Wire color on electrical circuit from transformer through a disconnect

[controlsdude]

I'm working on an industrial design where I have a single phase 480VAC to 120VAC transformer, fed from a circuit breaker in a panel. The feed goes from this panel, to the transformer. The secondary of the transformer, single phase 120VAC, goes into a different enclosure which has a disconnect on it.

I know that per Code, we cannot disconnect a Neutral conductor. So the 120VAC wire on the bottom of the disconnect would be Red. But... the Neutral wire... Is it OK to be just white, or does it need to be white with orange? Technically, it still has a live connection to a device, namely the secondary of the transformer, and I would not consider it "safe".

If you need some more info let me know. I feel like we do this circuit all the time, but for some reason, it stuck in my mind this time lol.

 

[zbang]

Assuming this is NEC territory and not UL508/other code which might be different-

It's really just like any other step-down transformer, which becomes an SDS. The neutral does have a connection to the secondary but it also needs to be bonded to the grounding system, which makes it as safe as any other neutral. And it follows the same color requirements as a grounded conductor (in 200.6).

 

[Jraef]

If your "Neutral" is grounded at the transformer it is not "live" per se, it is no different than any other grounded conductor. White insulation (article 200.6), unless you are running it in the same raceway, cable, box etc. as other neutrals derived elsewhere. If you are mixing that neutral into something that has another neutral, then you would have to add a stripe. From what you described, you are not.

 

[LarryFine]

What they said: once you ground it, it won't be hot. It's white because that indicates that it IS a grounded conductor.

It can seem scary to ground a wire coming out of a transformer, but it's no different than any other grounded system.

It can be as simple as a green wire between the new neutral bus in the disconnect and the nearest electrode terminal.