What Size Ground Wire Should I Use For 8 Gauge Power - Electrical - DIY Chatroom Home Improvement Forum

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Old 07-06-2011, 01:35 PM   #1
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What size ground wire should I use for 8 gauge power

I have a shed that gets power through 10-3 romex in 3/4" conduit from the main box. One of the power wires is no longer working, so I am running a new line. I am hoping to attach the new line to the old line and pull the old line through, using the same conduit.

I want to go from a 30A 220V breaker to a 40A 220V breaker on the main box, and upgrade from 10 gauge to 8 gauge wire. I have been told that going with #8 THHN stranded wires instead of solid romex is going to save me a lot of pain running the wires.

My question is what type of a wire should I run for my ground. I can get 3 #8THHN for both powers and the negative, but can I get away with something thinner for the ground? Currently the ground in the romex is bare. Should I run a bare wire through the new setup or should I just go with a fourth #8 THHN wire? This isn't going through an inspector or code, but I want it to be safe.



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Old 07-06-2011, 02:57 PM   #2
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Two #8 THWN wires in black, one #8 THWN in white, and a #10 THWN green ground. You will also need a 60A (min) panel in the shed with a main disconnect or 6 or less breakers, and two ground rods driven at the shed.


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