Sharing Neutrals

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scot120

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In article 210.4 , it talks about Multi-wire Branch Circuits . I am trying to figure out the requirements to share a neutral . Back in the old days it was a common practice .
210.4 ( b ) says the ungrounded conductors need to be disconnected simultaneously . ( d ) describes how the grounded and non-grounded conductors should be grouped and marked .

1 . Does 210.4 B and D have to be applied or either one ?


2. Would a lighting contactor for both conductors be considered a simultaneous means of disconnect , in order to share a neutral ?
 
If you read those sections closely then IMO neither of those requirements (B) or (D) apply to a lighting contactor.
 
scot120 said:
I have a 3 c w/G going from a lighting contactor to a junction box , which feeds just lights . Can I share a neutral in the multi-conductor cable , for lights as per 2008 code change ?
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As described, you don't say anything about the wiring from the branch circuit overcurrent device (fuse or circuit breaker). What is the lighting contactor supply side wiring?
 
Their is a raceway from the panal to the lighting contactor , with single pole breakers .Individual neutrals can be added to the contactor . Their is a 3c #6 w/G out of the contactor into a splice box in a tank farm . Could I group and tag the wires to share the neutral as per 210.4 ( D ) or consider the contactor as a means of simultaneously disconect both hots per 210.4 ( B )?
 
scot120 said:
Their is a raceway from the panal to the lighting contactor , with single pole breakers .Individual neutrals can be added to the contactor . Their is a 3c #6 w/G out of the contactor into a splice box in a tank farm . Could I group and tag the wires to share the neutral as per 210.4 ( D ) or consider the contactor as a means of simultaneously disconect both hots per 210.4 ( B )?
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If the circuit from the panel to the lighting contactor uses a shared neutral, the breaker(s) at the panel which supply that feeder have to disconnect together. This does NOT mean that they need a common trip, although that would be OK. They do need at least a handle tie.

Now if you run separate neutrals out to the contactor, I do not think that you will be allowed to originate a new Multi Wire Branch Circuit (MWBC) at that point.

So if you intend to share neutrals from the contactor the luminaires and you are not installing individual OCPDs at the input or output of the contactors to create branch circuits starting at that point, then you have to share neutrals all the way back to the panel and the tied breakers.
 
I agree with Gold and will just add that contactors are controllers not disconnecting means. They cannot be used as an NEC required disconnect.
 
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