Sub panel wiring

[Darren]

Weird wiring-

A sub panel is located directly under the main panel. The branch circuit wiring runs thru the main panel into the sub panel. However, the grounds and neutrals of the sub panel circuits are terminated in the main panel.

I'm pretty sure this is wrong but need some confirmation.

Thanks

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[Marc]

Neutrals and hot wires should terminate within the same enclosure, because once they separate, the magnetism generated by their currents no longer cancel out. Magnetism generates electric currents in conductors which eventually ends up as heat.

I don't make a big deal of it except that it illuminates the ineptitude of the speedy petey. [:-taped]

Marc

[Speedy Petey]

NEC 300.3(B) applies here:

(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 (B)(4).

[John Kogel]

I imagine the best reason for the rule would be to avoid an accidental disconnection of a neutral or grounding wire. The connections should all be visible when you take one cover off.

[Jack Davenport]

The issue would not be with the panel and its subpanel. The issue would be the short nipple between the two.

Article 300.3 does not cover the wiring in the panels. It covers

the wiring methods - as in the raceways & cables used for wiring.There is no harmonics issue in that nipple as the feeder neutral will take care of that

[Jim Katen]

The issue would not be with the panel and its subpanel. The issue would be the short nipple between the two.

Article 300.3 does not cover the wiring in the panels. It covers

the wiring methods - as in the raceways & cables used for wiring.There is no harmonics issue in that nipple as the feeder neutral will take care of that

Not the neutral. It's doing nothing. It might as well not be there. But the ungrounded feeder wires will take care of it. Power comes in through them and goes right back out through the same nipple in the branch wiring.

[Marc]

Jack is right except that it could be any combination of the 3 feeder conductors (grounded or ungrounded) that counter the magnetics of the branch circuit conductors, depending on the load distribution between those branch circuits.

The answer is the same regardless of whether harmonics of the 60 Hz are present or not.

Just my opinion...since I was wrong before, I could be wrong again.

Marc