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wiring my shed for electricity, help

Posted by bob4289 (My Page) on
Sun, Sep 15, 13 at 0:42

I am wanting to run electricity to my workshop that is about 100ft from the house. I dont pretend to know much about wiring so any help would be appreciated. So i have a dedicated 20 amp circuit stubbed up at the side if the house from the main panel. I want to run from that out to the shed. to maybe a sub panel with 4 or 5 20 amp circuits. I'll need about 3 or 4 outlets in the work shop each with there own circuit and one 15 amp for lights. Thats about all the info i have. thanks for the help in advance!


Follow-Up Postings:

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RE: wiring my shed for electricity, help

You'll want to start by defining you needs. Are you planning on using several high draw tools at the same time? Do you need 240v for anything, now or in the future?

Without a subpanel you are limited to two 20 amp, 120v circuits using a multiwire branch circuit. Beyond that you'll need to subpanel (maybe 60 amps) and drive a couple of ground rods and make the appropriate connections to them.


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RE: wiring my shed for electricity, help

With that kind of length, you'd want to size up the conductors a bit to avoid excessive voltage drop. You will need #10 (while #12 would be legal, it would have substantial drop).

This 20A circuit, is it 240? To install a subpanel you'll pretty much need it to be. However, with 4 receptacles and a light you really don't need a subpanel. Run it as a single MWBC. This will preclude you having to install a grounding system (rods) out at the shed.

You'll need some wet rated cable (such as type UF) buried down 24" (you could go only 12" if the thing is GFCI protected at the house end). Conduits could be shallower depending on what they are made out of.

Unless you are solely working with hand tools, you may be underestimating the power you are going to require.


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RE: wiring my shed for electricity, help

thanks for the input. I will be running power tools such as saw and drill, but never more than one at a time. the only other thing running would be light and maybe a small window a/c or space heater.


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RE: wiring my shed for electricity, help

Both a window AC or space heater will chew up pretty much all of that 20A on it's own.


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RE: wiring my shed for electricity, help

if it's too much trouble or too much money i may not run the a/c or heater


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RE: wiring my shed for electricity, help

Years ago I was doing some work in a guy's garage where he had set up a little workshop. It was served by a single 20 amp circuit. It was winter and we had the choice of light and heat or light and the tablesaw. No heat and tablesaw. ;-)


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RE: wiring my shed for electricity, help

so im trying to decide between a subpanel or a Multi-Wire Branch Circuit. Any advice? also have a 30 amp circuit i could run power from if that helps.


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RE: wiring my shed for electricity, help

At 30 Amps / 240V you are to the point where a subpanel might be interesting. You could get the space heater going and still have the lights and a small power tool or two.

Of couse the wiring will need to be larger and you will require a grounding system. Frankly, that's not the worst thing you'll have to do.


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RE: wiring my shed for electricity, help

Get out your measuring tape again. If it is about 100' that is a big uncertainty wrt cost. If you need more than a 100' length, you have to buy 250' at the big box. At 100" the difference between 12 and 10 is not much. At 250", it will be $100.

A sub panel will only cost you $30 and then there are the breakers. Adding a panel will cost more for breakers.

@ <100' with rocky ground (harder to do-over later), there is no way I would not add a sub panel

@ >100' with sandy soil (easier to do-over later), maybe I'd put in a MWBC


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RE: wiring my shed for electricity, help

Get out your measuring tape again. If it is about 100' that is a big uncertainty wrt cost. If you need more than a 100' length, you have to buy 250' at the big box. At 100" the difference between 12 and 10 is not much. At 250", it will be $100.

A sub panel will only cost you $30 and then there are the breakers. Adding a panel will cost more for breakers.

@ <100' with rocky ground (harder to do-over later), there is no way I would not add a sub panel

@ >100' with sandy soil (easier to do-over later), maybe I'd put in a MWBC


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RE: wiring my shed for electricity, help

P,S., buy a heat pump window unit for heat.


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RE: wiring my shed for electricity, help

ok, so i'm getting ready to start everything and just want to make sure im doing it right. Im using a 30 amp circuit to run out to the shed and a 100a subpanel.

1. what gauge wire should i run from the house on a 30 amp circuit? and should it be indoor or outdoor rated?

2. How deep do i need to bury it and what type of conduit should i use?

3. Does it need to be GFCI protected?

Im taking the panel to an electrician friend to wire it, he cant come out so i'll just mount it and connect the wires, and ground. thanks for any input you have!


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RE: wiring my shed for electricity, help

oh and also, it is 175 feet from house to shed.


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RE: wiring my shed for electricity, help

Accessory buildings at or below grade require GFCI on all 120V 15 or 20A receptacles.

There's not really an "outdoor" rated wire. What you need is WET rated (and possibly sunlight rated if it is going to be exposed).

How deep depends on what kind of cable/conduit you are putting in. Direct bury under just lawn is 24". Conduit goes between 6-18" depending on what kind of conduit.

175 is a long distance, to avoid excessive drop, 6 gauge would be advisable.


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