Section 210.4B

[fvetere]

What section in the NEC permits sharing a neutral on 120V multi circuit outlets. or does each circuit need its own neutral wire?
For example..Ckt 1. 3. 5 have the same neutral?

Per section 210.4B they are telling me to us a simultaneous disconnect of all ungrounded conductors at the point where the branch circuit originates - i.e a 3-pole breaker would be required.

 

[david luchini]

What section in the NEC permits sharing a neutral on 120V multi circuit outlets. or does each circuit need its own neutral wire?
For example..Ckt 1. 3. 5 have the same neutral?

See 210.4(A)

Per section 210.4B they are telling me to us a simultaneous disconnect of all ungrounded conductors at the point where the branch circuit originates - i.e a 3-pole breaker would be required.

A 3-pole breaker is not required, though it would be acceptable. Three single-pole breakers with a common handle tie would also be acceptable.

 

[cowboyjwc]

Also don't forget about 210.4(D). Can't believe that after all this time how often I call those two sections.

 

[Coelec]

See 210.4(A)



A 3-pole breaker is not required, though it would be acceptable. Three single-pole breakers with a common handle tie would also be acceptable.

If dedicated neutrals were used for each hot, would this eliminate the need for common handle ties of multi-pole breakers.......?

 

[Smart $]

If dedicated neutrals were used for each hot, would this eliminate the need for common handle ties of multi-pole breakers.......?

Yes.

 

[tom baker]

If dedicated neutrals were used for each hot, would this eliminate the need for common handle ties of multi-pole breakers.......?

Yes because you no longer have a MWBC, and the dedicated neutral is really a grounded conductor.

 

[Coelec]

Yes because you no longer have a MWBC, and the dedicated neutral is really a grounded conductor.

Thanks tom baker and smart $
now I now why. :thumbsup:

 

[Aleman]

Another question regarding this section

Another question regarding this section

Just when I thought I had a handle on this issue :blink:

I posted with several questions on the New guy with questions thread. One of the questions regarded this same subject, sharing neutrals. It came up when I was installing GFI's in a warehouse and found some overhead drops sharing a neutral between multiple hots from separate phases. I understand this can be done because of the load cancellation on the neutral so it will only carry unbalanced current. But I missed the part about the disconnects needing to be tied together. Because they are not.

So my questions here are...Is this a 'multiwire' circuit since there are 3 circuits ran into one raceway used to power several outlets? I am not clear on the definition of multiwire, unless it is any branch circuit with more than 1 current carrying conductor.

And do I need to tie these breakers together to make this installation code compliant?

I can see if they were tied together it would ensure that the hots would be of different phases. Maybe that's the purpose of this rule?

In article 210.7 the word 'yoke' is used in describing multiple branch circuits. Can someone clarify that for me? I didn't see it defined in the front of the book.

 

[Smart $]

...Is this a 'multiwire' circuit since there are 3 circuits ran into one raceway used to power several outlets? I am not clear on the definition of multiwire, unless it is any branch circuit with more than 1 current carrying conductor.

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.

And do I need to tie these breakers together to make this installation code compliant?

If they were installed before the handle tie requirement (2008 NEC?), no.

I can see if they were tied together it would ensure that the hots would be of different phases. Maybe that's the purpose of this rule?

It would, but not the reason. The reason is to disconnect all ungrounded conductors of the mwbc when you are working on only one branch, just in case you disconnect the neutral you will not be subjecting the remainder of the circuit to a floating neutral point.

In article 210.7 the word 'yoke' is used in describing multiple branch circuits. Can someone clarify that for me? I didn't see it defined in the front of the book.

Yoke is the metal mounting strap to which typical receptacles, for example, are assembled around.

 

[AllCircuitsElectrical]

it appears to me this is a 3 phase setup .. 4 wire setup ...hence 1,3,5 .... IMHO ... and the breaker would be fine ....but i may be reading too much into it ..:lol:

1 and 5 could not share the same nuetral ... no matter what the disconnect .... if it was not a 3 phase setup

 

[Aleman]

If they were installed before the handle tie requirement (2008 NEC?), no.



It would, but not the reason. The reason is to disconnect all ungrounded conductors of the mwbc when you are working on only one branch, just in case you disconnect the neutral you will not be subjecting the remainder of the circuit to a floating neutral point.


Yoke is the metal mounting strap to which typical receptacles, for example, are assembled around.

Thanks for clearing things up. This is almost certainly pre 2008, it's an old warehouse we leased.

 

[Smart $]

Thanks for clearing things up. This is almost certainly pre 2008, it's an old warehouse we leased.

Oh! I forgot to mention that disconnecting a neutral while working on one branch could also subject you to live voltage on one side.

 

[Aleman]

Oh! I forgot to mention that disconnecting a neutral while working on one branch could also subject you to live voltage on one side.

That would hurt!

 

[realolman]

If dedicated neutrals were used for each hot, would this eliminate the need for common handle ties of multi-pole breakers.......?

Yes.

Don't you need them on 220 v circuits, or three phase?

 

[Smart $]

Don't you need them on 220 v circuits, or three phase?

Yes, but then they wouldn't be mwbc's... :?

 

[ActionDave]

Don't you need them on 220 v circuits, or three phase?

Not always.

240.15 (B)
Circuit breakers shall open all ungrounded conductors of the circuit
both manually and automatically unless otherwise permitted
in 240.15(B)(1), (B)(2), (B)(3), and (B)(4).

(2) Grounded Single-Phase Alternating-Current Cir-
cuits. In grounded systems, individual single-pole circuit
breakers rated 120/240 volts ac, with identified handle ties,
shall be permitted as the protection for each ungrounded
conductor for line-to-line connected loads for single-phase
circuits.

(3) 3-Phase and 2-Phase Systems. For line-to-line loads
in 4-wire, 3-phase systems or 5-wire, 2-phase systems, indi-
vidual single-pole circuit breakers rated 120/240 volts ac
with identified handle ties shall be permitted as the protec-
tion for each ungrounded conductor, if the systems have a
grounded neutral point and the voltage to ground does not
exceed 120 volts.

 

[Smart $]

Not always.

Really???

(3) 3-Phase and 2-Phase Systems. For line-to-line loads
in 4-wire, 3-phase systems or 5-wire, 2-phase systems, indi-
vidual single-pole circuit breakers rated 120/240 volts ac
with identified handle ties shall be permitted as the protec-
tion for each ungrounded conductor, if the systems have a
grounded neutral point and the voltage to ground does not
exceed 120 volts.

 

[ActionDave]

I thought he was talking about three pole breakers instead of handle ties.

 

[Smart $]

I thought he was talking about three pole breakers instead of handle ties.

That sorta got jumbled in there. Suffice it to say, line-to-line-load breakers must have handle ties (among other requirements) if they are not multi-pole breakers.