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What size wire?

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matt winchel

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I got a electrical question for you. I am wanting to run a electrical wire underground from my current garage to a shed I am building. I do not plan to ever run anything large in this shed just lights and a couple outlets. My garage does have its own power box. I would like to tap into my garage since it is the closest to this shed. Below is what I plan to have for electrical. Can you tell me what size wire I would need to bury to make this happen?



2 flood lights

12 4’ florescent lights up in the ceiling

4 front garage type lights

4 outlets





I am digging a water line in and would love to drop the electrical in the same ditch if possible.
 
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mike93lx

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10 gauge would be rough if you ever plugged in a tool that used 12a, like a saw, large shop vac, heater.

10 uf-b would be my minimum and I would run a 4 wire cable (like 10/3) to give a multi wire branch circuit (2x120v circuits).

If you plan to run any corded tools, step up to 8/3

If you want to run conduit (I would), either thwn or xhhw would be fine
 
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matt winchel

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mike93lx said:
10 gauge would be rough if you ever plugged in a tool that used 12a, like a saw, large shop vac, heater.

10 uf-b would be my minimum and I would run a 4 wire cable (like 10/3) to give a multi wire branch circuit (2x120v circuits).

If you plan to run any corded tools, step up to 8/3

If you want to run conduit (I would), either thwn or xhhw would be fin
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Thanks for getting back to me so soon. This is exactly what I needed to know!
 
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Chuckster in NJ

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mike93lx said:
10 gauge would be rough if you ever plugged in a tool that used 12a, like a saw, large shop vac, heater.

10 uf-b would be my minimum and I would run a 4 wire cable (like 10/3) to give a multi wire branch circuit (2x120v circuits).

If you plan to run any corded tools, step up to 8/3

If you want to run conduit (I would), either thwn or xhhw would be fine
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X2 THIS! ^
8-3 UF. Do it once and do it right……… The extra cost is minimal.
 
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wyliesdiesels

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agree with above.

Do you plan on putting in a breaker panel in the shed or just running everything off 1 or 2 circuits (MWBC)?
 
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LOW1

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I learned the very hard way that it’s difficult to predict future electrical uses and therefore better and cheaper in the long run to oversize electrical instead of having to upsize it later. I would be tempted to install a 60 amp subpanel and the appropriate size wire to feed It.

It looks like 6-3 UF (if that is the size you would need) is about $1.00 per foot more than 8-3.

What you are building to me sounds more like a shop (or potential shop) than a basic shed. Perhaps best to wire accordingly?
 
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cosmokenney

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LOW1 said:
I learned the very hard way that it’s difficult to predict future electrical uses and therefore better and cheaper in the long run to oversize electrical instead of having to upsize it later. I would be tempted to install a 60 amp subpanel and the appropriate size wire to feed It.

It looks like 6-3 UF (if that is the size you would need) is about $1.00 per foot more than 8-3.

What you are building to me sounds more like a shop (or potential shop) than a basic shed. Perhaps best to wire accordingly?
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This is good advice.
 
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Innovate1

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matt winchel said:
So I have had a couple buddies today to tell me to run the 4-4-4 mobile home wire. it is CHEAP! what are your thoughts on that?

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You need 4 conductor cable. And that's URD not MHF - I think that would be ok in 4 conductor but it can't be run inside so you have to convert to something else entering the buildings. Someone more familiar can confirm or correct me on that. MHF typically doesn't come smaller than #2.
 
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Model A Fan

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Based on what you're saying, and potential use (250' from your garage, you'll likely put stuff out there and not want to move it to your garage to us), what others are saying, bigger will be better for you.

Make sure to put the buried wire metallic tape in the ground so someone doesn't dig it up on accident without knowing. 250' is a long stretch to try to guess where/how deep the wires are.
 
OP
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matt winchel

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Model A Fan said:
Based on what you're saying, and potential use (250' from your garage, you'll likely put stuff out there and not want to move it to your garage to us), what others are saying, bigger will be better for you.

Make sure to put the buried wire metallic tape in the ground so someone doesn't dig it up on accident without knowing. 250' is a long stretch to try to guess where/how deep the wires are.Can
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Can I run that cable I put in that link indoors also?
 
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mike93lx

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matt winchel said:
Can I run that cable I put in that link indoors also?
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Likely not. Some URD has a rating for indoor use, but not all.

If you want to go bigger, buy mobile home feeder, which is 4 wires and starts at 2 gauge. What you linked is not mobile home feeder, despite what your buddies called it. It's only for connecting a meter to a main panel, not a subpanel
 
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Model A Fan

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matt winchel said:
Can I run that cable I put in that link indoors also?
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That would be a question for someone with more experience. I come here for all the excellent help the real electricians provide. You're definitely in the right place!

Edit:
mike93lx said:
Likely not. Some URD has a rating for indoor use, but not all.

If you want to go bigger, buy mobile home feeder, which is 4 wires and starts at 2 gauge
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This is what I have running my sub-panel in my barn. I used MHF off a 200A service powering my sub-panel with 90A.

Sub-Panel in Garage-Adding 220v for Table Saw and Air Compressor

A big benefit of running conduit underground as well is being able to get the trunch dug, lay the conduit then backfill. You can then deal with the wiring later. If you run it exposed underground, you have to leave the trench open until the wire is placed. The conduit also protects the wire in...
www.garagejournal.com www.garagejournal.com
 
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75gmck25

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Interesting how this progressed from using a single MWBC (probably 20 amp), to using 2-2-2-4 MHF (90 amps). I think the OP needs to take a good look at future needs and decide how much he wants to put into future-proofing this shed.

IIRC, you can meet the minimum needs by using a single wire run and 20 amp breaker, burying UF-B at 12" or deeper, and using a GFCI in the panel that feeds it. I've always assumed this code item was intended for a structure that just needs a few lights and receptacles for intermittent use. I don't have the exact reference, but this is what I am referring to.

Assuming no panel at the shed - If it was my shed I'd probably want to bury conduit at 18" depth or more and run at least 10 gauge 3 wire UF-B because of the extended distance. Use a 20 amp dual breaker at the garage panel, separate the two circuits (MWBC) out at the shed and wire it with standard 20 amp devices.
If needs to change later I would be able to pull larger gauge wire. However, that's a lot of conduit to bury if its 250 feet away.
 
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mike93lx

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75gmck25 said:
Interesting how this progressed from using a single MWBC (probably 20 amp), to using 2-2-2-4 MHF (90 amps). I think the OP needs to take a good look at future needs and decide how much he wants to put into future-proofing this shed.

IIRC, you can meet the minimum needs by using a single wire run and 20 amp breaker, burying UF-B at 12" or deeper, and using a GFCI in the panel that feeds it. I've always assumed this code item was intended for a structure that just needs a few lights and receptacles for intermittent use. I don't have the exact reference, but this is what I am referring to.

Assuming no panel at the shed - If it was my shed I'd probably want to bury conduit at 18" depth or more and run at least 10 gauge 3 wire UF-B because of the extended distance. Use a 20 amp dual breaker at the garage panel, separate the two circuits (MWBC) out at the shed and wire it with standard 20 amp devices.
If needs to change later I would be able to pull larger gauge wire. However, that's a lot of conduit to bury if its 250 feet away.
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I wouldn't do ufb in conduit. Why fight it and not just run thwn or xhhw? Ufb is terrible to work with and will be a PIA to pull
 
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PCustoms

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mike93lx said:
I wouldn't do ufb in conduit. Why fight it and not just run thwn or xhhw? Ufb is terrible to work with and will be a PIA to pull
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I wouldn't either, but did I miss where he said to run UF-B in conduit?
 
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Innovate1

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That did escalate hugely from 20A to a full 60A sub panel. Really depends on what the OP does down the road. They said shed but that could mean anything. From the lights it could be a 1000 sq. ft. building.
matt winchel said:
12 4’ florescent lights up in the ceiling

4 front garage type lights
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Lots of options have been given which is great and they can now better decide what they are going to do.
 
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sparky 1971

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mike93lx said:
To be fair, 2-2-2-4 MHF and 8/3 UF-B are the same cost.

At least no one said to run a 200a feeder
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I'll do it, I've just been waiting for the invitation. I think the garage should have a new 400 amp service installed, separate from the house, which should also get upgraded to 400A if it isn't already. That way, a 200 amp feeder can be run out to the shed without too much concern about overloading it in the future. You're welcome.
 
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NUTTSGT

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Innovate1 said:
That did escalate hugely from 20A to a full 60A sub panel. Really depends on what the OP does down the road. They said shed but that could mean anything. From the lights it could be a 1000 sq. ft. building.

Lots of options have been given which is great and they can now better decide what they are going to do.
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Yep, a lot of unknown. All we can do advise for the unknown and futureproofing. I think many of us have learned over the years. . . do something like bury conduit, if it's big enough, it can be reused for an upgrade if that time comes.

I mean a little but decent sized load center can be had for less than $50 at a big box store. That's like a trip or two through the Golden Arches drive thru or someone's nicotine habit for a week.
 
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BurtEggley

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analyze the area to determine if there are likely to be rocks, trees etc., sidewalks in the way. Plan on the depth to meet code in your area. I would use PVC conduit. Dig the trench to code depth, and make sure the conduit is properly set in, Use a pull line to pull your cable. 250' is a lengthy pull if there are any bends. Mark the conduit properly for anyone digging in the future and don't forget to pull a permit. Depending how often you plan to use this shed electric, a solar panel and battery on the shed, or a small generator may be less work. Use LED and not fluorescents. I would also lay spare conduit and things like a water line etc., if you might plan on something like that in the future.
 
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Codyboy

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sparky 1971 said:
I'll do it, I've just been waiting for the invitation. I think the garage should have a new 400 amp service installed, separate from the house, which should also get upgraded to 400A if it isn't already. That way, a 200 amp feeder can be run out to the shed without too much concern about overloading it in the future. You're welcome.
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I am running 4/0 mobile home feeder to my shed.
My shed is 2400 sq ft.
 
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sparky 1971

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Codyboy said:
I am running 4/0 mobile home feeder to my shed.
My shed is 2400 sq ft.
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Does that mean you're running a 180 amp feeder? Or is it a 60 amp from two miles away? Conductor size is determined by a number of factors but the service size isn't one of them unless it's the service entrance conductors.
 
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Codyboy

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sparky 1971 said:
Does that mean you're running a 180 amp feeder? Or is it a 60 amp from two miles away? Conductor size is determined by a number of factors but the service size isn't one of them unless it's the service entrance conductors.
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200A breaker at the main , 4/0 to the 200A subpanel.
 
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sparky 1971

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mike93lx said:
Who makes 180a breakers?
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Nobody that I am aware of. But, I've been beat up on here enough about the same thing that I am going to give it back. The official GJ way that I don't follow would be to use 250 AL for a 200 amp feeder or use a 175 amp breaker for the 4/0...

 
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mike93lx

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sparky 1971 said:
Nobody that I am aware of. But, I've been beat up on here enough about the same thing that I am going to give it back. The official GJ way that I don't follow would be to use 250 AL for a 200 amp feeder or use a 175 amp breaker for the 4/0...

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I mean, you kind of deserve it. All that bad advice...
 
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