Putting in a 100 AMP Subpanel


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Old 11-05-17, 12:38 PM
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Question Putting in a 100 AMP Subpanel

We'll I've been researching a lot on how to install a 100 amp service sub panel in my woodworking workshop to include reviewing the 2012 Virginia Residential Code.
I have a 200 AMP Main service (Homeline) and I'm aware that I have to install a 100 AMP double-pole feeder breaker for the workshop.
I plan on buying a Siemans 24-circuit 12-space 100-amp main breaker box. I'm doing this so I can have one switch to cut off. I will also add 2 15 amp breakers for lights and 2 20 amp breakers for plugs. You may think this is over kill but I'm doing it this way for future expansion.
Additionally I plan on putting in 2 8-ft cooper grounding rods no closer than 6 feet to each other, per code and will use #6 wire for this.
The workshop is 50ft from the Main breaker and I plan on digging a 18" deep trench and putting the wire from the house to the workshop in it using Schedule 80 PVC. I've read that I could use Schedule 40 PVC underground but have to have Schedule 80 when it comes out of the ground.
Ok now my issue, I've seen too many answers on the wire I have to pull from the house to the workshop and would like to have what I think I need confirmed.
I plan on using 4-4-4-6 THWN-2 wire, but the other options I've seen are 3-3-3-5 THWN-2.

Which one do I really need to use?

Derek
Woodbridge VA
 
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Old 11-05-17, 02:05 PM
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For 100A if using copper you need three #3 and one #8 for the EGC. If using aluminum you need three #1 and one #6 for the EGC. Electrode conductor for the rods is bare #6 copper. Trench needs to be deeper than 18", code requires 18" of cover.
 
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Old 11-05-17, 06:23 PM
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If using copper wire, use THHN/THWN

If using aluminum use XHHW or USE
 
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Old 11-06-17, 07:51 AM
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Be aware that USE only rated wire is not to enter the structure. You want multiple rated such as RHH/RHW/USE which is direct bury and only needs to be in conduit where above ground. XHHW needs to be completely in conduit.
 
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Old 11-09-17, 03:16 PM
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Thanks! You gave me the answer I was looking for!
 
 

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