Ground wire

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Old 03-06-08, 06:08 PM
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Ground wire

I am installing a subpanel to exterior building. I will run a 6-6-6 with a 60 amp breaker to protect the wire. I will install ground rods at the outbuilding plus run a ground back to the panel as well.

I will also run a .75" conduit for communicatons at a later date.

1) What is the minimum wire for ground back to the panel? Is there any advantage to using 6 awg for the ground?

2) Is 1.25" conduit big enough to pull through? With 4 #6AWG THHN, this gives me a 17% conduit fill.
 
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Old 03-06-08, 08:03 PM
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my code book tells me that you can use a #8 copper wire because your service wires are less then #2 awg.

depending on your type of conduit, i spec'd emt conduit that puts you at 34% fill, but it doesn't matter, 1 1/4 is large enough no matter the material its made of.

just out of curiousity, what type of service wire are you running to your building, triplex, usc, uf?
 
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Old 03-07-08, 09:31 AM
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The minimum equipment ground (main panel to outbuilding subpanel) for a 60A feeder is #10 copper or #8 aluminum. 1.25" conduit is plenty large enough. There is really no advantage in using larger than #10 for the EGC.

The grounding electrode conductor (subpanel to ground rods) must be #8 or larger copper. I alway use #6 because it doesn't require conduit for protection whereas #8 does.
 
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Old 03-07-08, 08:06 PM
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Thanks Ibpooks for the info.

I will be using THHN. This is a detached outbuilding.
 
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Old 03-07-08, 10:12 PM
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Just make sure you get the THHN wire marked both THHN/THWN due you have underground conduct which it is automatically wet location.


Merci, Marc
 
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Old 03-08-08, 05:48 PM
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H Mrc. It is good to "see" you. The wire is THHN, it is not listed as THWN. I thought the THHN is dual rated for wet locations?
 
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Old 03-08-08, 05:52 PM
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The wire is THHN, it is not listed as THWN. I thought the THHN is dual rated for wet locations?
Usually it is dual rated, but not always....

Grab a magnifying glass and look at the writing on the wire....this will tell you for sure...If it doesnt say THWN anywhere , then it isnt.
 
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Old 03-09-08, 12:53 AM
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Useally the THHN genraly is a dual rated but i really advise you make sure it have THWN marking on it because some area the inspectors can get really picky on this and can really make the day really sour if you don't check this ahead of the time.

Belive me it did happend to me before.

Merci, Marc
 
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