We have a small a-frame cottage in our yard. It has no electricity now but used to have its own meter and panel and was fed by its own power line. Part of the reason for this, I believe, is that there are two old electric wall heaters that are 4000 watts each. I removed the heaters and now will only need to power a few two-prong outlets and six lighting fixtures. The electric company advised me to simply run a new line from a breaker in the main house's panel out to the a-frame. There are four romex wires in the a-frame that need to be tied into the feeder line. Question is, can I do this without installing a new panel in the a-frame (i.e., simply wire-nut the a-frame lines onto the feeder)? Thanks for any advice.

 

Code only allows a single circuit to a detached building without a subpanel. It sounds like your needs are modest, and thus you could probably get away with a single circuit. Most inspectors will allow this single circuit to be a multiwire circuit. Thus if you run 12/3 UF-B cable out there, you can get up to 4.8KW of power. This would seem to be plenty for what you want. Even if your inspector won't allow the multiwire circuit, you can still get 2.4KW of power out there with a single 20-amp circuit. This would also probably be sufficient.

How many square feet is this building? And are you convinced that you will need neither electric heat nor air conditioning?

 

Thanks for the response, John. The building is approx. 300 square feet. I'm going to run 12/3 UF out of a 20 amp breaker to the building, but the four wires I need to connect to are 12/2. What does this mean as far as grounding goes? Would a subpanel be required?

 

First, decide whether you need 4.8KW or whether 2.4KW will do. If you decide on the 2.4KW, then just run 12/2 UF buried 12" deep and protected by a GFCI before leaving the house.

You don't need the 12/3 unless you decide that you need 4.8KW. First check with your inspector to make sure he will allow the multiwire circuit. Then get a wiring book that explains multiwire circuits and how they work. If you decide to go this way, let us know and we can help you understand how it works.

 

If the old panel is still present in the building, why not just tie into that?

 

2.4KW will be plenty. I already have 100 ft. of 12/3 and would like to use it if possible. Can I? And if so, what should I do with the ground wire in the main panel and out in the a-frame?

btw, joed, the existing panel is an old fuse job that looked to be on its last leg.

 

and use it for a junction box. Or remove the old panel and install a junction box. This would give you the capability of using a multi-wire circuit.

Oops!! Just thought of something. You'll need a disconnecting means (switch) in the cottage.

 

sherpa, you have 12/3 NM or 12/3 UF? You can use the latter, but not the former.

How far apart are the buildings?

 

I've got 12/3 UF. The buildings are about 65 feet apart but the trench requires that I use approx. 95 feet of wire.

 

Put a 20-amp single-pole breaker in your main house panel. Connect the black of your 12/3 to the breaker screw. Connect the white where the other white wires are connected and the bare where the other bare wires are connected. Cap off the red wire -- reserved for future use.

Run the 12/3 to a new single-gang outlet box in the house. Put a GFCI receptacle in that box. Connect black and white to the line side of the GFCI. Run 12/3 out the wall of the house through 3/4" PVC conduit and down into a 12" deep trench. Connect this 12/3 to the load side of the GFCI. Connect the two red wires only to each other, and the two bare wires to each other and pigtailed to the receptacle.

Lay the cable on the bottom of the 12" trench out to your building. Come up out of the trench and into the building in more conduit.

Run the 12/3 into the old panel (strip out the guts), or a new junction box in that same location. Connect all the white wires to the 12/3 white, all the black wires to the 12/3 black, and all the grounding wires to the 12/3 bare. Cap off the red wire.

In the future (or now), if you need more power, you will use the red wire. This would require you to swap out the 20-amp single-pole breaker with a 20-amp double-pole GFCI breaker (somewhat expensive and a bit harder to find). You would also remove that GFCI receptacle, and just splice the wires through. Then in the outbuilding, you could connect half of the black wires to the red wire instead of the black wire.

 

I was wrong about my wire. What I have is actually 10/2 cable. I assume your plan still applies, just without the red wire. Two things before I do this, though: can I just put a GFCI breaker in the main panel and run the feeder out of that? Also, there are no ground wires in the outbuilding -- the cables are simply black and white but no bare. What do I do with the bare wire from the feeder? Sorry for the confusion and I really appreciate your attention.

 

You can use the GFCI breaker instead of the GFCI receptacle. It'll do the same job for more money.

If you don't have any ground wires to connect to, simply connect your ground wire from the 10/2 to the box (assuming it is metal). But also consider replacing the wiring inside the building with modern wire if reasonably feasible.

It is still UF, right?

 

Yes, it's still UF.

I'll definitely look into rewiring the building before I do any of this. Thanks for you patience and help. Nick.