Running electricity to fireplace.
If I need a connector in the back of the J-box that makes the hole I need about 1 1/4".
After some more thought, especially since I don't need to protect the cable as it goes through the brick, I'm going to just run bx through the hole and forget about the j-box on the brick. That will speed installation from an hour or two to about 5 minutes.
It's a gas fireplace and the electronics and fan are on the bottom with a plug to power it up coming out through the side. It shouldn't get that hot or it would self destruct.
I tear things down and build them up.