ECN Forum Forums General Topics of the Trade General Discussion Area 3-Phase colors

I went to a house a couple of weeks ago to investigate problems with an extended light & ceiling fan circuit. I found that the previous "electrician" apparently only had one type of wire - a single cable (i.e. for onduiit use) in red.

Apart from single cables draped everywhere across the attic, it was fun trying to work out which reds were hot and which were neutral. He'd even used red for grounds, noth that it mattered much, because he'd carefully linked the fan and accessory boxes together, but not actually connected any of this wiring to a ground!

I only went there for a 20 minute job.....

Sparky,
A SDS has nothing to do with creating a neutral. You can have SDS systems without neutrals. A SDS is a power source that does not share a circuit conductor with any other power source. A transformer is a SDS because there is no physical connection between the primary and secondary circuit conductors. An autotransformer is not a SDS because there is a conductor common to both the primary and secondary side of the transformer.
Don(resqcapt19)

Another color code question that's just occurred to me:

When you run a single-phase 120V branch from a single-pole C/B at a 120/208 3-phase panel, do you always use black for the hot or do you match it with the appropriate phase color? (Im talking conduit systems; I assume if the 120V branch were Romex it would pretty much have to be black.)

How about a single-phase 277V branch run from a 277/480V panel? Brown & gray? Matched to the brown, yellow, orange (or purple!) phase?

When we run a 1-ph. 240V branch from a 3-ph. 240/415V panel, the hot is always red, even if the breaker is on the yellow or blue phase.

>do you ... use black for the hot
Yes. Color matters only when all three phases are being used.

In a way, it would be pointless to try to match these up by color since the breaker might move tomorrow when the load is redistributed and the color would be wrong.

I figured that probably was the case (like here), but it just crossed my mind that you might do it the other way.

So what about 1-ph 277V from a 277/480 panel? Brown & gray, or back to plain old black for the hot?

I just wondered if any of the other Canadians caught the phasing of a 3 phase 120/208 volt system? In Canada we use:
Phase A-Red
Phase B-Black
Phase C-Blue
Sorry just though there'd ever be a difference between us and the US because so much of our equipment is American made.