Terminal Bars in a Junction Box

Originally Posted By: jpope
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I?ve never seen this done before. A terminal bar was added into this junction box for the EGC?s and neutrals. If this neutral bus was isolated form the enclosure, would this setup be allowed?


![](upload://5NfDni8QQwIQx7h16kclPhRARux.jpeg)

![](upload://9OLAA0FHxW2BLlwTG7aWRXYBjwb.jpeg)

I don?t see an issue with the terminal bar for the EGC?s, but what kind of problems might the neutral bar create other than the potential for possibly unbalanced loads on the neutral conductors back to the panel board?

Any NEC references (for or against) would be appreciated.


Originally Posted By: bbadger
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It’s not an enclosure containing the service disconnect so it the same violation you see all the time with sub panels.


I do use those same bars in junction boxes many times but only for the EGCs, I never would think of doing that with neutrals.

As far as code.

110.3(B) The bars are UL listed grounding equipment, not neutral bars.

The bonding of the 'neutral to ground' 250.24(A)(5)

Quote:
(5) Load-Side Grounding Connections. A grounding connection shall not be made to any grounded circuit conductor on the load side of the service disconnecting means except as otherwise permitted in this article.


There are probably a number of code sections that are being ignored but I think 250(A)(5) is the main one.

Hey, is the 'neutral bar' screwed down to the box or did they leave it floating?


--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN

Originally Posted By: jpope
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That was my question Bob. “Does the Neutral bar need to be removed or simply isolated?”


It is currently bonded (screwed down) to the enclosure.


Originally Posted By: bbadger
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I guess my first post was mostly how it violates code.


As for what it will really do?

It has IMO a small chance of causing any noticeable effects.

It could create enough imbalance to heat the metal raceways.

If you could cause enough imbalance it would be possible to make those flex conduits red hot.

At the current levels in that box it would be very doubtful.

At higher current levels strange stuff happens,

Picture a metal pipe clip supporting a PVC raceway with a severe imbalance, the clip melted through the plastic then the conductors resulting in a short circuit.

I also know where a large roof HVAC unit was wired incorrectly causing an imbalance of the full load current .

The EMT conduits suppling it got so hot that the conductors melted to the conduit.


--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN

Originally Posted By: jpope
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bbadger wrote:
110.3(B) The bars are UL listed grounding equipment, not neutral bars.


But they're used for "neutral bars" at load side equipment (subpanels), no?


Originally Posted By: bbadger
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jpope wrote:
That was my question Bob. "Does the Neutral bar need to be removed or simply isolated?"

It is currently bonded (screwed down) to the enclosure.


Unless it is only connecting neutrals of the same circuit it could be 'floated' however to do that within the listing would mean getting a terminal bar with isolating mounting means.

Simply leaving the bar floating in the air is at best cheesy, I think you you could tape it up and argue it is no different than a tapped up split bolt.

But if it is connecting different circuits neutrals together I would cite 300.3(B)

Quote:
(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (4).


As always there are some exception....none apply to that picture.

K&T would be an exception.

You can also ignore 300.3(B) if you use all NM, plastic boxes and plastic fittings.

Here is a little from the handbook.

Quote:
This general rule remains consistent with electrical theory; that is, to reduce inductive heating and to avoid increases in overall circuit impedance, all circuit conductors of an individual circuit must be grouped. Similar requirements are found in 300.5(I).



--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN

Originally Posted By: jpope
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Thanks Bob.


Originally Posted By: bbadger
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jpope wrote:
bbadger wrote:
110.3(B) The bars are UL listed grounding equipment, not neutral bars.


But they're used for "neutral bars" at load side equipment (sub panels), no?


![icon_lol.gif](upload://zEgbBCXRskkCTwEux7Bi20ZySza.gif)

Yes, kind of, in that case they are factory installed and will be directly connected to the incoming neutral terminal

We are also talking paper work mumbo jumbo.

If I ask for grounding bars I get the part shown above in a plastic bag with a sticker I am supposed to put beside it with the wire range, torque specifications etc. That sticker will also say UL listed Grounding.

If I ask for neutral bar I may well get the same bar with little plastic feet that I install with a different sticker with another listing.


--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN

Originally Posted By: Greg Fretwell
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Take a peek at the second connector on the right side. There is only a neutral and a ground in that raceway. Was the box warm? I have always wondered how much inductive heating you would really get.


Originally Posted By: jpope
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Actually Greg, It came from the distribution panel like that. I assumed those were the “main” conductors for the neutral and grounding bus.


I think this guy was trying to save time and material by just tapping the grounded conductors and equipment grounding conductors in at the junction box, and running the ungrounded conductor to the distribution panel.

FYI - I didn't remove this cover. This is how I found it.


Originally Posted By: bking
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If there are neutrals spliced in a junction box (floating bus bar or wire nut) the neutral conductor going back to the other panel must be large enough to handle all 120V loads that could be on each circuit connected.


ie. Four 120V 20amp circuits spliced into one neutral at a junction box would be ok if that neutral was 4 gauge copper.


Originally Posted By: pbolliger
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Looks like the cover could not be installed to begin with.


The first picture top right has 3 hot wires and two neutral exiting from the enclosure where the panel cover would go on.. They are not going through a fitting at all just wired around the box. At least you can find the screws for the cover.. There left in the holes.. ![icon_biggrin.gif](upload://iKNGSw3qcRIEmXySa8gItY6Gczg.gif)


Thanks for share with us. Interesting find. JPope


Originally Posted By: bbadger
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bking wrote:
If there are neutrals spliced in a junction box (floating bus bar or wire nut) the neutral conductor going back to the other panel must be large enough to handle all 120V loads that could be on each circuit connected.

ie. Four 120V 20amp circuits spliced into one neutral at a junction box would be ok if that neutral was 4 gauge copper.


That would only be acceptable if all four of the 'hots' of those circuits where in the same raceway as the one 4 AWG neutral.

Any other way and you will have inductive heating of the metal raceways.


--
Bob Badger
Electrical Construction & Maintenance
Moderator at ECN