extending electrical to the shed

[ChadTower]

One of the things I'd like to do this year if possible is run power from my house to my shed.  It's 10x12, framed and vinyl sided, pretty much a small outbuilding.  Being able to work on games out there rather than in the basement would clear up a lot of room down there... and it would provide power to the yard that would be very useful for parties and such.

Has anyone done this in a similar setup?  The electrical panel is in the basement on the foundation wall facing the shed, which is helpful, and the shed is probably 30-40' from the house.  I'm guessing I'd have to run the extension underground in a pipe and have a subpanel put in in the shed? 

[shardian]

I would like to have lights/outlets in mine, but don't want to go through the effort. It is only a few feet from my side entry door, so I'll just stick with extension cords.

I would like to have a solar light setup though. It is annoying to have to use a flashlight at night.

[CCM]

google goodness...


http://en.allexperts.com/q/Electrical-Wiring-Home-1734/electric-outdoor-shed.htm

http://forum.doityourself.com/electrical-c-d-c/278307-running-electricity-shed.html

http://www.homerepairforum.com/forum/electrical/724-running-electricity-shed.html

http://www.diychatroom.com/f18/running-electric-shed-10824/

[ChadTower]

Nice!  I had read a bunch of similar articles in parallel with making this thread so the requirements are starting to come into focus.  I'm trying to decide now just what capacity I need.  20A or more capacity is a given for power tool reasons... maybe a 240v line too in case I ever want to drop a good tablesaw in there or maybe a spare oven for powdercoating.

[shardian]

I thought you couldn't even replace a receptacle up in that state without an electrician?

[ChadTower]

I thought you couldn't even replace a receptacle up in that state without an electrician?

I can run the wiring and such but can't do the terminations.  I don't need an electrician to dig the trench or run the conduit and that's probably most of the manual work.

[Ed_McCarron]

Make sure the electrician removes the neutral/ground bond screw at the subpanel.  Bonding neutral to ground is verboten in subpanels, and most often that screw is installed from the factory.

[shardian]

I liked the idea in one of those links to use 220 wire to run 2 circuits - with the circuits alternating each plug along the wall and sharing a neutral bus. I have to ask though - is that REALLY code kosher? If I pulled an outlet away from a wall and saw red wiring I would freak out! I had a bad enough problem with the horrible 3-way wiring jobs in my house.

[Ed_McCarron]

I liked the idea in one of those links to use 220 wire to run 2 circuits - with the circuits alternating each plug along the wall and sharing a neutral bus. I have to ask though - is that REALLY code kosher?

Hm.  I was set to say yes, as long as the hot wires weren't white or green.  I've seen black, blue, red, all used as hot.

However, if you have 40A worth of feed (2 20A ckts) and 20A worth of neutral, I'd think thats cause for concern.

I'd avoid it.  You'd be fine unless you started maxing out circuits, but I wouldn't want to have to explain it to the insurance inspector.

[MonMotha]

Note that I'm not an electrician and not by any means an expert on the NEC or local electrical codes.  Electrical codes often have little to do with electrical reality.

If you have a 240V split-phase setup (as is common in US residential installations), you can run "40A worth" of 120V receptacles using only "20A worth" of neutral quite easily.  The neutral only has to carry the difference in current between the two split phases.  So, worst case, you're drawing 20A off one line and zero off the other, so you end up with 20A on the neutral.  If you load both phases evenly (resistive loads), you actually end up with the neutral carrying nothing: the current travels from one hot line, through the loads, to the other without ever needing to use the neutral.

You take advantage of this when running power into your home.  There are three equal size lines running from the utility company transformer to your main panel.   L1, L2, Neutral.  Your panel then splits things up to that every other breaker is on the same phase.  That's why 240V breakers are twice as big: it has to hit both phases.

[DaOld Man]

I built a 12X16 shed about 6 years ago.
I wanted enough juice out there in case I decided to use a small welder (which I havent yet).
anyway, Its about 80 feet from the back of the house.
For power I ran 4 #6 AWG. Two hots, a neutral and a ground. I installed a 8 circuit breaker panel with a 50 amp double pole main breaker.
I ran 1 inch PVC buried in the ground for the power.
I also ran 2 3/4 inch conduits, 1 for telephone and Cat 5E lan cables, and another with 10 #12 spares.
The spares worked out pretty good, just in case I ever want to add something else the hard part is done. I did use 3 of the spares and mounted a switch by my back door that turns on a flood light mounted to the outside front of the shed. This lights up most of the backyard, and I tell you it has really been worth the extra cost. I can turn on/off  the flood lights from the house or from the shed.
My local code also required that I run the separate ground to the shed, and not bond ground to neutral just like Ed McCarron suggested.
I also attached the ground to the metal siding of the shed, and buried a 8 foot ground rod at the shed.
It seemed like overkill at the time, but you gotta do what you gotta do, plus I have not had lightning run in on anything since I did that.
I buried the PVC conduits about 18 inches in the ground, entered the house through the foundation blocks. I poured ready mix cement around the entry point to keep out varmints.
It all looks real good, no exposed wires between house and shed, so no worries about ice or tree limbs.
I wired two GFI plug circuits in the shed, plus fluorescent lights, and the flood lights.
I still have 3 spare spaces in the breaker panel, so if I break down and buy a small welder some day, it wont be hard at all to wire in.
Did all the work myself so i know it's right.
Good luck on your build, extra space is always a great thing to have.

[Ed_McCarron]

If you have a 240V split-phase setup (as is common in US residential installations), you can run "40A worth" of 120V receptacles using only "20A worth" of neutral quite easily.  The neutral only has to carry the difference in current between the two split phases.  So, worst case, you're drawing 20A off one line and zero off the other, so you end up with 20A on the neutral.  If you load both phases evenly (resistive loads), you actually end up with the neutral carrying nothing: the current travels from one hot line, through the loads, to the other without ever needing to use the neutral.

Makes sense I guess.  Stick a hypothetical 20A lightbulb on each leg and it works out.  Just seems odd.

This is why I do control work and not residential wiring.

[shardian]

As with most people, I know just enough about wiring to be dangerous. 

[ChadTower]

As with most people, I know just enough about wiring to be dangerous. 

Same here.  I have no idea what a phase is.

[Ed_McCarron]

As with most people, I know just enough about wiring to be dangerous. 

Same here.  I have no idea what a phase is.

Oh, serious?

Your 240v power is really two 120v lines, 180 degrees out of phase with each other.  From either line to neutral/gnd, you get 120.  From line to line you get 240.

Switch to industrial apps and 480v/three phase becomes common.

[DaOld Man]

You dont really have to know what a phase is, just if you want 220 volts at the shed, run 4 wires. If you just want 120 volts, then 3 wires will do the trick.
But I highly suggest you run for 220 volts, it's a lot easier to do that now than it will be later, plus it makes your property worth more, or at least more eye-pleasing when and if you decide to sell.

My only regret with my shed is that i should have made it bigger.
Space tends to fill up quick, plus I keep my mowers out there, so when I work on a project, I have to pull the riding and push mower out into the yard.
If I ever build another I will add extra footage to my plan, for sure.

[ChadTower]

My only regret with my shed is that i should have made it bigger.
Space tends to fill up quick, plus I keep my mowers out there, so when I work on a project, I have to pull the riding and push mower out into the yard.
If I ever build another I will add extra footage to my plan, for sure.

Same here... lawnmowers taken out to work on stuff and all.  I had mine built 10x12 because that is the largest size for which I did not need a permit.  The building inspector spent 6 months dicking me around about the property line not being exact enough and wouldn't permit the shed without a survey... and every survey company I called wanted $1500 to survey the line on a quarter acre property.  That was during the tail end of the construction boom.  I bet I could get someone out to do it now for a case of beer and some sandwiches.

[shardian]

Being in an established neighborhood, shouldn't your property have survey spikes? I went to the courthouse and got the original survey of my subdivision. Turns out all 4 corners of my property have spikes. I located all 4 of them one day with a metal detector. I then put big sticks in the ground on 2 of them to remind my dumb ---smurfette--- neighbor that she DOES NOT own all the way up to my side porch. You kill my tree you die, ---smurfette---! 

[ChadTower]

Being in an established neighborhood, shouldn't your property have survey spikes?

Granite posts planted in the '50s and we couldn't find them without tearing out mature landscaping on one end and maybe part of the sidewalk on the other.  Consensus among the original owners left (and that's much of this street - old folks) is that the markers could be way underground by now since no one seems to be able to find them.

[ChadTower]

I have an electrician coming in tomorrow morning to scope out the job and advise me on what path to trench.  I'm going to get that taken care of before he comes in to do the panel work.  Now is the time, I guess, to decide if I want to put in a line capable of a 240v outlet or if I just want to run a string for now so we can pull another line in the future.

The most immediate possibility I see for a 240v outlet there is for an old electric oven to powdercoat.  Do they make 120v ovens, though?  Can't say I know if I could get by with 120v for an old oven.

[whammoed]

Ron Richardson: Yeah? Are you gonna make it all 220?
Chad Tower: Yeah. 220... 221, whatever it takes.

[ChadTower]

 

[youtube]http://www.youtube.com/watch?v=28Y3tmxJF6w[/youtube]

[JeepMonkey]

You could take a 240V breaker from the house panel to feed a small distribution panel inside the shed.  At the shed distribution panel you could have both 240V and 120V breakers to run whatever curcuits you want.

The cost difference between running a 240V and a 120V should be very small.  Run a 240V curcuit out there, you will eventually have something in the shed that needs it.

[whammoed]

It's ironic how Ron thought he was being the smart one, but the standard has been 240, not 220 since the 70's
Gonna have to watch that movie again...think we have it on DVD

[shardian]

It's ironic how Ron thought he was being the smart one, but the standard has been 240, not 220 since the 70's
Gonna have to watch that movie again...think we have it on DVD

Let's get real technical and call it 115/230, since that is what is always actually flowing in the house.

[whammoed]

It's ironic how Ron thought he was being the smart one, but the standard has been 240, not 220 since the 70's
Gonna have to watch that movie again...think we have it on DVD

Let's get real technical and call it 115/230, since that is what is always actually flowing in the house.

Says who?  Last time I measured my house was at 126/252.  Had to buy a buck booster for the wife's tanning bed.
120/240 is the standard...i think maybe 117/234 is the average maybe?  I think it's ok to be off by 5%?

[MonMotha]

I've always wanted a place that surveys average "wall voltages" across the US.  It'll vary by neighborhood and even individual home.  Heck, it'll vary based upon what you've got turned on due to voltage drop across the feed going from the utility company's transformer to your house.

120V is generally accepted by designers to be the current "standard" in the USA.  The standard US voltage has been creeping up over the past 50 years or so.  I guess it's been determined to be infeasible to upgrade everybody to 240V, so they just keep creeping what we have up, allowing the design targets to shift over the years.  Hence, it's not uncommon to see 117V (the accepted "standard" about 15-20 years ago), 115V (~20-30 years ago), 112-113V (~30-40 years ago), or 110V (about 50 years ago) depending on the age of the service equipment (NOT necessarily dwelling age).  Generally, designers expect at LEAST 5% variability and usually try to make it run off as wide of a range as they can.

Many electronics are designed for 100-120V range as 100V is line spec in Japan.  Note that Japan uses wall plugs compatible with those used in the USA, though the third prong (earth ground) is very uncommon and even polarized outlets are only present in relatively new structures.

I gather you guys in Europe managed to standardize on 230V throughout the EU, including the UK which had to actually reduce their line voltage (which was up to like 237 or something before that standard was adopted).


If your residence is running unusually high (>125V) and it concerns you, you can usually get your utility to knock it down some.  The transformers at the street that feed residences (usually one or two) have several output taps to facilitate this.  Just call up and say you noticed that light bulbs were burning out quickly and the voltage measures high.  Don't be surprised if they overcorrect slightly and knock you down to 115-117V.

Same if it's running really low (<110V).  Call up and note that you are experience more noticeable than normal light flicker when your air conditioner turns on.  Again, don't be surprised to end up with 120-125V if they do something.


FWIW, my house measures 121V (just measured with my assuredly accurate $5 multimeter) on an unloaded circuit with no major appliances running.  It'll drop down to ~117V with lots of stuff in the house turned on or as low as 113-115V on a 15A circuit (AWG14) at near full load (e.g. vacuum cleaner or space heater).  My friend's house in another city tends to run a little higher at ~123-125V unloaded.

Both of us have tons of stuff from Japan (stamped 100V); it all runs just fine.  SMPS based designs frankly couldn't care in most cases, and most transformer based devices can tolerate some variability as it is expected in the design.


As for wiring your shed, I say spend the money to run a nice beefy (like AWG10) line with three conductors (plus ground, of course) to your shed.  Put a sub-panel in your shed, and then you can run whatever you like.  AWG10 should allow a 30A or maybe 40A panel (240V, of course, so 60-80A worth of 120V circuits).  Consult all relevant codes, of course (I am not an electrician, and your local codes may vary, anyway).  A sub-panel makes it easy to expand in case you want that oven, a welder, a large air compressor, etc.

If you want to go really big, mobile home feeder can be a relatively inexpensive medium to move a lot of juice, but it's often aluminum, not copper, so again consult all relevant codes regarding its use.  Mobile home feeder is sometimes rated for direct burial, which can save you a conduit.

[ChadTower]

Awesome post, thanks.  I think a 30-40A should be just fine, really.  It's a 10x12 shed and the biggest thing I could see ever being out there is a cabinet tablesaw.  I have to keep in mind that it's on the same main panel as the house and my service is only 100A.

[ChadTower]

Electrical inspector has noshowed twice now to inspect the trench... just waiting for that so I can fill it back in.

[Ed_McCarron]

Do you have any soil mixed in with your rocks?

[shardian]

Do you have any soil mixed in with your rocks?

I go though the same crap whenever I dig holes. Lots and lots of scrap fill material to build up the land here I suppose.

as for those roots...I bet that took FOREVER to dig that trench and leave the roots intact. Screw that!

[ChadTower]

Do you have any soil mixed in with your rocks?

No kidding, and what isn't clear is the amount of roots, too.  There are more than visible in the pic.

shardian, you're not kidding about the roots, but I did cut some of them.  I like those trees, though, so I saved as many as I could.

[NIVO]

nice moat........now come out swinging in your armor 

[Zakk]

You'd think you wouldn't have to have all those bikes just hanging out on the lawn...what with there being a shed and all.  Or were those ridden by all the migrant workers you used for the trench?

[ChadTower]

You'd think you wouldn't have to have all those bikes just hanging out on the lawn...what with there being a shed and all.  Or were those ridden by all the migrant workers you used for the trench?

 

That's way in the back where it's not too visible from the street.  I am keeping the shed interior perimeter clear until saturday when the electrician comes to finish the job - it will have outlets on all walls.  A lot of that stuff is back in the shed now, though.  I'm not that worried about the bikes that are still out. If someone were to come around the side of the house to steal a couple of 20 year old Huffy mountain bikes they'd probably be doing me a favor. 

Only one person has commented (outside this thread) on the Star Wars sitting right inside the door... I figured that would get a joke or two before the bikes did.     And not one joke about the MDF against the tree!   

[Zakk]

Even Cheffo has let the MDF jokes go. 

[Ed_McCarron]

And not one joke about the MDF against the tree!   

I was biting my tongue...

[shardian]

Only one person has commented (outside this thread) on the Star Wars sitting right inside the door... I figured that would get a joke or two before the bikes did.     And not one joke about the MDF against the tree!   

I don't have the patience (or the oddness) to analyze anyone's photos to the degree.

[shmokes]

Chad, are you one of those people who nonsensically turns a camera diagonal before taking a picture, to get an artistic shot?   

[ChadTower]

Chad, are you one of those people who nonsensically turns a camera diagonal before taking a picture, to get an artistic shot?   

No, I was trying to get as much of the length of the trench as possible... I was actually standing right up against the side of the house on the pile of dirt.  When I took it from the other side the sun was way too strong and the photo was totally washed out.