Multiple branch neutrals tied together

[Jon456]

This is something I see alot in old work: in a junction box where multiple branch circuits are present, often all the neutrals are tied together under one wire nut. I think it's hazardous because after disconnecting the power on one branch, you could still have current flowing back on the accompanying neutral. The things guys will do to save a few wire nuts.

I also see all the grounds tied together too. While I don't think this is hazardous, I'd like to know if this is preferred or shunned.

 

[infinity]

This is something I see alot in old work: in a junction box where multiple branch circuits are present, often all the neutrals are tied together under one wire nut. I think it's hazardous because after disconnecting the power on one branch, you could still have current flowing back on the accompanying neutral. The things guys will do to save a few wire nuts.

IMO this has less to do with wire-nuts and more to do with incompetence.

 

[jumper]

This is something I see alot in old work: in a junction box where multiple branch circuits are present, often all the neutrals are tied together under one wire nut. I think it's hazardous because after disconnecting the power on one branch, you could still have current flowing back on the accompanying neutral. The things guys will do to save a few wire nuts..

Are you talking about a MWBC?

I also see all the grounds tied together too.

All grounding wires are supposed to be tied together 250.148

 

[Jon456]

Are you talking about a MWBC?

No, definitely not talking about a MWBC. The example I came across today consisted of three branch circuits (two 120VAC circuits and one 240VAC circuit) passing through an 8"x8" junction box mounted on the exterior of the house. One 120VAC circuit originated in the main breaker panel, the 240VAC circuit originated in a sub-sub-panel (Main -> Sub A -> Sub B), and the other 120VAC circuit originated in a sub-sub-sub-panel (Main -> Sub A -> Sub B -> Sub C).

Sub-B is a nightmare.

 

[Dennis Alwon]

If the neuuutrals from different circuits are tied together and they are not a part of a mwbc then you have a violation and you will get unwanted EMF's. This install becomes a parallel connection of the neutrals.

 

[Jon456]

All grounding wires are supposed to be tied together 250.148

Thanks for the code citation. I knew the box needed to be grounded, I just wasn't sure if grounds from different circuits were all supposed to be tied together. The fact that the circuits were coming from different subpanels is what jumbled my marbles.

Of course this would be a problem if it were two branches from separate subpanels connected by a 3-wire feeder, but since that's only allowed for a detached building, hopefully the branches would never both see the inside of the same junction box. In any case, that was not what I was dealing with today.

 

[jxofaltrds]

When I first started that is what all the electricians I worked with were doing.
I told them that this was wrong. But what did I know I was just a 'helper'.
Its wrong, against code and not safe.

 

[Dennis Alwon]

Remember Jumper (Derek) is talking about the grounding conductor and not the grounded conductors(Neutrals). The grounding conductors must be tied together but the grounded conductors must be separated from different circuits.

 

[Jon456]

Remember Jumper (Derek) is talking about the grounding conductor and not the grounded conductors(Neutrals). The grounding conductors must be tied together but the grounded conductors must be separated from different circuits.

Yup, I understood the distinction.

 

[LarryFine]

If the grounded conductors are connected together, they're effectively paralleled, which is a no-no.