Installing Subpanel

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  #1  
Old 06-01-01, 03:22 PM
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Question

I have a large collection of woodworking tools. The new house I moved into has a garage that is not wired to handle them (all 4 outlets come off of a single 20A breaker). To make life easy, I want to install a subpanel off of the main panel (there are 8 open slots). Based on the loads of the equipment I estimate I need 4 breakers in the subpanel: a 220v/30A and 3 110v/20A. Maximum running load at any given time is about 50A (the 220v load and a 110v load). Local contractors/electricians want $500 and won't discuss the how-to's with me. I have a lot of experience with wiring and have the basic know-how of installing breakers, but not subpanels. Guidance would be greatly appreciated.
 
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  #2  
Old 06-01-01, 04:28 PM
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Can't help you alot here. I too, am thinking to rewiring my garage to have subpanel in it. Only one suggestion: Have lighting on its own circuit. Mine isn't right now and once in a while will blow breaker when running power tools. Nothing worse than waiting for tool to wind down while standing in the dark
 
  #3  
Old 06-02-01, 08:24 PM
RickM
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Cool

I would say that spending the $500 seems to be a fair way of getting this work do, and (hopefully) done correctly. there are alot of variables that go into adding a subpanel, as you can tell from all the different posts here concerning subpanels. check out these posts, and then decide if it is worth it to try it yourself. sure it can be done yourself, but is it worth it? Your call.

Either way, good luck.

Rick Miell
 
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Old 06-02-01, 10:23 PM
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Well, I did a lot of research and think I've got most of it understood. The one question I'm not sure about is connecting the subpanel to the main. I'm installing an 50amp, 2 pole breaker - that will have the red and black wires. Those in turn will connect to the main lugs (L1 & L2) on the subpanels main disconnect. But now I have a white (neutral) and a ground (bare copper). In the main panel the neutrals and grounds are hooked into the same bus bar.

So...do I only need to connect the subpanel using 3 lines (red, black, and ground)??? I bought 6-3 wire, so now I'm going to have that extra white. Is this correct?

And do I have to use the grounding bolt in the subpanel with it connected this way?

Again, any input would be greatly appreciated.

Doc
 
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Old 06-02-01, 10:48 PM
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Q: So...do I only need to connect the subpanel using 3 lines (red, black, and ground)??? I bought 6-3 wire, so now I'm going to have that extra white. Is this correct? And do I have to use the grounding bolt in the subpanel with it connected this way?

A: No, not correct. You will use all four wires. The white wire connects to the neutral bar, and the grounding wire to the grounding bar. Do not use your main panel as a model for your subpanel!!! In the subpanel, you must keep the neutral and the grounding bars electrically isolated. Throw away the green bonding screw that came with your subpanel!!! Do not use it!!

 
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Old 06-02-01, 10:59 PM
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Thanks John. But to clarify, if you will please indulge me:

I'll need to purchase another bar for the subpanel. So I'll have 2 - 1 of the grounds and 1 for the neutrals.

But in the main panel where do I hook the neutral and the ground to (coming from the subpanel)? As I said, right now there is only 1 bar in there with both grounds and neutrals hooked to it.

Thanks for your time.

Doc
 
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Old 06-03-01, 01:01 PM
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In the main panel, you can connect neutral (grounded) and bare (grounding) wires to the same bar. In the subpanel, you cannot. Clear enough?
 
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Old 06-03-01, 02:24 PM
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Crystal...

Thanks John, I appreciate your time and assistance.

Be well,

Doc
 
  #9  
Old 06-03-01, 10:14 PM
Wgoodrich
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Just some added thoughts that I feel should be said to get people to thinking.

Why the sub panel?

It seems that many people jump to installing sub panels where the are seldom needed.

If this garage is attached, why not run four romex cables to your attached garage direct from the panel. If you compare the cost factor, you should find a substatial savings. Four 12 ga. cables run all at once is easier, faster, and cheaper than one large feeder cable.

If this garage is a detached garage, I see a potential problem. You said you are running a 6/3 wire. Is this going to be an above ground installation or underground installation. This 6/3 wire must be approved for the purpose considering the wiring style that you are installing it in.

Hope this helps

Wg
 
  #10  
Old 06-03-01, 10:33 PM
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WG, I am renting a house with a 2 car garage that is under the house. It has 4 outlets in it, which are wired into the same 20A circuit as all 3 bedrooms. If I turn my miter saw on (110v/15A) it pops the circuit every time.

Additionally there are no 240v circuits in the garage and the main panel only has 2 openings (adjacent to one another, thankfully).

So, to install a 50A, 2 pole breaker in the main and run a 6/3 wire 4 feet along the inside wall to the sub is the easiest. I've already picked up all the wire, boxes, outlets, breakers, and 100A panel that I need - total cost: $120 (and that was including 250 feet of 10/3 NM). What my plans are is to install everything external to the walls so that way, when I leave, I can take it all with me.

Just to set everyone's mind at ease, I'm having an electrician come and check everything out for me before I actually install the breaker into the main and connect the sub. Don't need any mistakes.

Oh, and this also keeps the lighting on a separate circuit.

Thanks for everyone's time and input.

Doc
 
  #11  
Old 06-04-01, 05:46 PM
Wgoodrich
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Now I am probably going to sound like a lawyer but it is not intended that way. I am a landlord and think along this line concerning repercussions where there is an action.

You might want to get a written approval from your landlord to ensure no come back due to you causing damage to the structure.

You might also consider that on normal occasions anything mounted to the structure, even carpet if permentantly installed would be considered a part of the structure becoming the property of the landlord.

Just some precautions for you to think on.

Also check with your local inspector to make sure of any required permits or inspections you need to adhere to. The fines for such violations of building, plumbing, or electrical laws are quite salty.

Just be sure to protect thyself concerning law and liability concerning your project in a building owned by others.

Good Luck

Wg
 
  #12  
Old 06-04-01, 09:48 PM
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:-)

WG, thanks for the reminder, but already well ahead of you. I have already talked with the owners, not the realtor about it and they have no problems with the installation, so long as I get it inspected and have the appropriate permits. As for keeping it, they actually gave me the option, that if I leave it installed they will pay the cost of the materials or I can just uninstall it and take it with me (excellent owners).

I'll be completing this installation (complete with permits and inspection) during the week. Can't wait to start making sawdust this weekend.

Thanks to everyone for their time and input, it was greatly appreciated.

Be well all...

Doc
 
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