Wiring Shop Sub-Panel questions

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Old 06-24-17, 03:06 PM
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Wiring Shop Sub-Panel questions

Hi everyone. I'm new here and would appreciate your input on wiring a sub-panel in my shop. To preface: An electrician will do my hook-up at the main and at the sub-panel. I'm in the planning stage and trying to determine an estimated supply budget. I live in a rural area, so there are no permits or inspections. I do, however, want this to be safe. In the shop, I will have (2) 2'x4' LED Fluorescent style fixtures and 4 receptacles. For demand, I will run a standard WalMart box fan, power tools and a small pancake compressor. The 2 largest loads would be a portable planer (15 amps) and the compressor (10 amps). The max that would run at one time is the fan, planer and if the compressor happened to turn on. Our plant engineer helped me with this, but I still have a few questions. The basic plan is to run 220 and then split it at the shop into (2) 110 circuits. All wire will be copper.

At my meter, I have a panel with only a main disconnect breaker for my entire house. (The breaker panel for each circuit is in the center of the house and not very accessible.) My unattached shop is 12'x20' and is a 215 foot wire run from the meter. My plan is to install a small disconnect panel off of my main disconnect at the meter. From there run 1" PVC conduit underground to the shop. I would pull (2) Black #6 THWN and (1) #8 copper ground.

At the shop, install a new sub-panel with a 50-amp 2-pole main breaker and 3 single pole breakers. The hots would be split from the 50-amp to the breakers. I'll put 2 breakers on 1 circuit and one breaker on the other. That way I can run my planer and compressor so they don't run on the same circuit. The ground from the source goes to the bus bar (and on to an 8 foot ground rod). A neutral (white) would run from each breaker back to the bus. From the breakers, I would wire the lights and receptacles with 12/2 Romex.

My main question: Is it correct that a ground should run with the 2 hots in the conduit, or should it be a neutral? I would think a neutral would make the long run and then tie in the ground at the bus, but I'm not proficient with 220 circuits.

Is the #6 THWN okay for the 215 foot run? I know voltage drop is a real issue, but I won't be running any equipment with a really heavy demand.

Is there anything else you would recommend or that I missed? I couldn't attach the diagram due to size, but put it on Photobucket here:


http://i1076.photobucket.com/albums/...pse78zyhp3.jpg

Thanks so much for any help and advice!!!
 

Last edited by ray2047; 06-24-17 at 04:36 PM. Reason: Add image.
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Old 06-24-17, 04:18 PM
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To preface: An electrician will do my hook-up at the main and at the sub-panel.
Some electricians won't want to take the liability of finishing someone else's work. It will be their name on the permit and their license on the line. Actually hook up is the easiest part and within DIY capabilities.
The basic plan is to run 220 and then split it at the shop into (2) 110 circuits. All wire will be copper.
Nominal voltages are 120v and 240v. Yes, you will need a subpanel. Usually a 100 amp main breaker panel is used because it provides ample spaces for branch circuit breakers and the 100 amp main breaker acts as the required disconnect. You do not need to supply a 100 amp subpanel with 100 amps. The breaker in the main panel can be much smaller. Another advantage of the 100 amp main breaker panel is cost. A main breaker panel kit contains an assortment of branch circuit breaker and is usually the cheapest way.
The ground from the source goes to the bus bar (and on to an 8 foot ground rod).
You will need to buy and install a ground bar. The ground bar is bonded and the neutral bar isolated.
Is it correct that a ground should run with the 2 hots in the conduit, or should it be a neutral?
YOu need four wires, hot-hot-neutral-ground.
Is the #6 THWN okay for the 215 foot run?
#6 would be okay on a 40 amp breaker (3.5% drop at 40a) at the main panel. Since you are upsizing the conductors you would need a #8 ground.

Re your diagrams. Both of the subpanels need ground. The subpanel on the pole can use a metal conduit as the grounding means but if PVC is used to the shop it must have four wires.
 

Last edited by ray2047; 06-24-17 at 07:50 PM.
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Old 06-25-17, 08:41 AM
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Thanks for the input. I sincerely appreciate it! The electrician is a friend and as I said, luckily there are no permits here. I'm familiar with voltage, 110/120 & 220/240. I have no idea why, but around here everyone uses 110/220. I'm in Mississippi, so that may explain it!
I was looking at the subpanel wiring diagrams you have at the top of the forum. I think what I was told is probably the Pre-2008 wiring where the ground doesn't have to run in the conduit. He told me to run 2 hots and a ground, but I think he meant 2 hots and a neutral. That makes more sense and had me confused.
Thanks for the info regarding the grounding rod at the meter. I had thought the new subpanel ground at the meter would simply be tied to the existing main disconnect ground. I didn't know it needs a separate ground, but that is easy enough to do!
Thank you again for the help. It's nice of you to take the time to deal with us amateurs!
 
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