Electrical Advice

[trkbldr]

I built a pole barn last year on a lot that I plan on building a new home on in the spring. I want to install a short run of the gray PVC conduit underground from the barn toward the home site so I can landscape around the barn and not have to disturb it later. The electrical needs for the barn will be minimal. Basic lighting (6 to 8 flourescents), and 6 to 8 outlets. I assume the best way to get power there is with a sub panel from the main panel. Now the questions. What size sub panel do I need? Will a 60 or 75 amp be sufficient? What size wire will I need to run from the house to the barn? The distance will be around 100 feet. This leads up to my main question at the moment - what size conduit will I need to handle the wire size required? I really don't want to bury it and find out later that it is too small. I greatly appreciate any and all replys.

 

[Spark_man]

I ran a 100 amp circuit and panel from my house to the barn I built. I figured, better to have 100 and only need 50 than to have 60 and need 70 - my welder runs off of a 50 amp breaker and the compressor off a 30. The cost difference between a 60 and 100 amp panel wasn't that much. I used underground rated cable rather than burying conduit the whole length. I just used conduit where the cable enters the buildings. Don't forget to get a grounding rod!

 

[EddieWalker]

I would really reconsider your needs for putting anything in right now. I know you want to start landscaping, but when you build your house, it will get all tore up anyway. Putting in an underground line wont do much damage to the ground when you do it, and anything that is disturbed will just grow back in a month or two anyway.

I've found that house plans keep changing until you pour the foundation. Even then, there will be some more changes. It's all part of the process. The more you learn, the more ideas you have and the more likely you are to make modifications to your plans. Don't limit yourself to anything by starting on too many projects now. Wait until the house is under construction, then when the utilities are going in, you can add the power line to your barn real easy.

There are house panels designed for sub panels. They have extra lugs in them that you use to run your wire to the sub panel. Just make sure it's what you get when you build your house.

Usually the main panel is in the garage, but it could be diferent in your situation. Even if it is in your garage, the exact location might change from what you expect it to be right now. Running conduit to that location today, might be a total waste of time and limit your options down the road.

I've met clients that wanted something done that didn't make any sense because of what they had planned years before. Like putting a water line in a location that turned out to be the wrong spot. For whatever reason, they never thought to re-route the water line and put there refrigerator where they really wanted it.

Good luck,
Eddie

 

[dooleysm]

Good advice from Eddie, as usual, but I can try to answer some of your specific questions, if you decide to go ahead or want to be prepared later...

I wouldn't go with anything smaller than a 100 amp sub panel. I don't really know costs, as my in-laws own a construction supply house, so I just get what I need and they tack it on to my account. I can't imagine there's a big enough difference in cost between the supplies you need for 60 amp versus 100 amp service to make it cost prohibitive.

The run from the subpanel in my basement to the barn was just a tad under 100 feet. I ran 2 inch pvc. I ran my electric through the pvc and direct bury phone line in the same trench. I was told there would be interference in the phone line if I ran a line in the same pvc as the electric.

I ran 2 #2 insulated copper for the hot (for 220 service for welders and such, you'll only need 1 if you just want 110), 1 #3 insulated copper for the neutral, and 1 #4 bare copper for ground. I did not install a ground rod at the barn. My electrician recommended, but did not require it. I may add it some day.

Back to your conduit, make sure you get 'sweeping 90's' or whatever they are called, for your bends up into the barn and into the house, if they are needed. If you just plop a regular 90 on there, you won't be able to pull your wire through.

The 2" pipe I ran held the wires I described above, and a run of 12-3 insulated wire that I use to control the floodlights on my house from my barn. I also have planned to add floodlights on the barn, controlled from the house and barn, but haven't gotten around to it. Make sure you leave a string through your conduit after you are done in case you want to pull another wire through later.

Any more questions, just ask. I've just done what you are doing, so I can tell you exactly what NOT to do. I may be less helpful with what you SHOULD do.

 

[Tom_Veatch]

...
I ran 2 #2 insulated copper for the hot (for 220 service for welders and such, you'll only need 1 if you just want 110), 1 #3 insulated copper for the neutral
...

Just one comment - If you only run one hot wire, the neutral will always carry the same amperage as the hot wire and must be the same gauge. Also, only half the breaker positions in the barn panel will be usable. If you run both phases, two hot wires, not only will you have 240v available, but you can "balance" the circuits - i.e. lights fed by one phase, sockets by the other phase - and the neutral only carries the difference in amperage between the two phases.

For example, if at any one time, one hot wire is carrying 40 amps, and the other is carrying 50 amps , the neutral is only carrying 10 amps. Because of that, I believe the NEC allows the neutral to be 1 gauge smaller than the hots in a 2 phase 240v service - especially if there are significant 240v loads on the line. But, don't take that code interpretation to the bank until a real electrician signs off on it.

 

[LarryD]

The posts here have me confused. Is your service going to be on the shop and you want to install conduit for a future home site (TBD).

If that's the case, Eddie is right about a feed through panel but check local code for a disconnect means (breaker) that may be required at the service entrance panel.

You could certainly make a short run away from the shop in the general vicinity of the future house and avoid any digging in a drive/landscaped area.

I would put a 100 amp service in the shop and plan for a 200 amp service in the house. The code only allows 360° in bends for a run so keep that in mind as well as ease of pull for conductors. The bigger the conduit, the easier the pull.

And as long as you have a trench open, put in a smaller conduit for cable/telephone/ security requirements later on. I always run one conduit for my needs and one for my wants, you never know what you're gonna want.