Two Circuits In Single Conduit? - Electrical - DIY Chatroom Home Improvement Forum

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Old 11-21-2010, 08:18 PM   #1
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Two circuits in single conduit?

I've only worked with romex homeruns in the past and am new to the world of conduit and THHN so please pardon my ignorance. I would like to have two 20A GFCI outlets in a outdoor two-gang box with a two-gang in-use cover, with each outlet having its own dedicated 20A breaker. Is it legal to run both circuits back to the load center in a single conduit? Do I have to use an additional color to eliminate confusion or can I stick with black and white for both circuits? Finally, can these two circuits share a ground?


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Old 11-21-2010, 08:26 PM   #2
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the MUST share a ground. Yes, you can run multiple circuits in the conduit. No, as long as the neutrals are gray or white and the ground is green or bare, the other wires can be just about any color you want to use.


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Old 11-21-2010, 08:27 PM   #3
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Yes you can run two circuits in one conduit. The ground can be shared.

The neutrals will need to be paired with the respective hot for the GFI to work properly. Simply taping the pairs together is enough.

Two black and white pairs are fine.
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
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Old 11-21-2010, 08:35 PM   #4
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Thank you. Your answers were exactly what I was hoping for.
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Old 11-21-2010, 09:44 PM   #5
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If you are in one of the conduit city codes like Chicago or couple area they will have few extra codes add to it and I know not too long ago someone did asked about the colour codes and I will find it and post it litte later.

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