Super Neutral Question

[GerryB]

Is there or was there a code section allowing a "super neutral" to replace for example individual neutrals in a panel. I came across a panel recently that had been relocated to the front of the building. There was a ridgid conduit run from the old panel ie: j-box to the new. The hots were brought through to the breakers and the neutrals were all spliced to a #6 and that was the only neutral brought through. I did post about this before and thought there was a reply about the super neutral. Also I was thinking about gen-tran panels that only bring one neutral and ground back to the main panel. In that case I think a non-ferrous nipple makes it OK. Thanks in advance.

 

[petersonra]

I believe this is no longer permitted.

 

[jumper]

2011 NEC.

200.4 Neutral Conductors. Neutral conductors shall not
be used for more than one branch circuit, for more than one
multiwire branch circuit, or for more than one set of ungrounded
feeder conductors unless specifically permitted
elsewhere in this Code.

 

[dicklaxt]

Gerry,I'm confused can you draw me a better picture?

dick

 

[97catintenn]

I think he means that were the old panel was, he put all the neutrals on a bus bar and then ran one heavy neutral to the new panel.

I mean, he is just asking about it.

 

[dicklaxt]

I think he means that were the old panel was, he put all the neutrals on a bus bar and then ran one heavy neutral to the new panel.

I mean, he is just asking about it.

If thats the case and that looks to be so,,,,,,,you are right, an accident waiting to happen.

dick

 

[GerryB]

If thats the case and that looks to be so,,,,,,,you are right, an accident waiting to happen.

dick

It was worse than that. About 30 feet of conduit. The neutrals, about eight of them were all twisted together under a blue scotchlock. I was working in this residence/funeral parlor and had to add a circuit. I entered my cable into the panel and was working a few minutes before I even noticed it. I was wondering since it didn't look that old, (newer 200 amp), if the inspector maybe didn't take the cover off the panel. Like I said I know on the gen-tran transfer panels they only carry one neutral and one ground from the main panel into their tranfer panel, but this was 30 feet away.

 

[infinity]

This is still permitted under Article 225 {225.7(B)} which would limit the practice to wiring outside of the building.

 

[ceb58]

2011 NEC.

200.4 Neutral Conductors. Neutral conductors shall not
be used for more than one branch circuit, for more than one
multiwire branch circuit, or for more than one set of ungrounded
feeder conductors unless specifically permitted
elsewhere in this Code.

Also 300.3 (B)

(B) Conductors of the Same Circuit.​

​

​

​

​

All conductors ofthe same circuit and, where used, the grounded conductorand all equipment grounding conductors and bonding conductorsshall be contained within the same raceway, auxiliarygutter, cable tray, cablebus assembly, trench, cable, orcord, unless otherwise permitted in accordance with​

300.3(B)(1) through (B)(4).

 

[kwired]

Is there or was there a code section allowing a "super neutral" to replace for example individual neutrals in a panel. I came across a panel recently that had been relocated to the front of the building. There was a ridgid conduit run from the old panel ie: j-box to the new. The hots were brought through to the breakers and the neutrals were all spliced to a #6 and that was the only neutral brought through. I did post about this before and thought there was a reply about the super neutral. Also I was thinking about gen-tran panels that only bring one neutral and ground back to the main panel. In that case I think a non-ferrous nipple makes it OK. Thanks in advance.

As far as your concerns and use of a non ferrous nipple - as long as all conductors of the circuit(s) are within the nipple, you still have a net that cancels itself and no magnetic effects on the nipple.

If thats the case and that looks to be so,,,,,,,you are right, an accident waiting to happen.

dick

Why is there any more accident waiting to happen than if a service or feeder neutral should fail?

The biggest issue here (outside of code violations) is that to work on this neutral in any way that may open it you have to turn off every circuit involved. I kind of sort of still have no problem with that but that is not what the NEC wants so it is what it is. It is likely a little difficult to calculate what maximum current on that neutral will be for the purpose of determining what size conductor to use.

 

[texie]

In addition to the "super" neutral violation, you have to wonder if derating for number of conductors was a consideration.

 

[ActionDave]

In addition to the "super" neutral violation, you have to wonder if derating for number of conductors was a consideration.

No worries if multi-wire branch circuits are used.
Your simply replacing a lot of little neutrals with one big one. Either way neither would count for derating

 

[texie]

No worries if multi-wire branch circuits are used.
Your simply replacing a lot of little neutrals with one big one. Either way neither would count for derating

I wasn't thinking of the neutral(s), rather the potential of having 30-40 ungrounded conductors in one conduit needing derating.

 

[ActionDave]

Ahhh. :slaphead: My mind didn't go near any other conductors but the neutral.