MWBC with line-neutral AND line-line loads

rszimm

Member
Can I put both line-neutral AND line-line loads on a single MWBC. Got a home shop that needs 120V and 240V receptacles throughout. Some of the equipment (e.g. band saws, table saws) runs on 240. Some runs off 120. Generally no two pieces of equipment will be on at the same time. Thinking about putting a single MWBC to power it. 2017 NEC. 210.4.C says "MWBC shall supply only line-neutral loads", but exception 2 says "When all ungrounded conductors of the MWBC are opened simultaneously by the branch-circuit overcurrent device". Given that 210.4.B already requires that all ungrounded conductors be simultaneously disconnected, isn't 210.4.C completely moot/irrelevant?
 

david luchini

Moderator
Staff member
Given that 210.4.B already requires that all ungrounded conductors be simultaneously disconnected, isn't 210.4.C completely moot/irrelevant?
Being "disconnected" and being "opened simultaneously by the branch OCD" are different things, so 210.4(C) isn't moot.

Two or three single pole circuit breakers with a handle tie would accomplish the first but not the second.

A two pole or three pole circuit breaker would accomplish both.

Edit: Or what Sierra said
 

rszimm

Member
Of course. Great point. OK, so is there anything else in the code that I'm not thinking of that would prevent a mixture of line-line and line-neutral loads on the same MWBC?
 

dkidd

Senior Member
210.4(C) Line-to-Neutral Loads. Multiwire branch circuits
shall supply only line-to-neutral loads.
 

jap

Senior Member
Of course. Great point. OK, so is there anything else in the code that I'm not thinking of that would prevent a mixture of line-line and line-neutral loads on the same MWBC?
A mixture of line-line and line -neutral loads occur all the time.

Think of Range or Dryer circuits for example, or, even a 120/240v panel in itself.

Just be careful what you call the circuit and be mindful of the OCPD installed ahead of the conductors.


JAP>
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Why do you say that? It would seem Exception 2 applies here.
Read the exception again. Only line-to-neutral loads unless protected by a breaker that assures simultaneous opening of all lines.
 

Cow

Senior Member
I would do everything in my power to talk them into a subpanel, rather than hooking a bunch of 120v and 240v receps to the same circuit.
 

ptonsparky

Senior Member
I would do everything in my power to talk them into a subpanel, rather than hooking a bunch of 120v and 240v receps to the same circuit.
What will it add for a 4 circuit main lug panel? Maybe $100? Not worth the time thinking about it.
 

jap

Senior Member
There may not be the need to add subpanel.

The OP was simply asking if he could do it.

Heck, for all we know the panel may already be in the garage.

JAP>
 

kwired

Electron manager
There may not be the need to add subpanel.

The OP was simply asking if he could do it.

Heck, for all we know the panel may already be in the garage.

JAP>
Exactly, say this is an existing detached garage with just a MWBC supplying it, I'd probably do what OP is asking if the chance of too much load at once isn't very great.
 
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