Mixing voltages

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The NEC doesn't have a problem with it if the insulation of the conductors are sufficient. Hint, what your looking for is in article 300.
 
Since the building has more than one voltage-phase system, the voltage and phase of each conductor must be indicated in a manner clearly described by signage. This distinction is usually done be means of insulation color, but could also be done with other markings at each potential splice point.
With conductors of two systems in the same conduit, it is much more likely that color will be used rather than some other marking method.
 
I used to do this quite often if I had several 277v wallpacks and several 120v outside receptacles. It didn't make much sense to run 2 conduits around the perimeter of a building if 1 would suffice. I would use a gray neutral and applicable circuit color (BR, OR, YL) for my 277v lighting circuit and I would use a white neutral with a colored stripe, depending on the lower voltage circuit color. For example, if the circuit for the recepts. was #23, I would use a white with a blue stripe for my 120v neutral. All J box covers should be legibly marked letting others know that conductors of different systems are in the boxes.
 
Rick 0920 said:
I used to do this quite often if I had several 277v wallpacks and several 120v outside receptacles. It didn't make much sense to run 2 conduits around the perimeter of a building if 1 would suffice. I would use a gray neutral and applicable circuit color (BR, OR, YL) for my 277v lighting circuit and I would use a white neutral with a colored stripe, depending on the lower voltage circuit color. For example, if the circuit for the recepts. was #23, I would use a white with a blue stripe for my 120v neutral. All J box covers should be legibly marked letting others know that conductors of different systems are in the boxes.
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White with a blue stripe could be confused as 24 VDC for controls as this is commonly seen for the 24 VDC negative, and some use Blue with a white stripe, but in the lower 48, White with a blue stripe is very common as a 24 VDC Negative, and these are definitely 2 voltages you would not want in the same conduit due to capacitive coupling.
 
I don't think anyone ever confused this as a 24v circuit, but I do see your point. I was always adamant about labeling my J boxes with voltages, circuit #'s and panel #'s
 
Rick 0920 said:
I don't think anyone ever confused this as a 24v circuit, but I do see your point. I was always adamant about labeling my J boxes with voltages, circuit #'s and panel #'s
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A man after my own heart. I do the same.
Most times I label them with a Box# which if you look on the electrical prints has a Box schedule and it tells you if its a J-Box, Pull Box, Terminal box, etc. It also gives you the circuit number, conductor info, Source and Destination, Relation ship to the wire and conduit schedule,etc.
 
Rick 0920 said:
I used to do this quite often if I had several 277v wallpacks and several 120v outside receptacles. It didn't make much sense to run 2 conduits around the perimeter of a building if 1 would suffice. I would use a gray neutral and applicable circuit color (BR, OR, YL) for my 277v lighting circuit and I would use a white neutral with a colored stripe, depending on the lower voltage circuit color. For example, if the circuit for the recepts. was #23, I would use a white with a blue stripe for my 120v neutral. All J box covers should be legibly marked letting others know that conductors of different systems are in the boxes.
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Shouldn't the identification scheme tell you there is different systems in there? Going with most popular scheme, if you open it and see black white orange and gray conductors in there then you must have a 120 volt and a 277 volt circuit in there.
 
kwired said:
Shouldn't the identification scheme tell you there is different systems in there? Going with most popular scheme, if you open it and see black white orange and gray conductors in there then you must have a 120 volt and a 277 volt circuit in there.
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Yes. That should be enough for qualified persons. But it's still acceptable to use gray as a grounded conductor for 120v circuits and white as a grounded conductor for 277v circuits. I just used the white with stripes because I thought it was a better practice and provided more identification for those that worked behind me.
 
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