Wiring pole barn

wolc123 · Jul 8, 2021

I hope to get my pole barn wired this winter. I ran 2" PVC conduit to it during construction, in anticipation of future needs. I have been getting by ok with a single direct-bury, 15 amp wire that my grandad ran to the previous barn, that was on the same site.

With modern LED lighting, that single 15 amp circuit has been working ok, but running everything on extension cords is getting old. My plan is to use 1" gray PVC conduit for a "proper" job of the interior wiring. I have a bunch of that, which an ill informed maintenence man used for air lines at a former employers shop. That didn't pan out, because it kept blowing out. I have hundreds of feet of that 1 inch gray PVC, and boxes of fittings for it.

It looks like there is lots of reasonably priced electrical boxes, etc for that 1 inch PVC at Home Depot. What kind of wire should I use ?

When and if I ever need more power out there (for a big compressor or welder or something), I will run more power thru the 2 inch conduit from the 200 amp service in the house.

jpolcyn · Jul 8, 2021

If running in conduit THHN is what i would be using. If you go with 110v 20amp circuits go the extra mile and get 12ga wire size. just my .02 cents.

EddieWalker · Jul 8, 2021

First thing you need to do is create a sub panel inside the barn. You have to decide how much power you want to pull from your main panel and buy the correct sized wire to do this. Since you might be new to this type of work, you might want to hire somebody to do this for you.

Once you get power to the sub panel, then you have to figure out how many 220 outlets you want. Usually one for a welder is enough, but if you never plan on welding, you don't really have to have a 220 outlet.

For your wall outlets, 20 amps is better then 15. Most tools will run fine on 15 amps, but a few will use all of that 15 amps and you might start tripping breakers when you get really busy in there. I only use 20 amp lines for my outlets. 20 amps means 12 gauge wire.

For you lights, you want to run them on their own breaker. 15 amps is plenty for lights, especially LED's. It's easier and cheaper to use 14 gauge wire, so that's what I always use for lights.

You are not supposed to run Romex through conduit. I do it anyway. Mostly I run my wires through the walls and then cover up the walls with plywood or OSB, so you don't need conduit. But when the wires are exposed, like going up to to the lights, I put my romex inside conduit.

grsthegreat · Jul 8, 2021

Actually you can run romex in conduit as long as the conduit is indoors and your using the conduit to give physical protection to the romex.

what we do here in idaho on pole barns Is staple romex on horizontal runs 8 foot and higher above ground level. Wire leaving subpanel is installed in conduit up to 8 feet from ground level.
when wires drop down to outlets, they enter conduit at 8 feet up then run inside conduit to a steel outlet box.

this method is approved here whenever walls remain open. If the walls are to be sealed in plywood or drywall then we just wire like you would a house.

Doofy · Jul 8, 2021

You will be better off running all your wiring in the 2" conduit at the same time. Easier pulling.

jthibodeau89 · Jul 8, 2021

If you have a 2" conduit already burried, you are good for a 150A service. I used 2-2-2-4 service wire in 1 1/2" conduit to run the 100A service to our barn. A couple out buildings were run from a 60A breaker in the barn with #6 THHN in 1" PVC conduit.

I use armored MC or BX cable in the barns and out buildings for all the 15A and 20A circuits. It is impervious to rodents, and cheaper than conduit. Circuits that are 30A or greater are run in conduit.

Key point is that all sub panels must NOT have the ground bonded to the neutral leg. The ground must be separate back to the main panel and an earth ground rod should be provided at each exterior sub panel.

nyone · Jul 8, 2021

Right now with today's wire prices I may just get the pannel and service working in the barn and hold off on the real wireing until wire prices drop. They will but not over night and you have been useing the building as it sits.

wolc123 · Jul 9, 2021

I buried the 2" conduit in 2019, when I was doing the site work. It was cheap back then. At this point, it is there for "future needs". When and if I retire from my day job, I might have time for some bigger projects / equipment out there, that will require more power than the single, direct bury cable on a 15 amp breaker that feeds the pole barn now.

The sub panel will also have to wait until that time. Currently, there are only (3), 4 ft LED lights, and a garage door opener/light out there. I have yet to trip that 15 amp breaker with all of those on, while running a 3/4 hp band saw and a 2 hp shop vac. My small 110 volt air compressor and buzz box welder also work well on it. The guys putting up the 36 ft x 50 ft pole barn shell did trip that breaker a few times while running their larger saws and stuff though. LED lights have been the biggest game changer in pole barn power requirements.

This winter, I will probably pick up some 12 gauge wire for outlets, and some 14 gauge for the lights. Then I can do away with the extension cords. I will run that wire thru the 1" grey PVC conduit, which I have in almost limitless supply. I just need to buy the required hangers and boxes and that stuff still looks cheap at Home Depot.

wolc123 · Jul 9, 2021

Here are some photos of the current situation, which I hope to rectify somewhat this winter. Note that the direct bury wire to the corner outlet to the barn from the house is 12 gauge, as is the extension cord that feeds the main outlet inside the barn.

The power strip is plugged into that and is only turned on when I am in there. It feeds the 14 gauge extension cords to various tools and 3 LED lights. The garage door opener is plugged into a 14 gauge extension cord which also goes to the main outlet. I unplug that when I need the air compressor.

My plan for this winter, is to do away with the power strip, install some outlets where needed, a few more light fixtures, and some switches for the lights. The past two years, wired as shown/described have indicated that my current 15 amp power supply is adequate. I just want to make it a little more convenient.