Orange, blue, and gray are not standard residential wire colors in the US. If you follow the National Electric Code (NEC), the gray would be a neutral, and the orange and blue would be "hot". There is no ground in this combination, since grounds must either be green or bare copper. The black/white/copper group are standard house wiring (hot/neutral/ground), and probably connect to the switch as you surmise. I'd need to understand what the orange/blue/gray are connected to in order to be of much help. My best guess is that they were installed by someone who was not familiar with the NEC standards. I would recommend that you have an electrician replace the non-standard set of wires.

So from the NM cable(the wires coated in plastic sheathing), the black was connected to the black from the fan, the white was connected to the white of the fan and the bare copper ground was connected to the green of the fan or the fan body?

What leads of the fan were the orange, blue and gray connected to?

You're going to have to find a manual for the fan. Almost certainly these wires control some ancillary function (light separate from fan or heater or such).

I didn't explain well. The only wires coming from the old fan were white and black. The orange, blue and grey are house wires within conduit. There are also another set of house wires (black, white, copper) within the plastic sheathing that were connected to the old fan. The old fan was strictly a fan, no heat or light. From where the sheathing coated wires come up from I think they must be from the wall switch in the bathroom. It's an old bathroom that our builder installed the fan in when we had an addition put on 4 years ago. I think kurto is right that our builder just didn't use NEC standards when he ran the wiring (maybe he was colorblind...ha). I still don't understand why there is the extra set of wires (in the sheathing) that come from the wall switch, unless it was a shortcut of some type because he was contending with the old wiring. thanks!

In your last sentence of your first post your infer that a simple situation would of been black to black, white to white and ground to ground. So seems that what you were anticipating when you began removing the fan.
But you also state while actually removing the fan, "It had three wires within conduit connected to it, those wires were orange, blue and grey. Then also connected to it was a separate set of wires coated in plastic, they were black, white, and a copper ground."

Sounds like someone was trying to do a quick job during a commercial break or a halftime show maybe??

Anyway you say the orange, blue and grey wires from withing the conduit were definitely wired to the fan terminals? Or could they have been wire-nutted to the black and white wires from the NM cable? Then a pigtail from the wirenuts to the fan?

Are the wires from within the conduit solid or stranded.

Go CHIEFS

jaysgarden, I think my brain was the one taking the commercial break not to have paid closer attention when disconnecting the old fan (I don't know much, but I know better than that). Anyhow, you interpreted my convoluted explanation perfectly. And, yes I believe all three sets of wires (NM cable,conduit, and fan) were pigtailed then wire-nutted. Finally, yes the conduit wire is solid not stranded. thanks.

Message deleted.

This post was edited by bppark on Sat, Jan 4, 14 at 11:31

Better to start a new thread than to piggyback onto one that is three years old with the replies possibly going to that original person.
Does your attic have sidewalls at a gable end? Does your bath have an outside wall?

Oops--I thought I was starting a new thread. I've been away from this site for a while and my mouse forgot where to click. I'm trying to delete this message to start over, but it's not working!