2 sources of Power in same conduit ?

[Isaiah]

Can 277V circuits and 120V circuits from two different sources (and serving two different loads) be ran in the same conduit?


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[ActionDave]

Yes. The neutrals have to be different colors. Traditionally grey is used for 277V and white for 120V.

 

[infinity]

I agree with Dave done all of the time. There was a time several code cycles ago a requirement for the neutral of one of the systems to have a stripe. Simple white and gray colored neutral conductors weren't enough.

 

[tank728]

I agree with Dave done all of the time. There was a time several code cycles ago a requirement for the neutral of one of the systems to have a stripe. Simple white and gray colored neutral conductors weren't enough.

Does your company do this often?

 

[infinity]

Does your company do this often?

Depends on the particulars of a job but we typically run both voltages in raceways when there is both 120 volt and 277 volt lighting fed from a lighting control panel.

 

[brantmacga]

They can, but there is a code section that requires you to label the j-boxes with each circuit number and source notifying anyone else that you have two different sources present. I can’t think of the code #.


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[letgomywago]

They can, but there is a code section that requires you to label the j-boxes with each circuit number and source notifying anyone else that you have two different sources present. I can’t think of the code #.


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I thought that label was only if there was a circuit ran through another panel. I'd like to know the code if that's a requirement for junction boxes though?

 

[jaggedben]

They can, but there is a code section that requires you to label the j-boxes with each circuit number and source notifying anyone else that you have two different sources present. I can’t think of the code #.


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I'll believe it when you can tell us the section. Heard that enough times.

 

[brantmacga]

I'll believe it when you can tell us the section. Heard that enough times.

210.5(C)

I was incorrect stating you have to put the circuit # but you do have to identify the different voltages in some way, and either the box must be labeled or you have to post somewhere what your method is

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[jaggedben]

210.5(C)

I was incorrect stating you have to put the circuit # but you do have to identify the different voltages in some way, and either the box must be labeled or you have to post somewhere what your method is

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Ok.
That applies to terminations, connections, and splice points. So conductors that pass through jboxes are exempt. Boxes don't need the method posted, only panelboards or 'similar distribution equipment'.
I thought that the circuit # thing was wrong.
Also this applies to branch circuits, 215.12(C) has the same language repeated for feeders. (Why isn't this just said once somewhere, like in 110?)

Of course it's good practice to use different color wires for different voltage systems, and saves time. I think most people do that for branch circuits at the least.

 

[masterinbama]

The only "no" I can think of is legally required standby circuits

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[don_resqcapt19]

The only "no" I can think of is legally required standby circuits

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That would apply to emergency circuits, but it does not apply to legally required standby circuits.

701.10 Wiring Legally Required Standby Systems.
The legally required standby system wiring shall be permitted to occupy the same raceways, cables, boxes, and cabinets with other general wiring.

 

[lordofthisworld]

The only "no" I can think of is legally required standby circuits

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Life safety Art 700.

 

[Another C10]

Can 277V circuits and 120V circuits from two different sources (and serving two different loads) be ran in the same conduit?

I don't recall that ever being legal in california nor would I consider doing it myself , although as mentioned above many seem to accept the practice. Typically it use to be 1 single or three phase system single or multiple boat would be allowed within a conduit from the original source it was fed from, no combining various panels to one conduit. The exception was normal power and emergency power normally found with egress lighting systems.

 

[infinity]

I don't recall that ever being legal in california nor would I consider doing it myself , although as mentioned above many seem to accept the practice

Is there a local amendment in California that prohibits this?

 

[roger]

Can 277V circuits and 120V circuits from two different sources (and serving two different loads) be ran in the same conduit?


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I don't recall that ever being legal in california nor would I consider doing it myself , although as mentioned above many seem to accept the practice.

300.3(C)(1)

 

[jaggedben]

Is there a local amendment in California that prohibits this?

No.

 

[Another C10]

I get the 600v insulation concept but I truly thought mix matching voltages from other sources was a no ..no.
I doubt I'd ever do it anyway unless I'm in a sort of bind, were it made most sense. I can see its benefit with a needed nearby pull box .

Maybe it was a usual spec on a school or hospital project years back ..

 

[Another C10]

I truly thought mix matching voltages from other sources was a no ..no.

Question: wouldn't the grounds need to be kept isolated as well being that they are derived, bonded from two seperate transformers.

 

[infinity]

Question: wouldn't the grounds need to be kept isolated as well being that they are derived, bonded from two seperate transformers.

Nope. They would be required to be connected together when complying with 250.148.