# Is this allowed (or was it ever allowed)?



## brodgers (Aug 5, 2007)

Recently I came across a situation where I found 2 20-amp MWBCs pulled from the panel in a conduit (4-#12 hots) that shared a single #8 neutral. Then in a junction box the 2 MWBCs go in opposite directions and 2-#12 neutrals are spliced with the #8 neutral from the panel.

Is this or was this ever allowed under the NEC? Technically the single #8 neutral can handle the current from the 2 MWBCs. Other than missing handle ties I confirmed that 2 of the hots are on the A phase and 2 of the hots are on the B phase.


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## Jack Legg (Mar 12, 2014)

Shockdoc used to do that


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## RePhase277 (Feb 5, 2008)

I believe this was compliant at one time. It may have been only for festoon lighting. Not 100% sure though. I'll look into my old code books tomorrow morning. Maybe it will be answered by then.


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## telsa (May 22, 2015)

You're a residential electrician.

#8... explain that.

Are you from Chicago ?


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## brodgers (Aug 5, 2007)

Not from Chicago. Worked in a residence Friday where everything in the basement was ran with pipe for whatever reason. The only NM-B I saw was above the panel that came down from the first floor.

#8 = 8 gauge copper THHN.



telsa said:


> You're a residential electrician.
> 
> #8... explain that.
> 
> Are you from Chicago ?


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## MechanicalDVR (Dec 29, 2007)

I've seen that before in buildings built in the 60s!


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## hardworkingstiff (Jan 22, 2007)

I think I remember seeing it in an example in the handbook some decades ago. Using a #8 neutral like you explained. I'm pretty sure it was compliant at one time.


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## MechanicalDVR (Dec 29, 2007)

hardworkingstiff said:


> I think I remember seeing it in an example in the handbook some decades ago. Using a #8 neutral like you explained. I'm pretty sure it was compliant at one time.


But so was using asbestos insulation and you see how that ended up!


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## frenchelectrican (Mar 15, 2007)

RePhase277 said:


> I believe this was compliant at one time. It may have been only for festoon lighting. Not 100% sure though. I'll look into my old code books tomorrow morning. Maybe it will be answered by then.


It was legal in old days and it was kinda semi common to do that when they ran the junction box above the old style load centre.

Ya festoon lighting is one of them. 

Ditto with some parking lot lumaires done simauir fashion. 

I did look up in old 1984 NEC code book and seems it kinda not really mention too much at all but I am aware the older editions did allow that time so pretty much legit in that era.


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## active1 (Dec 29, 2009)

The term was Super Neutral.

Not common. But as far as I can tell and remember legal until 2011 NEC.
Before that into the 1990's there was no 200.4.
The advantage would be number of conductors in a raceway.
The weakness would be the splice method from the super to all the smaller neutrals.
If landed on an insulated neutral bar in a can, what could go wrong.
A blue wire nut could get ugly. Especially if each circuit branches off a few different ways from that super neutral box. 

2011 200.4 (New text added) Neutral conductors shall not be used for more than 1 branch circuit, or more than 1 mulitwire branch circuit, or more than 1 set of ungrounded feeder conductors unless specifically otherwise in the code.

2014 The above text was changed to 200.4(A), with (B) added (requirements of identifying the neutrals).

Multiwire circuits in the code is just like gun control.
Just keep taking away your right to share the white.
A few years from now electricians will be asking why there is only 1 neutral for 2 or 3 hots on a branch circuit.


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## brodgers (Aug 5, 2007)

Thank you for the help! I typically don't do much conduit beyond sleeving NM-B down basement walls. Coming across the "super neutral" threw me. I left alone the splice between the smaller neutrals and the super neutral.

The use of a super neutral make sense...it's a shame it has been removed. Just like other things being done in the code to protect the unqualified hacks.


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## emtnut (Mar 1, 2015)

brodgers said:


> Thank you for the help! I typically don't do much conduit beyond sleeving NM-B down basement walls. Coming across the "super neutral" threw me. I left alone the splice between the smaller neutrals and the super neutral.
> 
> The use of a super neutral make sense...it's a shame it has been removed. Just like other things being done in the code to protect the unqualified hacks.


There's a circuit that will never have an AFCI :001_unsure:


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## RePhase277 (Feb 5, 2008)

emtnut said:


> There's a circuit that will never have an AFCI :001_unsure:


Why is that a bad thing?


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## emtnut (Mar 1, 2015)

RePhase277 said:


> Why is that a bad thing?


Because it would be 100% safer with AFCIs :tt2:


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## RePhase277 (Feb 5, 2008)

emtnut said:


> Because it would be 100% safer with AFCIs :tt2:


Oh yeah. I forgot.


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## MechanicalDVR (Dec 29, 2007)

emtnut said:


> Because it would be 100% safer with AFCIs :tt2:


I thought that safety factor only applied to exterior main disconnects?


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