Installing Electric To The Barn

MossRoad · Jan 24, 2003

If you decide to only run one circuit out there like it sounds, you can put X10 appliance outlets and light switches in some of the boxes. These can be controlled by several different types of remotes from your house or garage. They send signals over your power lines. Each module is addressable. That way, you wouldn't have to run extra wires. So, you could control the lights from the garage or the house, or a keychain remote without any special wiring. I use one to run my pool pump all summer. It works great.

Phred · Jan 24, 2003

interesting timing on your question.

I have a well that I ran wire to ~300 feet from the house. Being a cheapo I looked at the wire sizes and did the calculations and said sure 10 /3 UF will be more than enough for what I need........ Wrong.
One year latter and I need more juice for a new load. Maybe could get by with the 10 gauge but it would be close. The voltage drop would probably reduce the pump life.

The good news is I had the presense of mind to run the UF in conduit. So rather than dig up the 300 feet of wire I will be pulling an additional 8/3 UF through.

But it will be a pain in the ^$$. So this weekend I will be trying to pull that 8/3 UF through the conduit and thinking of all that money I saved using 10/3 rather than 8/3.......
but of course now I will have paid for the 10/3 and the 8/3!

Moral of the story, Figure out what you need in power. Multiply by at least 3 and then run it in one size conduit larger than the specs call for. You will be glad latter on.
Why the bigger conduit than the specs call for? Ever try to pull 8/3 or bigger through a conduit for a few hundred feet? Time for the tow truck or logging winch...
Also watch the number of 90s. More than 2-3 90s and you will likely be digging it up again any way.

Fred

NY_Yankees_Fan · Jan 25, 2003

If you decide to only run one circuit out there like it sounds, you can put X10 appliance outlets and light switches in some of the boxes. These can be controlled by several different types of remotes from your house or garage.

Moss,

Where did you get the units at, and how much?

Thanks

Tom

MossRoad · Jan 25, 2003

I got mine at x10.com and smarthome.com. I have lots of that stuff around my house. A heavy duty X10 110v 20AMP outlet is about $50.00. Incandescent light switches in bulk for $6 or $7, singley, $8 or $9. A simple table top controller that plugs into a wall outlet back in your house is about $10. That would get you going.

You could get more elaborate with timers, controllers, computer control, etc..., but that might be a discussion for another thread. There's one over at CountryByNet. <A target="_blank" HREF=http://www.countrybynet.com/forums/showflat.php?Cat=&Board=fix&Number=7013&page=0&view=collapsed&sb=5&o=&fpart=1>If you're interested, click here.</A>

Crazykansasan · Jan 26, 2003

I'm confused? Why did you run UF in conduit. It is my understanding that UF is underground feeder and is made for direct burial. I've been told that placing UF or MN in conduit prevents heat dissipatation and may cause wire failure.

Phred · Jan 26, 2003

Did not need to its overkill. Your right it is designed for direct burial.
Started with the UF and decided to run the conduit once I had the wire already.
My understanding, (not a wire expert), is that the main difference between UF and THHN or romex is the insulation is thicker and UV resistant.
If you look at a section of UF the insulation is much thicker than THHN.

How could it cause over heating? For a long run like this the resistance per unit length is small for the current used. The reason you use a larger wire is to prevent a large voltage drop. So the heat generated per unit length is very small.

For example a 1 HP (220-240V) well pump could be run off 12 gauge for a short run. However, at 500 ft from the source 10 gauge is needed so the voltage at the pump is not dropped to much. But heating in any section of the wire is very small, lets do the math:

10 gauge wire has a resistance per 1000' of 1.018 ohms.
So our 500 foot case would be 0.509 ohms.
Lets assume that 1hp pump actually consumes 1200 watts due to power factor, etc... rather than an optimistic ~700 watts. The voltage drop along the wire would be about 5 volts for this case.
Power loss in the wire is then on the order of 12 watts. For the entire 1000 feet (500 feet down and then back).
A 12 watt heater over the length would not even be noticed no matter how good the insulation is ....IMHO.

Fred

Phred · Jan 26, 2003

Update.

Turned out not to be as painfull as I had thought.
Key was the conduit and the fact that I up sized it a bit.

For #8 most charts will indicate ~1" conduit would be adequate.
I ran 1 1/2". Cost was not much more and it made pulling out the old 10 gauge UF and swaping it with 8 (THHN this time) pretty straight forward.
A little bit of friction multiplied by a couple hundred feet and a few 90s makes for a work out.

Anonymous Poster · Jan 27, 2003

The only difference between THHN and say MTW is the THHN has a coating of teflon on the outside. MTW and THHN are both rated at 90degC

djradz · Jan 27, 2003

Hey Kevin, Engineer by day, homeowner by night! /w3tcompact/icons/grin.gif/w3tcompact/icons/grin.gif Actually, I work for the local electic utility and we direct bury all the time. Feeds from transformer pole to customer, underground distribution circuits, and circuits in substations. You just need to try to be sure to minimize the rocks. Even at that, we put plenty of circuits in gravelly locations. I just think in this case I'd spend the money to double the size of the circuit or install a second or third circuit, rather than installing conduit that I won't be able to ever pull anything else through again anyway.

Inspector507 · Jan 27, 2003

Ray,
MTW is not recognized as a suitable conductor for the run of the mill wiring to the barn in conduit. It is Machine Tool Wire. They both could have a nylon coating which would make them 90-C.
I can tell you what I would run, if I were doing it.
Run 1 1\4-1 1\2 inch PVC 18-24" deep. Pull 4#6 THHN conductors, hit a sub-panel and call it a day. If you feel the #6's are not enough in the future, you should be able to pull them out and larger ones in. But that's just what I would do.

Jerry (27 years in the trade, 14 inspecting)

Anonymous Poster · Jan 27, 2003

I wasn't suggesting that MTW should be run. I was only stating the difference in MTW and THHN. I use both at work in there respective places. I myself ran 4-#3 THHN in 2in PVC conduit for 100A service into a sub-panel.

Ray (10yrs. industrial electrician)

kcbarnes · Jan 27, 2003

Can I ask is it consumers energy or one of the "BPU's"?

Pks · Jan 27, 2003

RayS,

I don't quite follow the statement: "...wire size for 50 amps shall be no smaller than 6Awg (55A)" Is this statement for the context of a supply/feeder run as opposed to a branch circuit?

My electric drier uses 10/3-wg on a 30 Amp 230v circuit breaker. And my welder manual (which is not yet installed) is requesting 10/3-wg 230v 100 Amp breaker, if the run from the box is less than 87 feet.

Anonymous Poster · Jan 27, 2003

Had to jump in on this, One thing not mentioned is rodents, with the wire direct buried the gophers think its some juicy root and gnaw on it and cause it to leak to ground, or just plain blow up wire and themself. I have had this happen 3 times on an 1100' run to my well, very tough to trace out. I wish I had put it in conduit now, but at the time I thought it was ok 2' deep. Also what is important in sizeing the wire is the voltage drop, it should be 3% or the wire will overheat, for long runs the resistance of the wire must be taken into account. to get 20amps at the end of 200' run without overheating wire you would need to use #6 thhn, for 50amps #2 both copper. also running romex in conduit is a no no because of the overheating. Motors can run on a higher voltage drop because of there intermitent use,3% voltage drop is for general purpose,lighting loads. A 50amp sub is the way to go most of the time,compressors,welders,saws,etc. Also very cheap ($15 home depot) considering time and effort

bky · Jan 27, 2003

I would agree with inspector057run pipe in the ground (pvc is cheep) also your allowed 360dirgrees in bends before you have to hit a pulling point.
Also it doesn’t matter if the wire is rated at 90 degrees because most connections are rated at 75 degrees
I seen more wire burnt up or broken in the ground than I care to have seen and had to dig it up to fix.
Pipe is the only way to go.
Also I think they should change the code to reflect that. Just my option

MossRoad · Jan 27, 2003

You might be allowed 360 degrees in bends, but chances are you aren't gonna be able to pull it over 270 degrees, even with pulling lube.

Inspector507 · Jan 29, 2003

With the right size pipe, and the right amount of wire lube, you'd be surprised at what we've pulled.

MossRoad · Jan 29, 2003

I agree with you completely, however, the right size pipe, and the right amount of wire lube are two things most people don't use... /w3tcompact/icons/laugh.gif

Wingnut · Jan 29, 2003

I agree with you completely, however, the right size pipe, and the right amount of wire lube are two things most people don't use... 
especially since the right size pipe is the next larger pipe than you used and the right amount of wire lube is about a gallon more than you have available
/w3tcompact/icons/laugh.gif /w3tcompact/icons/laugh.gif

MossRoad · Jan 29, 2003

especially since the right size pipe is the next larger pipe than you used and the right amount of wire lube is about a gallon more than you have available

You got that sooo right! /w3tcompact/icons/laugh.gif