Main Service upgrade and Shop project

Old 01-26-03, 09:11 AM
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Question Main Service upgrade and Shop project

Hello everyone. I intent is not to bother anyone, but I have a Several questions about upgrading my house service and new shop wiring. A little background. The house is block, built in 1971, 125A service. It sits on 2 acres, and I have recently completed a 2000 sqft Steel building to house my "Car Hobby" stuff.

I have spent some time with the local Lowes, and got good advice and a parts list for the following, New 200A oustide Panel, new 200A Meter base, offset etc.

Problem 1. The existing service is located within 30" of my well water storage tank, so the minute I touch it, it has to be moved- (not within current code). I have decided on a new meter base, offset into the 200A panel, 2-100 Breakers, one subfeeding my exsting house panel, and the second for my shop.

Question 1. - What size wire should I use to subfeed the house. I will come out of the side of the panel with an LB, and up to the top of the block, in PVC through the addic, and down to the existing house panel. The total distance is about 20 feet.

Question 2. - What size wire should I use to run 100A back to my shop. It also will be run from the Panel with an LB, up and through the addic in 1-1/2 PVC, to the other side of the house (far corner closest to shop), down the back wall, sweep 90 undergroud, and out to the shop, sweep up, and LB into the steel building. The shop sits 85 feet from the house, so with the through the addic, total distance is about 140-150 feet.

Question 3. - The shop will have a 100A panel, and as I said, it is a steel building without interior closed walls, just the outside walls. The shop is completly sealed from the elements, and I will be running 1/2 or 3/4 emt inside the shop depending on the number of circuits/wires in the conduit. I have a 220 compressor that will pull 24.4A at startup, and run with 13A, and I would like to share that circuit with a 220V Stick Welder. I hardly ever use the stick welder as I have a 120V-20A Mig that I use for my welding. The stick was my dad's, and I would like the ability to use it if a friend needed it. Both the compressor and the Stick welder will NEVER be used at the same time. Is it okay to share the circuits?

Thanks for any help ya'll can provide. I realize that it is a lot of work, but I am confident I can proceed. I am not scared of the project, but do have a substancial amount of respect for electricity. Thanks again... Jim
Old 01-26-03, 11:06 AM
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(#1) I say 3 #3 thwn and 1 #6thwn green in 1 1/4"sch.40 pvc (there will be some that say that table310.15(B)(6) applies and #4 wire)
You will need separate neutral and ground bars at the panel because it is considered a subpanel.

(#2) 3#2thwn and 1 #6thwn green in 1 1/2"pvc

(#3)Not sure of welder requirements(probably 240volt 50 amps)
Old 01-26-03, 11:15 AM
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On your question #3.... the standard for the average stick welder is a 240 volt/50 amp circuit and would not really be suitable for your commpressor connection. I would suggest just running a seperate circuit for it, and also a seperate circuit for the compressor.
Old 01-26-03, 11:51 AM
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Alsoo.... If the wire sizes reccommended aren't available in your area, it is generally better to go up to the next available size. i.e.3 #3 thwn and 1 #6thwn green. If the #3 isn't available, it is best to go to #2 but make sure you stay below the maximum fill of the conduit. You might want to consider using a 1 1/2in sched. 40 PVC conduit for a easier pull.
Old 01-26-03, 08:16 PM
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Thanks guys, you are great!!! I also forgot to ask about grounding the shop.

I had the final inspection done on the shop a year ago, without power. (I needed to fill it so I could stop paying rental on commercial space.)

Other than a grounding rod (or two if recommended), is there anything special I should consider and where should they be placed?

Thanks again.

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