I replaced a barn that had buried 50 amp service from the main house electrical. Before the old building was demoed, I removed the breaker box. I know it needs to be regrounded, as the old building was. That part is easy. What I need need to know is how to reconnect the breaker box removed from the old building to the wires safely. Three wires and a ground. Wire nuts aren’t going to cut it. How do you spice 1/4”+ solid copper wires?
Electrical – Reconnecting 50 amp service to outbuilding
electrical
Related Solutions
To identify the wire gauge, the best way might be to take the cover off of the breaker box (advise to do this with power off for safety, but power can be left on - proceed at your own risk) and see if there are any indications on the wire sheathing. If there isn't, use a guide like to identify the gauge of wire.
As for copper vs. aluminum wire, aluminum might be cheaper in larger sizes. However, aluminum requires some special anti-oxident joint compound when you make connections with aluminum wire (see Ideal no-alox for an example of this stuff). If you don't use the compound, its possible that the connections will fail over time.
EDIT: Using the info you provided in the comments, and the wire voltage drop calculator at http://www.southwire.com/support/voltage-drop-calculator.htm, assuming:
- Single Phase 240V
- Direct Burial
- no more than 3% voltage drop
- 2 AWG aluminum wire
Your wire gauge will allow you to maximum run somewhere in the 75-80 amp range. I wouldn't go all the way to 100 amps, but 60 amp service should work. You'll need 1 AWG wire to run 100 amps safely that distance.
Sometimes panel manufacturers will have a null breaker slot on top, bottom, and/or both. Even though a double breaker seemingly fits right in like it's supposed to, only one phase will be hot.
A visual inspection of the busbar is one way to tell, or if you have the busbar layout diagram it will show too.
In case this is the problem, simply move the double pole breaker into the proper slot, then put a blank slot filler to cover the exposed parts. If you don't have a blank handy a breaker with nothing on it is fine too.
Best Answer
You'll need a pull box and some insulated mechanical ("Polaris") connectors for this
You are correct that wire nuts and an ordinary junction box won't cut it here. Instead, what you need is a correctly sized(6" by 6" minimum unless you have fatter conduit than 1", which will require you to go up to 9" by 9") pull box rated for the environment (NEMA 1 for inside, NEMA 3R for outside) to house the splices, and then insulated mechanical connectors (Polaris/Unitap/...) rated for the gauge of wire in question to make the splices. You'll also need to use a torque wrench to make up the connections -- we're talking torques on the order of 10-20 ft-lbs here. Last but not least, you cannot bury the box -- it must remain accessible so that the next bloke who needs to mess with those splices can go in and do so without having to demo part of the building on a junction-box hunt.