Adding power to a shed

[66slabside]

Good afternoon Garage Journal.

I have a friend who is wanting me to help him run permenant power to his shed, sized 10X15, he's tired of running extension cords out there all the time.
He only needs one 20 Amp circuit to operate one 4 Ft LED strip light, a small 3 blade ceiling fan and a couple of outlets for a radio and small items while he's out there polishing his bike.

I have researched and it seems pretty straight forward. My questions are about running the wiring to the shed. I used a wire sizing calculator, grounding conductor chart and a conduit fill chart I found online.

Including all footage from panel to shed we have 150 feet to cover. My research has lead me to to the conclusion that I will need 6 gauge THWN wire with a 12 gauge ground buried in 3/4 inch Sch 40 PVC buried to 18 inches top of conduit.

I'm just not 100% on those sizes and am hoping you guys can hop in and confirm or correct what we need to do this right. Thanks in advance.

 

[pattenp]

#10 is plenty for 20A circuit to account for voltage drop (VD). The ground is also required to be upsized to #10.

Edit: If the circuit is only 120V and 20A or less it can be GFCI protected at the source and then only require to be buried 12 inches.

You can use #6 if you want to, but the circuit shouldn't be maxed out to the 20A for VD to be an issue with #10. A compromise would be #8, that would give you 3%VD at 80% load or 16A.

What ever the increase in size of the current carrying conductors to account for VD you also have to increase the ground. So if you use #6 the ground needs to be #6.

 

[66slabside]

Thank you for the quick reply. I'm no professional electrician but was thinking that #6 was way over kill for that and off the top of my head was thinking 10, maybe 8, would suffice and was the main reason for asking the questions. I've done enough wiring from panels to be confident I can wire in a few outlets and lights but not so much wire sizing on long runs like that. I've only helped others and used what I was told to use.

I did talk to him about GFCI protection right from the source, if it was my house that's how I would do it due to the fact that in my readings I wasn't sure if that was required by code or not these days. I'll let him decide on which way he wants to go. 12 inches of trenching sounds easier than 18 but he's renting the trencher and doing the digging so that too will be up to him.

I did not know about the grounding size so I appreciate the input and will follow accordingly.

Thanks again for your input, I have long been a lurker and reader of the Garage Journal and have always admired everyone's willingness to help.

 

[pattenp]

If the circuit/feeder is not GFCI protected from the source then a GFCI outlet needs to be in the shed protecting all other outlets.

 

[driftpin]

He can have multiple circuits if he goes w/#6 AWG, yes? He can have a small multiple circuit-breaker panel. I'd just as-soon have the potential to have 240 volts out there, so three-wire and ground. I suppose two ground rods should be done at the shed.

 

[u2slow]

For 150' I would run one size larger wire for the ampacity needed (for voltage drop), and a make it a 3 wire circuit. (i.e. #12/3c for one, possibly two 120V/15A circuits; even 240V available if required.) In my experience, as soon as you bring power to new space, somebody wants to run a small heater at least occasionally.

A direct burial cable will save you a few $ over conduit.

EDIT: Ground rods in a shed don't make sense unless you have livestock/chickens in it; and/or a dirt floor. The EGC/bond wire run with the other conductors accomplishes the ground path.

 

[mike93lx]

240v isn't needed in a 10x15 shed, come on guys.

Keep it simple, no breakers, no 4-wire feeds.

I would run 3-#10 stranded thwn in conduit or a piece of 10/2 UF. 20a Gfci in the house, run it into decent size j box. 1 #12 out to a lighting circuit and 1 #12 out to a pair of duplex outlets where ever convenient. Done in a day.

 

[u2slow]

I would still do #12/3 vs #10/2 . The extra conductor can become any of:
- remote switch leg
- extra 120V circuit
- 240V capability

... and doesn't need to be utilized until the need arises.

Still done in a day.

 

[66slabside]

Dang it, I had this long reply and I got logged out and it didn't post!! Here's the short of it since I don't want to post it all again.

He wants conduit because we have to go under his driveway and he will eventually be planting bushes for privacy a few feet away and doesn't want roots to damage wire in the future.

My first suggestion when he asked me for help was go bigger because you may want more in the future. I suggested a small sub panel just because, well, you've already dug a 130 foot trench you might as well over compensate. A small heater, TV, beer fridge, run a vacuum or saw? Who knows what you may want to do in the future but he insisted this was all he wanted.

Once the wire lands in the shed we are going to split it and do one "circuit" with a GFCI and two outlets downline from that. Then the other "circuit" will go to two switches, one for the LED light and one for the ceiling fan. The shed will be wired with #12 and all 20 Amp switches and outlets done in MC because he doesn't want to take any chances with the grand babies accidentally cutting through a cable with a shovel or something.

I'm still going to try to get him to at least run a 1inch conduit for future expansion since it's a lot easier to do it now then dig it all up later.

If anyone else has ideas or suggestions, maybe for pulling wire through 150' of conduit I'm all ears. Thanks again guys, as usual, all help is greatly appreciated and all ideas are food for thought.

 

[alfredeneuman]

I would still do #12/3 vs #10/2 . The extra conductor can become any of:
- remote switch leg
- extra 120V circuit
- 240V capability

12/3? Don't you mean 10/3?
For the extra 120V circuit and the 240V capability you'd have to trench 18" instead of 12" if GFI protected at the source.

 

[mike93lx]

Use a plastic bag and a shop vac to pull a string through the conduit, then use that to pull a heavier rope that actually does the pull. 1" should make that an easy pull

 

[theoldwizard1]

#10 is plenty for 20A circuit to account for voltage drop (VD). The ground is also required to be upsized to #10

UF-B is available in #10.

 

[theoldwizard1]

I would still do #12/3 vs #10/2 . The extra conductor can become any of:
- remote switch leg
- extra 120V circuit
- 240V capability

... and doesn't need to be utilized until the need arises.

Still done in a day.

If you don't install a breaker panel and put power on both sides, you are going to be limited to 15A.

12-3 UF-B is actually cheaper than 10-2 UF-B.

 

[u2slow]

12/3? Don't you mean 10/3?
For the extra 120V circuit and the 240V capability you'd have to trench 18" instead of 12" if GFI protected at the source.

I would run #12 @ 15A OCP. Learned early on my apprenticeship you always pull 'sets' of circuits in conduit. And an extra wire is just a wire. How you decide to use it later is anybody's guess.

GFCI not required here for enclosed outbuildings. Normally bury PT lumber overtop to reduce burial depth. Not sure about NEC.

 

[sberry]

12. I used to do **** like that. The guy has been using cords, a 12 wire will work dandy and be easy simple to do as well as reasonable cost.

 

[mike93lx]

12. I used to do **** like that. The guy has been using cords, a 12 wire will work dandy and be easy simple to do as well as reasonable cost.

I would more readily upsize to 10 than run a 4th wire.

Lots of different ways to do it for sure

 

[sberry]

I got one with 250 ft, works. This would be different if he was in to welding and heavy air compression.

 

[wyliesdiesels]

For 150' I would run one size larger wire for the ampacity needed (for voltage drop), and a make it a 3 wire circuit. (i.e. #12/3c for one, possibly two 120V/15A circuits; even 240V available if required.) In my experience, as soon as you bring power to new space, somebody wants to run a small heater at least occasionally.

A direct burial cable will save you a few $ over conduit.

EDIT: Ground rods in a shed don't make sense unless you have livestock/chickens in it; and/or a dirt floor. The EGC/bond wire run with the other conductors accomplishes the ground path.

You are muddying the water here. Ground rods have nothing to do with preventing fault current from create shock potential. The EGC accomplishes that. Also, grounding rods are not for establishing a low impedance fault current pathway. They are for shunting lightning and surges.

Also, ground rods are not required unless there is a subpanel.

If you don't install a breaker panel and put power on both sides, you are going to be limited to 15A.

12-3 UF-B is actually cheaper than 10-2 UF-B.

why would he be limited to 15a?

 

[66slabside]

I've seen the ole vacuum and bag method before. That's what I'm planning on doing but I'm an, "Ask the guy that's been doing it for years, he probably has an easier way' type of guy. No use reinventing the wheel.

All answers are appreciated and I will give him a few options and see what he wants to do. I'm leaning to three #10 in conduit with a GFCI breaker. I also haven't looked too closely at what type of panel he has but it is an older home, might not even make one for his panel.

He really has no use for 240 V anywhere in his house let alone the shed as he doesn't have a welder or big compressor like us Garage Journal guys and isn't the type of guy who does that type of stuff. He's simply retiring in a few years and knocking out a few projects that's been on the list a while so when retirement gets here he can enjoy what he has. One of them is a ceiling fan for comfort and light for his aging eyes when he's wiping down the bike and polishing the chrome.

Another round of thanks for those who have gone out of their way to help today. All input has been appreciated.

 

[Terry D]

#10 is plenty for 20A circuit to account for voltage drop (VD). The ground is also required to be upsized to #10.

Edit: If the circuit is only 120V and 20A or less it can be GFCI protected at the source and then only require to be buried 12 inches.

You can use #6 if you want to, but the circuit shouldn't be maxed out to the 20A for VD to be an issue with #10. A compromise would be #8, that would give you 3%VD at 80% load or 16A.

What ever the increase in size of the current carrying conductors to account for VD you also have to increase the ground. So if you use #6 the ground needs to be #6.

This is just my own opinion, I personally don't like GFCI protecting underground conductors. Conduits are prone to leak and direct burial is in constant moisture with the soil. Could have nuisance trips down the road. I like putting the GFCI protection out at the equipment or in the out building

 

[mike93lx]

I've seen the ole vacuum and bag method before. That's what I'm planning on doing but I'm an, "Ask the guy that's been doing it for years, he probably has an easier way' type of guy. No use reinventing the wheel.

All answers are appreciated and I will give him a few options and see what he wants to do. I'm leaning to three #10 in conduit with a GFCI breaker. I also haven't looked too closely at what type of panel he has but it is an older home, might not even make one for his panel.

He really has no use for 240 V anywhere in his house let alone the shed as he doesn't have a welder or big compressor like us Garage Journal guys and isn't the type of guy who does that type of stuff. He's simply retiring in a few years and knocking out a few projects that's been on the list a while so when retirement gets here he can enjoy what he has. One of them is a ceiling fan for comfort and light for his aging eyes when he's wiping down the bike and polishing the chrome.

Another round of thanks for those who have gone out of their way to help today. All input has been appreciated.

A sparky can confirm, but I would run it through a gfci outlet somewhere convenient in the house if you cant get a breaker for the panel

 

[66slabside]

I could do that. His panel is surface mounted on a cinder block foundation so we were going to drop down out of the bottom of the panel and then go out the wall. I could use a box and add a GFCI just not sure if I could find a GFCI to accept #10 wire?

 

[sparky 1971]

A GFCI will accept #10. Make sure it's stranded wire though. It most likely will be but just make sure. There has been a roll of green solid #10 sitting on the clearance aisle of the local Menards for at least two years so it is available to be used by a different breed of hard working mfers.

 

[66slabside]

Good to know, it will be stranded. Thanks for the info

 

[sberry]

I have done a bunch of these, maybe a couple 3 my own and a dozen for others. I have never NEVER had someone come back and tell me they needed bigger and decided to open a powder coat biz in the garden shed.
I wired a bunch of services to garages that would have been fine with a single circuit. Never had one of these call back and wish I would have ran a 10 at that distance. My first mentor was a paranoid about v drop at the expence of a lot of other stuff, really cost me a lot over nothing.
Just put in water for someone on a small well, 180 ft, garden hydrant, it's so tempting to use inch but the 3/4 really flies and will deliver more than the well. Runs it without shutting off , water comes out just like you were standing next to it, didn't run test on it after but it serves it just dandy.

 

[sberry]

We got a long run to a shack, did it way back and used a whole roll of wire. Never welded from it,,,, but the tender put coffee pot, the phones and the cash register on it along with radio, never a second thought.
The nature of the forum promotes overkill, some is ok, some practical but leads to a lot of wire and pipe parked in the ground never utilized. Some at the expense of getting it done in the first place, job could cost a few dollars turns in to 100s for nothing just in case.
This is what I harp about here, working on same stuff, same customers and my own for decades, 1 time I wanted another wire but it took another route anyway and much was obsolete. Ran lots of 1/2 to light fixtures,,, never wished I up sized a pipe so I could add welding wires to it.
As a side note my bud was the master on a new casino build and it was one of those design as we go and build deals, said he up sized every pipe from the start and should have went 2,, ha, said a place sposed to seat 30 in the morning became 300 by afternoon, ha.

 

[sberry]

Seems I added a wire or 2 to a pipe I installed over the years but didn't need a bigger pipe, probably another switch or something but it's so rare I not messing with it and could go back and recover a lot of unused wire if I wanted to. Got 20 circuits in a building I use 2 on occasion. Use 200 watts once in a while and not 20A.

 

[nadogail]

Over Kill is under rated.

I have yet to see a minimum sized installation that did not get more load attached after it was installed.

 

[u2slow]

Ground rods have nothing to do with preventing fault current from create shock potential. The EGC accomplishes that. Also, grounding rods are not for establishing a low impedance fault current pathway. They are for shunting lightning and surges.

Also, ground rods are not required unless there is a subpanel.

Muddy? Minute differences in ground potential causes your dairy cattle to not produce milk. That's why we add ground rods to subpanels in (farm) outbuildings. Otherwise the EGC/ bond wire included with the feeder is sufficient. We have lightning in Canada too. OTOH, maybe its weak like our dollar.

 

[AntonLargiader]

I have yet to see a minimum sized installation that did not get more load attached after it was installed.

Why would you? The owner has no need to complain to anyone...

 

[wyliesdiesels]

Muddy? Minute differences in ground potential causes your dairy cattle to not produce milk. That's why we add ground rods to subpanels in (farm) outbuildings. Otherwise the EGC/ bond wire included with the feeder is sufficient. We have lightning in Canada too. OTOH, maybe its weak like our dollar.

Read what i said again. Grounding electrodes have nothing to do with clearing fault current.

Also The abscence of the requirement to have grounding electrodes for detached stuctures in canada makes no sense.

You dont want the lightning current travelling to another structure to potentially damage other equipment there. You want it shinted at the point of origin to limit damage.

 

[u2slow]

Read what i said again. Grounding electrodes have nothing to do with clearing fault current.

Also The abscence of the requirement to have grounding electrodes for detached stuctures in canada makes no sense.

You dont want the lightning current travelling to another structure to potentially damage other equipment there. You want it shinted at the point of origin to limit damage.

Re-read again. I pointed out the extra rods would maintain better/common earth potential - as required for livestock - optional for other outbuildings. That's what CEC rule 10-208 addresses. The PoCo's pole mounted transformer with ground cable & rod is in good shape to dissipate a lightning strike. Codes are in place for safety, so clearly there's more than one way to do things safely.

 

[wyliesdiesels]

Re-read again. I pointed out the extra rods would maintain better/common earth potential - as required for livestock - optional for other outbuildings. That's what CEC rule 10-208 addresses. The PoCo's pole mounted transformer with ground cable & rod is in good shape to dissipate a lightning strike. Codes are in place for safety, so clearly there's more than one way to do things safely.

as someone who does grounding for motorola and other communication systems, i can tell you that the ground rod at the PoCo pole or another building is not good enough.

And as i said previously, you dont want the strike travelling to other buildings. Relying on the ground rod at the pole means the strike would have to travel through the neutral bus, onto the service neutral and down the pole. Most strikes will take a shorter path and a lot of times this means through equipment and things you dont want fried. Theres numerous examples of this happening on this very group.

 

[66slabside]

I seem to have started quite the fuss!! But it has been an enjoyable read.
Thanks again guys!

 

[sberry]

Just do this, bury a 12 uf cable, it fits it all nicely, is sufficient for most people, is economical. If you want to bury shallow,, 12 inches gfci it before it leaves the structure. Sounds like the guy wants to get rid of the cord he has been using, this is admirable and logical. The cord has likely been lighter than this cable. If you are much over the 150 ft or he intends to weld or run real air compressor then its worth a 10 upgrade, for normal ****, hand tools, some lights its irrelevant. Most likely its idle 99.5% of the time.

 

[theoldwizard1]

Just do this, bury a 12 uf cable, it fits it all nicely, is sufficient for most people, is economical. If you want to bury shallow,, 12 inches gfci it before it leaves the structure. Sounds like the guy wants to get rid of the cord he has been using, this is admirable and logical. The cord has likely been lighter than this cable. If you are much over the 150 ft or he intends to weld or run real air compressor then its worth a 10 upgrade, for normal ****, hand tools, some lights its irrelevant. Most likely its idle 99.5% of the time.

Good for 15A for sure. More than his cords !

 

[alfredeneuman]

Just do this, bury a 12 uf cable,

The load @ 150' would have to be 6 amps or less @ 120v to be under 3% VD.
A horrible circuit design, to be sure

 

[sberry]

So what ? Some days I got to wonder if the internet has made some minds mushy? Nominal is over 120 in most places but I could lose 13V and still be 110. This is for a garden shack. Lots of 100 ft runs in modern houses, no one blinks.
The absolute fear of a little drop has multiplied itself with all the "research" someone can read. The guy has been using a fukkin extension cord.

 

[sberry]

I have done a few tests with some machines. 23A on a welder, 50 ft of 12 cord, 4V loss. Operator cant tell the difference from the wall at the panel. 50 ft of 14, somewhere around 7 or 8 as I recall, machine wide open, highly experienced operator can just tell the difference and needs to touch the setting just a fuzz.
My little compressor, close to the panel snaps the breaker, add 50 ft of 14 and it works, hasn't burned up the motor.

 

[sberry]

I been doing this a long time, cant recall ever having this type of thing not work. This has cost me a lot, I have looked at the charts, ran 4/0 where number 2 would have worked fine. I have ran a lot of long circuits, live on 250 ft of 2 alum, I have NEVER had one where I could tell any difference. Never added a powder coat oven to the garden shed and actually never added any significant load, really the other way, stuff gets used them it goes away, becomes somewhat obsolete, people get older, lights get better, less load.
I remember the first air line I ran a distance, read some charts, come up with the idea of inch, some old timer said,,, 1/2 will work fine. 25 years later ran the same with a 1/2 hose, couldn't tell the difference. I have a 120V 250 ft, I quit thinking about it, everything I plugged in to it worked fine.