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The house I inspected today, all the neutral wires were too short in the electrical panel. Someone had spliced three or more neutral wires together in different groups with one wire going on up to the neutral busbar.

While I assume this to be wrong, I do not know why. I know that you cannot put two neutral wires together under one screw on the neutral busbar because you cannot isolate each circuit when you work on them. Plus each screw is only rated for the one neutral wire.

Is there something that says that neutral wires cannot be tied together with only one wire going back to the busbar? (this was only a 13 year old house, looked like the original panel)

Thanks,

Jeff Euriech

Arizona Prime Property Inspection LLC

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Shared neutrals are allowed only when the circuits originate from separate poles on the bus.

The reason for this would be that the load on the nuetral would not be exceeded when both circuits were in operation because they would each be 180 degrees separate from one another. When one cycle is positive the other would be negative and vice versa. The resultant neutral load is not additive.

Your second picture clearly shows three circuit neutrals combined to one. This is not allowed and unsafe. Clearly at least two of these circuits must share the same phase.

Your first picture (yellow wire nut) would only be allowed if the two originating circuits (hots) came from opposite sides of the panel.

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For a brief period of time (1931 - 1940) the NEC allowed up to 8 branch circuits to share a common neutral, on the wishful thinking that the load would be balanced. Though the permission to do this was dropped in 1940, it didn't become specifically prohibited until the 2011 NEC, in section 200.4, which says "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."

Even prior to 2011 it would be a code violation due to the conductors lacking adequate overcurrent protection. As Bob pointed out, the currents on the neutral that makes it home to the bus could be the sum of whichever phase has a load on it. Even if they upsized the neutral it would have parallel overcurrent protection and not be allowed by 240.8.

All in all, just a fancy way of saying this is jackleg work. Why couldn't they just extend each one of these neutrals individually?

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Shared neutrals are allowed only when the circuits originate from separate poles on the bus.

I think the allowed sharing of neutrals is intended to apply to multi wired branch circuits. The arrangement listed by Jeff is not directly related to the allowance for shared neutrals as written in codes. However, I do agree that the implication of overloading the single terminated conductor is the same.

I think the arrangement listed by Jeff is more directly applicable to the termination of neutrals, not the sharing of neutrals. The following document describes further.

http://home.comcast.net/~marylandhomein ... rounds.pdf

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I think the arrangement listed by Jeff is more directly applicable to the termination of neutrals, not the sharing of neutrals. The following document describes further.

http://home.comcast.net/~marylandhomein ... rounds.pdf

Wires in a panel board always terminate (end) under a screw, either at at a breaker (non grounded conductor) or at the neutral or ground buss.

The article referenced deals strictly with termination. The neutrals in the OP do not terminate at the wire nuts. They terminate through the short single conductor that is attached to the neutral buss.

They share this conductor. Whether it is for 6 inches in the panel or 12 feet from a remote junction box, it is a shared neutral.

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I think the arrangement listed by Jeff is more directly applicable to the termination of neutrals, not the sharing of neutrals. The following document describes further.

http://home.comcast.net/~marylandhomein ... rounds.pdf

Wires in a panel board always terminate (end) under a screw, either at at a breaker (non grounded conductor) or at the neutral or ground buss.

The article referenced deals strictly with termination. The neutrals in the OP do not terminate at the wire nuts. They terminate through the short single conductor that is attached to the neutral buss.

They share this conductor. Whether it is for 6 inches in the panel or 12 feet from a remote junction box, it is a shared neutral.

Those individual neutrals do terminate. They terminate at the wire nut instead of under a terminal screw as they should.

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Nice try, John.

The article you referenced deals specifically with sticking more than one neutral under a single neutral bus screw. Assuming the screw remains tight (a false assumption, as history has shown) each neutral only carries its own load.

In a shared neutral one wire (regardless of length) carries the entire load of multiple circuits, as in the original post.

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The fact that you cannot effectively isolate those neutrals individually is a termination problem as indicated in the article I linked.

I understand that the load in the single conductor can be greater than its intended to handle. However, all "shared neutral" language in code that I'm aware of is with regard to multi wired circuits.

If you can show me otherwise, please do.

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The neutrals in the OP do not terminate at the wire nuts. They terminate through the short single conductor that is attached to the neutral buss.

I disagree. Any connection involving more than two conductors is a termination. A connection involving only two conductors isn't a termination because the current flowing in each are identical to each other.

The connection between the common neutral and the various individual neutrals is a termination. The connection of the common neutral to the bus-bar is also a termination.

Marc

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Douglas Hansen already gave you the code cite. Note that it is not the same as the one presented in the article you referenced. The reason being that they are dealing with two separate issues.

In your article it specifically draws attention to the problem created when you try to isolate circuits sharing a common connection while under load.

This problem occurs only when you try to 'service' individual circuits.

While this problem also exists for multiple neutrals that are wire nutted together the problem originally discussed dealt solely with the current carrying capacity of a shared neutral.

This problem occurs when the circuits are in normal operation (under a load).

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The neutrals in the OP do not terminate at the wire nuts. They terminate through the short single conductor that is attached to the neutral buss.

I disagree. Any connection involving more than two conductors is a termination. A connection involving only two conductors isn't a termination because the current flowing in each are identical to each other.

Marc

Why am I not surprised?

How 'bout I say "...the circuits are not terminated at the wire nut."

I think everybody else got that. We all know that the panel board provides a screw termination for every individual wire it is designed to handle.

John's premise is that the article he referenced addresses the problem in the original post. However it addresses only the service aspect of conjoined neutrals and not the operational safety problem imposed by a shared neutral.

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How 'bout I say "...the circuits are not terminated at the wire nut."

Still wrong in my opinion. Those circuits terminate at the common neutral and the common neutral terminates at the bus bar.

I'm not saying it's right. I'm reflecting on the definition of 'termination'.

Marc

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How 'bout I say "...the circuits are not terminated at the wire nut."

Still wrong in my opinion. Those circuits terminate at the common neutral and the common neutral terminates at the bus bar.

I'm not saying it's right. I'm reflecting on the definition of 'termination'.

Marc

Semantics.

'Course we could just call it a 'node' and really confuse everyone.

Your point in that context is well taken. A node is an elactrical connection from which new values of current and voltage are calculated.

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Wires in a panel board always terminate (end) under a screw, either at at a breaker (non grounded conductor) or at the neutral or ground buss.

Abandoned conductors can terminate in the panel board enclosure. They can terminate under a wire nut. So, wires in a panel board do not always terminate under a screw.

Once again, I do not disagree that the single conductor can become overloaded as Bob pointed out. I'm simply questioning the terminology of calling the condition a "shared neutral".

What if there were only two neutral conductors coming together and using a single to attach to the panel termination point? What if each of those conductors was from a different phase? In that case, there would not be potential for the single to be overloaded. However, the arrangement would still be wrong as an incorrect termination issue. It would not be an allowed "shared neutral" arrangement. The reason is, its not a "shared neutral" to begin with.

The arrangement can be called out on either or both of the potential problems discussed here. The problems caused by incorrect termination can be further explained in the document I linked.

If documentation can be provided that calling that arrangement a "shared neutral" is correct, please do so.

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A neutral being used for more than one circuit is being shared. In 3 phase systems you can have one neutral for 3 hot legs. In a single phase system like a house you would only have the two hots sharing the neutral.

If two cables were run from the panel, but were only using one breaker to supply the circuit, the neutral is not being shared. In that case the breaker panel is the same as a junction box.

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