle seems to be rated for the "voltage class" 120/240.

Cheers, Wayne
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I don't see anything in that text that says that the receptacle is rated for the "voltage class" 120/240.

In addition, 406.3(A) says that the receptacle shall be listed and marked with the manufacturer's name or identification and voltage and ampere ratings. If he voltage rating marked on the receptacle is 125V, then it is not rated for 120/240V. If the mwbc is not a 120V circuit, as the loophole argument says, then 406.4(A) would prevent a 125V rated receptacle from being installed on it.
 
jaggedben said:
Actually, you quite clear said the converse: an MWBC is not a 120-volt circuit. Which in the context of my question would definitely mean that the arc fault requirement doesn't apply. But it seems you have never convinced an AHJ of that? Please clarify the record on that point, your responses now seem contradictory. :blink:




Not a means 'to be simultaneously disconnected'. A means 'that will simultaneously disconnect.' May seem subtle, but it means that simultaneity cannot be dependent on the user. Practically speaking, it means handle ties are required.
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AFCI requirement was never part of my statement.

Only that a MWBC is not a 120v circuit,or that a 120v circuit is not a MWBC. The circuit would have to have more than only 1 120v circuit to be a MWBC, otherwise there would not be one. K-wire Picked up on it when he stated 120/240v 120/208v or 277/480v. We do a lot of reading between the line where we're from.

as far as the "To be simultaneously" or "That will simultaneously" disconnected, is going to require some type of "User" somewhere somehow to do either of them.

They aren't going to magically disconnect themselves now are they?

Jap>
 
jap said:
AFCI requirement was never part of my statement.

Only that a MWBC is not a 120v circuit,or that a 120v circuit is not a MWBC. The circuit would have to have more than only 1 120v circuit to be a MWBC, otherwise there would not be one. K-wire Picked up on it when he stated 120/240v 120/208v or 277/480v. We do a lot of reading between the line where we're from.
And here I initially thought you were trying to give me a useful answer to my question. :roll::slaphead:

as far as the "To be simultaneously" or "That will simultaneously" disconnected, is going to require some type of "User" somewhere somehow to do either of them.

They aren't going to magically disconnect themselves now are they?

Jap>
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I don't really want to go down this irrelevant tangent, but the point is that you cannot say that two separate breakers allow the user to simultaneously disconnect. The installation has to be such that they 'will' simultaneously disconnect when the user operates one or the other to do so.
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oldsparky52 said:
IMO, you are wrong.
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How can a strictly 120v circuit be a Multi Wire Branch Circuit when a strictly 120v circuit only requires 2 conductors?

If you do not have more than 2 conductors, then, there is no way possible you're dealing with a Multiwire Branch Circuit which is 2 ungrounded conductors that share a neutral.

JAP>
 
jaggedben said:
jap said:
AFCI requirement was never part of my statement.

Only that a MWBC is not a 120v circuit,or that a 120v circuit is not a MWBC. The circuit would have to have more than only 1 120v circuit to be a MWBC, otherwise there would not be one. K-wire Picked up on it when he stated 120/240v 120/208v or 277/480v. We do a lot of reading between the line where we're from.
And here I initially thought you were trying to give me a useful answer to my question. :roll::slaphead:



I don't really want to go down this irrelevant tangent, but the point is that you cannot say that two separate breakers allow the user to simultaneously disconnect. The installation has to be such that they 'will' simultaneously disconnect when the user operates one or the other to do so.
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And I dont really want to break the bad news to you that if the handle tie is actually not a requirement, then I could use 2 1p shunt trip breakers on whatever 2 opposing phases I want with a remote pushbutton and be good to go.

JAP>
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oldsparky52 said:
IMO, you are wrong.
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Meter Readings without the EGC considered on a 12/3 NM cable.

Black Conductor #1 to Neutral = 120v = 120v circuit= No MWBC
Red Conductor #2 to Neutral = 120v = 120v circuit = No MWBC
Black Conductor #1 to Red Conductor #2 = 0 volts = Installer screwed up and shared a neutral with 2 like phases = No MWBC

Black Conductor #1 to Red Conductor #2 = 240v, Black Conductor #1 to Neutral = 120v, Red Conductor #2 to Neutral = 120v = MWBC.

Summary: A 120v circuit may be PART of a MWBC, but, is not a MWBC in and of itself.

JAP>
 
This thread is asking if AFCI protection is required for MWBC's. Your argument about someone wiring a three wire cable incorrectly is like a dog chasing it's tail.
 
infinity said:
This thread is asking if AFCI protection is required for MWBC's. Your argument about someone wiring a three wire cable incorrectly is like a dog chasing it's tail.
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The question the OP asked is:

Is a multi-wire branch circuit a '120-volt' circuit?


I guess we'll just let him believe that it is.


JAP>
 
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