277 &120V Grounds in same conduit

[let the light shine]

Recently, The roofing contractor closed the rooftop with a rubber layer. the conduit for the WP outlet wasn't installed in time so I have to come out on the wall outside to install and penetrate through the bldg to a J-box which provides 277v back to the panel. I can set a j-box ahead of the277v panel and pipe over to the 120v panel. is this ok per grounding by code or should I rely on the 277v grounding conductor?(Ibelieve that I need 2 grounds. 1 120v and 1 277v.)

 

[roger]

Re: 277 &120V Grounds in same conduit

There is nothing wrong with two EGC's in a conduit even if they are from different systems.

However, there probably is no need to add a second one, all equipment grounding (bonding) is (should be) common at some point in most circumstances.

I would just use the existing EGC if it is large enough for the branch circuit and or feeder.

Roger

[ December 12, 2004, 03:55 PM: Message edited by: roger ]

 

[don_resqcapt19]

Re: 277 &120V Grounds in same conduit

Roger,

However, there probably is no need to add a second one, all equipment grounding (bonding) is (should be) common at some point in most circumstances.

I don't think that would be in compliance with 300.3(B). You need an EGC back to each source.
Don

 

[roger]

Re: 277 &120V Grounds in same conduit

Don, the original question would infact have an EGC back to the source of both systems,

I can set a j-box ahead of the 277 v panel and pipe over to the 120v panel.

there would be an EGC for this portion of the run (atleast I asumed) and after the juction one common EGC could be a part of the 120 v circuit and the 277 v circuit or feeder. This would meet the requirement of 300.3(B).

If the installation requires a bond bushing or a box be bonded in the conduit run, and you installed an EGC for both systems, which one should be used for this bonding?

Roger

 

[don_resqcapt19]

Re: 277 &120V Grounds in same conduit

Roger,

there would be an EGC for this portion of the run (atleast I asumed) and after the juction one common EGC could be a part of the 120 v circuit and the 277 v circuit or feeder.

As long as there is a direct path back to each source, it would meet the code. You could combine the two EGCs at the roof box, run a single EGC to the panel junction box and then run separate EGCs to each panel.
Don