I have an old farm house with 3 out buildings. The main house has electrical service. One out building has a circuit panel that then feeds to an out building and a barn. The out building with a circuit panel used to have separate electrical service but does not any longer. I would like to run a feeder line from the main house to the outbuilding circuit panel which would then provide power to the barn and additional out building. the distance between the two circuit panels is approximately 120'. there is a standard indoor line that runs most of the way. Can these two boxes be tied together at all? With the standard 12/2 line that is in place? What I would be running off this line is basically lights in the barn and 2-3 computers plus a space heater in the outbuilding.Any ideas?
8, either 2 or 3 depending on how you plan to wire it, not 12, should be used on a 40 amp like that. 120' shouldn't be an issue for what you are proposing.
There are no code limits on general use receptacles on a circuit, however, you want to try to anticipate potential heavy loads that may be on that circuit all at one time. If you're turning them into bedrooms, you can generally put two bedrooms on a 15amp circuit because the biggest load you'll ever plug in is a vacuum cleaner. If you're only doing two rooms, you'll want at least two circuits just for good measure, not necessarily a code requirement. If window AC units are anticipated (unlikely in a basement, I know) then you'll want a 20amp dedicated circuit for each AC unit. Window ACs draw a lot of amps, and if you have a dedicated circuit for each window AC you could turn that run into a 240v circuit should you purchase a 240v AC. If you're just putting in one ceiling fixture in each room, then the lighting can be on the receptacle circuits. However, if you were going to be putting a whole bunch of recessed fixture (I would if it were me) you can only load a circuit up to 80% because lighting fixtures are considered constant use. So if you figure out the amps that your fixture will draw (figure with the largest wattage bulb installed in the fixture, even if you're not going to use the max wattage bulb) you can only put 12 amps on a 15amp breaker and 16 amps on a 20 amp breaker. Also, for general use receptacles and general lighting we normally run 14 gauge wire since it's easier to pull and work with. 12 gauge is generally for where you know you'll have a heavy load. These days with computers, LED tvs, and cfl and led lighting, peoples homes are drawing less and less energy, in general. You definitely should consider a dedicated 20amp circuit for if you're going to be using space heaters, sump pumps, dehumidifiers, etc.
The 12/2 is not large enough to handle what you want to run in the remote locations. Start from the main panel and install a sub panel in there with room for 6 circuits. Feed the sub with a 50 amp circuit from the main panel and then run a new circuit to each of the out buildings. A 40 or 50 amp circuit to each will give enough power without the nuisance tripping that the 12/2 will develop. At each of the out buildings install a new 4 or 6 circuit panel. A direct burial cable is easy to install just dig more than 3 feet deep. Overhead means trees and equipment may damage the cables. For the direct burial cable run wire that is rated for 50 amps, use a 40 amp breaker to feed them. Trying to salvage the old installation is not worth the time or trouble. Contact a local qualified professional electrician to do the work. This would be much faster and then it will be done to current code specifications.
