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Old 04-20-2009, 01:28 PM   #1
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Sizing wire/breaker to new shop.


I am building a new 16' x 20' workshop, for small DIY projects. I don't expect to do any welding, or anything that requires more than what a portable tool will draw. I do want to have a 220v outlet in the new shop though. My main house service panel is 200 amp, and is located about 100 ft from where the new shop panel will be. Half of the 100 ft will be under-ground. I am thinking that 60 amps in a smaller service panel in the shop would be sufficient to handle the circuits for the lights, outlets, window A/C, etc. Do I put a 60 amp breaker in the main house panel, and 15 & 20 amp breakers in the shop panel, or do I also need a 60 amp breaker as a main breaker in the subpanel? What size wire do I need to run from the main house panel to the new subpanel in the shop? Can I run unshielded wire if in pvc conduit?

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Old 04-20-2009, 07:28 PM   #2
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Sizing wire/breaker to new shop.


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I am building a new 16' x 20' workshop, for small DIY projects. I don't expect to do any welding, or anything that requires more than what a portable tool will draw. I do want to have a 220v outlet in the new shop though. My main house service panel is 200 amp, and is located about 100 ft from where the new shop panel will be. Half of the 100 ft will be under-ground. I am thinking that 60 amps in a smaller service panel in the shop would be sufficient to handle the circuits for the lights, outlets, window A/C, etc. Do I put a 60 amp breaker in the main house panel, and 15 & 20 amp breakers in the shop panel, or do I also need a 60 amp breaker as a main breaker in the subpanel? What size wire do I need to run from the main house panel to the new subpanel in the shop? Can I run unshielded wire if in pvc conduit?
You can get what they call a main lug sub-panel for the shop. So put the 60 amp breaker in the house and it will hook directly into lugs in the shop panel. The only way to kill the power to the shop will be from inside the house panel though.

I would only use 12 gauge wire in the shop so you will not need 15amp breakers.

Yes you can run loose THHN wire in your conduit. Needs to be at least 18" deep.

You will need 3 #6 wires and 1 #8 for your ground. Run it in 1" conduit.

And make sure you separate your ground and neutrals in the shop panel.

And also be sure to flag your neutral in white electrical tape on both ends.

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Old 04-21-2009, 11:19 AM   #3
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Sizing wire/breaker to new shop.


You also need to drive at least one ground rod maybe two at the workshop. And connect it to the ground terminal lug bar in the sub panel. 60 amp is a good choice for the loads you describe. Like said above get a 60 amp main breaker panel. Sub panels and main panels are constructed the same. They are wired differently as already mentioned. Good luck.
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Old 04-21-2009, 11:51 AM   #4
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Sizing wire/breaker to new shop.


Thanks.
Can I share the conduit with coax and 18 ga control wires without interference to the coax signals? I could run 1 1/2 inch conduit. I have one 2" pvc "hole" in my poured wall 2 ft below grade for my buried wires, etc.
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Old 04-21-2009, 01:32 PM   #5
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Sizing wire/breaker to new shop.


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You will need 3 #6 wires and 1 #8 for your ground
#10 ground

Quote:
And also be sure to flag your neutral in white electrical tape on both ends.
Technical foul........but I'm not saying don't do it.


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Can I share the conduit with coax and 18 ga control wires
Not unless you have some kind of super cable that is insulated for 600 volts. Run separate conduit for data/com
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Old 04-22-2009, 10:54 AM   #6
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Sizing wire/breaker to new shop.


You can share the same trench. So run another PVC line along with the one you are installing.
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Old 04-22-2009, 12:17 PM   #7
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Sizing wire/breaker to new shop.


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You can share the same trench. So run another PVC line along with the one you are installing.
I will have to go through the same 2" hole in the poured wall below grade. Will this be a problem?
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Old 04-22-2009, 12:27 PM   #8
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Sizing wire/breaker to new shop.


Quote:
Originally Posted by thefamouscbc View Post
You can get what they call a main lug sub-panel for the shop. So put the 60 amp breaker in the house and it will hook directly into lugs in the shop panel. The only way to kill the power to the shop will be from inside the house panel though.
A main disconnect is required at the detached structure, a main lug panel would either need a backfed breaker with the hold-down kit or a separate disconnect before the panel.

Edit: the main disconnect at the detached structure must be rated for a minimum of 60 amps (even if you only feed the detached structure with a 30 amp service). This disconnect serves only as a disconnect for the detached structure, the OCPD (Over Current Protection Device) is installed in your main panel to protect the wires from over-current.

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I would only use 12 gauge wire in the shop so you will not need 15amp breakers.
You can run 12 guage wire on 15 amp circuits, the only real benefit here is that you don't buy 14 guage wire. Its up to you what you need for circuits and how much wire you are buying.

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Yes you can run loose THHN wire in your conduit. Needs to be at least 18" deep.
No, it MUST be THWN, Not THHN. Most wire nowadays is dual rated THHN/THWN, but if you feed individual wires in the conduit it must be rated THWN.

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Originally Posted by thefamouscbc View Post
You will need 3 #6 wires and 1 #8 for your ground. Run it in 1" conduit.

And make sure you separate your ground and neutrals in the shop panel.

And also be sure to flag your neutral in white electrical tape on both ends.
Good, except you cannot re-code any wire under 4 gauge, to take a 6 guage black wire and color code it white would be a violation. Most people would argue that its a small petty thing in which I would agree, but the code states this size wire cannot be re-color coded.

Last edited by theatretch85; 04-22-2009 at 12:39 PM.
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Old 04-22-2009, 12:29 PM   #9
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Sizing wire/breaker to new shop.


The only problem may be squeezing the two conduits thru it. If they fit, you are good.

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