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Discussion Starter · #1 ·
I will be running a 60 AMP 240V circuit about 25' for an electric boiler. From what I am seeing I would need to use 4-3 NM rated up to 70A, or I could use #6 THHN 90 deg rating at 75A.
I'm thinking that the THHN would be easier to work with rather that that big Romex. I would need to run a 1" PVC conduit with just 2-90 deg elbows for an easy pull. If I do go with the THHN and pull it, both hots and neutral need to be #6 THHN, can the ground be smaller? and would it need to be insulated or could it be bare?

I've never worked with Romex that big and it just seems like it would be a bear to work with, I appreciate any advice from anyone who has some experience.
 

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Ground can be smaller and can be bare. If you are running conduit out there I am pretty sure romex can not go in conduit. So it would have to be suitable for either direct sunlight or burial.
 

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Master Electrician
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You can not use a 90 degree C rating unless all of your terminals are rated for 90 degrees. Why do you need a neutral?
 

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Licensed Pro
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If it's a straight 240V boiler you don't need a neutral... just two hots and a ground. 6ga THHN would be appropriate if in conduit.
 

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The only reason you would need a neutral is if it had 110 volt controls and no control transformer installed on the boiler itself.
 

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Discussion Starter · #7 ·
Thanks for clearing that up everyone. Three #6 conductors, ground will get marked with green tape, 1" PVC conduit.
 

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Electrical Contractor
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You only need a #10 ground on a 60 Amp circuit. 2 hots of #6 and a #10 ground.
 

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The #10 should be green, not taped green.
 
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