multiple homeruns for neutral only?

Question

I work in conduit and run single wires. I have a weird one.

I have an always-hot (black) and neutral (white) pair that run from the panel passing through A to serve loads at B and C.

At C, always-hot (black) continues to a switch loop at D. The switched-hot (blue) comes back through C, B and A to go down another branch, AA, to serve the lamp.

The neutral for the lamp (white) goes from AA through A back to the service panel.

The circuit has 2 neutrals (white), one serving the receptacle loads at B and C, and the other serving the lamp load at AA. They pass like ships in the night at A, not connecting, and run alongside in the same conduit from A to the panel.

Edit: Here is a drawing. I added a second circuit (red/gray) that is unrelated, simply to illustrate that boxes B and C have a lot of other stuff going on.

Is it kosher for the circuit (black) to have two neutrals on the neutral bar?

Answer 1

Here is the deal:

No matter how you wire things, you normally need to have two wires. One with the outgoing current and one with the return current. Otherwise you will get inductive heating of any ferrous materials.

If you split a neutral (return the outgoing current back to the source in a separate conduit) you will get inductive heating.

So, to answer your question, the neutral at point A may or may not be joined. This is a fielder's choice since all of the current leaving the panel on the black wire is returning on the two neutrals so the net current (algebraic sum of the current) in the conduit from the panel to point A is zero. However, it is bad technique to have more than one neutral return to the panel per phase conductor. It could be confusing to a future electrician.

This is the key: The algebraic sum of current at any point in the system must add to zero to avoid inductive heating.

Good luck and stay safe!

Answer 2

I am not sure I am reading your question properly.

No, if the entire circuit does not run grouped throughout the length of the circuit. NEC Article 300.3 (B).

Yes if all you are saying is that the neutral does not go from load A to a switch in D.

It's important to identified each neutral For B and C, and the neutral for A if they are two different neutrals and not connect them together.

Sidebar: A neutral serving more than one circuit, the overcurrent device must be interlocked. NEC 210.4 (B).

Answer 3

I think as long as you pig tail the netuals in the panel as to function as one neutral and tape the pass thrus together in the junction box then should be kosher.