How do I safely extend electrical wiring without replacing it entirely?

Question

I'm in the process of replacing a light fixture with a ceiling fan. I replaced the old mount with a pan ceiling support box. The wiring is old (1920s) and inside armored cable coming through the stud. I brought the cable into the box using a duplex clamp and am left with wiring that is too short.

What is the best and safest way to extend this wiring without having to go into the attic replace it completely? I assume I will need to purchase new wire, splice and attach with a wire nut. But which wiring do I buy? And does it matter which wire nut I use?

Answer 1

You are sunk

Wire that short can't be spliced or extended. The wire must be able to come out beyond the surface of the box at least 3".

You will need to reroute these cables to a different junction box somewhere the wiring is able reach with the needed spare length inside the box. From there, you can run a /2 w/ground cable to this location, e.g. NM or MC.

The junction box where this happens must have its cover remain accessible without needing tools to disassemble any part of the building. The attic is fine.

Answer 2

I'd use a push-in splice like this one. It should attach to your existing wires and let you attach another piece to bring up up to a better length.

As for size, you can't go wrong with 12 gauge. It will work with 20 amp and smaller.

Answer 3

I'd suggest buying a small junction box and installing it so the incoming cable has enough length, splice on new wire, then run the new wire the rest if the way to the current box.