Sharing neutrals

infinity said:
I love MWBC's, for homeruns all the way back to the panel they were a no brainer but once the simultaneous disconnect rule entered the code they pretty much disappeared. IMO a 2-wire circuit is less dangerous but if we were still allowed to use MWBC's with just single pole breakers I would continue to use them.
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infinity said:
I love MWBC's, for homeruns all the way back to the panel they were a no brainer but once the simultaneous disconnect rule entered the code they pretty much disappeared. IMO a 2-wire circuit is less dangerous but if we were still allowed to use MWBC's with just single pole breakers I would continue to use them.
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One thing I like to always mention that is often not thought about: in my experience, when people do use mwbcs they use a three-pole breaker. Three single pole breakers with a handle tie are significantly less expensive.
 
But to be clear you can't "share" neutrals unless it is a MWBC. If you have multiple 2 wire circuits in a JB and you add something to a circuit you have to get the hot and neutral from the same circuit, not the hot from 1 circuit and the neutral from another circuit.
 
Eddie702 said:
But to be clear you can't "share" neutrals unless it is a MWBC. If you have multiple 2 wire circuits in a JB and you add something to a circuit you have to get the hot and neutral from the same circuit, not the hot from 1 circuit and the neutral from another circuit.
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That’s obvious, and when Sherry neutrals, you must identify the ungrounded conductors that go with that neutral via cable, tie, or tape something that joins them together, identifying that they are, indeed, multiple circuits, sharing a neutral
 
infinity said:
Correct. We use numbers tags on the conductors.
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That is usually where I find the errors.

Other than amp clamping the neutrals and moving through the breakers, is there a easier way to double check the tags are right?

Would you include that tagging in outlet boxes where splices exist? The code section 200.4(B) says enclosures. So like only panelboards or is there another section that I am missing?
 
Elect117 said:
That is usually where I find the errors.

Other than amp clamping the neutrals and moving through the breakers, is there a easier way to double check the tags are right?

Would you include that tagging in outlet boxes where splices exist? The code section 200.4(B) says enclosures. So like only panelboards or is there another section that I am missing?
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Something like this might be handy for that application:

rack-a-tiers.com

Pulse Tracer - Rack-A-Tiers Since 1995

SEE IT, HEAR IT, TRACE IT! The Pulse Tracer is an audible and visual circuit identifier. Plug it in, and instantly create a visual and audible pulse. The Pulse Tracer allows a clamp meter to pick up the variance in current at the panel for easy circuit identification. <strong>Please note: The...
rack-a-tiers.com rack-a-tiers.com
 
Elect117 said:
Would you include that tagging in outlet boxes where splices exist?
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Only if there was a MWBC or several neutrals in the same raceway entering the box.

Elect117 said:
That is usually where I find the errors.
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Not sure why there would errors but I guess that it's possible. I've never seen anyone check neutrals unless they were troubleshooting a problem.
 
Eddie702 said:
If you have multiple 2 wire circuits in a JB and you add something to a circuit you have to get the hot and neutral from the same circuit, not the hot from 1 circuit and the neutral from another circuit.
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That is not a MWBC. What is described there is just plain not safe. Even what was once common just tying all the "whites" together in the box with multiple circuits entering the box, Not Good and has lead to shocks. Not sure it was ever compliant.
Gotten nailed with one such set up in a hidden j-box changing a light on a "dead" circuit and someone turn on the light in another room that was from a different circuit but all the neutrals were tied together.
 
electrofelon said:
Something like this might be handy for that application:

rack-a-tiers.com

Pulse Tracer - Rack-A-Tiers Since 1995

SEE IT, HEAR IT, TRACE IT! The Pulse Tracer is an audible and visual circuit identifier. Plug it in, and instantly create a visual and audible pulse. The Pulse Tracer allows a clamp meter to pick up the variance in current at the panel for easy circuit identification. <strong>Please note: The...
rack-a-tiers.com rack-a-tiers.com
Click to expand...

Thanks.

infinity said:
Not sure why there would errors but I guess that it's possible. I've never seen anyone check neutrals unless they were troubleshooting a problem.
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It has happened when the contractor was installing new lighting and receptacle circuits. They forgot to label, mark, or identify the neutral that belonged to the MWBC. For example, one instance had plans called for regular branch circuits on a 120/208V board. The number of neutrals and single pole breakers didn't add up so I asked which ones needed handle ties. They didn't know. So we went through and verified the neutrals that belonged to the MWBCs. By going through the branch circuit breakers and amp clamping one neutral at a time we were able to identify the neutrals that belonged to the MWBCs and the contractor was able to put on the cable ties. As we identified the breaker position we put numbered stickers on each neutral. So if it was a MWBC it had two numbers corresponding to the breaker position.
 
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