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Old 06-22-2013, 03:20 AM   #1
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100a sub panel install questions?


Hey all, thanks in advance for any info in advance. The power running to my detached shop is only 30a and pretty damn sketchy. I have to update it for my renovation. I've done a bunch of research and I'll lay out my plan but I'm hoping that you can point out anything I've missed, this is the first time for me doing any major electrical.

From my 200a main breaker box I'm going to hook up a 100a 240v breaker and run a 3 - 2g and 1 - 4g bare ground aluminum service feeder wire and run that through schedule 40 1 inch PVC to my shop. That is going to feed a 100a main breaker box in my shop. From there I plan to run 3 - 30a 240v breakers (2 for hid lighting and 1 for a mini split AC unit). I also plan on running 2 - 20a 120v breakers for wall plugs.

So far I've noted that the neutral and ground bar are not supposed to be bonded on the shop breaker box and that aluminum wire requires special lubricant at the terminals. Also since it's about a 100' run from house to shop I should get a second ground rod for the shop. Thanks a lot guys!

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Old 06-22-2013, 04:59 AM   #2
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100a sub panel install questions?


Quote:
Originally Posted by NWDubCollective View Post
From my 200a main breaker box I'm going to hook up a 100a 240v breaker and run a 3 - 2g and 1 - 4g bare ground aluminum service feeder wire and run that through schedule 40 1 inch PVC to my shop.
I don't have a code book handy. So I can't comment on wire sizes. However, 1 inch PVC is way too small. And, as a rule of thumb, PVC above ground should be sch 80.

By "service feeder wire" do you mean USE cable? Cable sleaved in conduit above ground and for 18" as it dives into a trench is necessary. But trying to pull cable through an entire conduit system is a really bad idea.

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Originally Posted by NWDubCollective View Post
So far I've noted that the neutral and ground bar are not supposed to be bonded on the shop breaker box and that aluminum wire requires special lubricant at the terminals.
The antioxidant paste is not required, but it couldn't hurt. The terminals are required to be torqued to spec. You'll need a torque wrench.
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Originally Posted by NWDubCollective View Post
Also since it's about a 100' run from house to shop I should get a second ground rod for the shop.
Two ground rods.

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Old 06-23-2013, 12:24 AM   #3
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100a sub panel install questions?


Ok, I can go with a larger PVC no problem, is sched 40 ok for under ground though? I'm very lucky to have a good friend who does directional boring and can run any size PVC needed with out digging a trench. I've watched some how tos on how to waterproof wrap and connect conduit and run it into the house correctly.
This is the wire I was looking at getting, it's listed under "service wire" at platt.com.
http://m.platt.com/platt-electric-su...spx?pid=062444
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Old 06-23-2013, 12:24 AM   #4
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100a sub panel install questions?


Oh and do I need two ground rods for the shop only? I already have a ground at the house.
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Old 06-23-2013, 09:42 AM   #5
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100a sub panel install questions?


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Originally Posted by NWDubCollective View Post
Oh and do I need two ground rods for the shop only? I already have a ground at the house.
Code requirement. Actually code says prove 1 rod (at 25 ohms or less) or 2 rods. Easier to install 2 rods and be done with it.
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Old 06-23-2013, 10:06 AM   #6
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Originally Posted by NWDubCollective View Post
I'm going to hook up a 100a 240v breaker and run a 3 - 2g and 1 - 4g bare ground aluminum service feeder wire
You will need 4 conductors, 2 feeds, 1 neutral, and 1 ground.
Neutrals and grounds need to be separated at sub panels.
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Old 06-23-2013, 04:08 PM   #7
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Quote:
Originally Posted by NWDubCollective View Post
Ok, I can go with a larger PVC no problem, is sched 40 ok for under ground though? I'm very lucky to have a good friend who does directional boring and can run any size PVC needed with out digging a trench. I've watched some how tos on how to waterproof wrap and connect conduit and run it into the house correctly.
This is the wire I was looking at getting, it's listed under "service wire" at platt.com.
http://m.platt.com/platt-electric-su...spx?pid=062444
Two things:

1) The wire you referenced is NOT listed for underground installation. Choose another type of wire, such as type XHHW or THWN if installed in underground conduit.

2) #2 aluminum conductors are not rated for a 100 Amp service. You will either have to install a larger conductor (#1), or a smaller breaker on the originating end (90 Amps), or use copper wire (#3).
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Old 06-25-2013, 12:52 AM   #8
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100a sub panel install questions?


Thanks guys! I can do 90 amps no problem, get two grounds, and voila! I found USE individual wire cheaper anyways, thanks for the heads up, but will USE be ok to use as a ground? Would a bare ground wire be ok? Thanks again, about to crack into this project.
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Old 06-25-2013, 05:54 AM   #9
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100a sub panel install questions?


I would not recommend using a bare aluminum conductor for a ground.

If you want to use aluminum conductors, then type USE for your grounding conductor is fine.

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