I'm installing an exterior junction box where I'm removing an old light fixture. I have a gasket to seal the cover to the box. But how do I seal the hole where the wire goes into the box?
I decided to fill the hole with something called "duct seal" from my hardware store. It's like plumber's putty. I stuffed it in the hole and molded it around the wire. It seems to seal the hole up pretty well and is supposed to be weather-proof.
In retrospect, I probably should have bought a junction box that has a hole in the back and put it directly over where the wire comes out of the wall. I noticed that some have caps that can seal unneeded holes but not the model I bought.