We are putting in a new mirror and light fixture. Unfortunately the electrical box is not centred with the vanity. I am going to drill a hole in the metal backing for the light fixture (see pictures) to put the wires through, but i'm not sure about what is a safe way to ground it. The guy installing the mirror will then fix the fixture's backing onto the the mirror.

  • can I make a new hole for the green ground screw closer to where im cutting the larger hole for the wires to go through?

  • alternatively can I use a twist wire cap to connect both grounds together, then loop a section of the newly connected one to the ground? (the ground coming out of the wall isn't long enough to reach the current ground screw once repositioned)

Sorry if it's obvious, just want to make sure I do it safely thanks for the help!

Update: Thanks everyone for the replies, they were all helpful and appreciated. I installed it yesterday and it worked out great, thanks! I've added a picture with the final product.

electrical box

light fixture back

light fixture

Final light

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3 Answers 3


Yes you can cut the hole but you need some protection for the wire coming through the hole I would find a large snap in gromet drill a hole to fit the gromet I would move that 10-32 green screw to the point the wire comes through and tie your ground there but you can make a jumper in this case with a wire nut. You need to protect the wires from getting cut if you can’t easily find a large enough firewall gromet , snap in gromet , snap in bushing you need some type of protection I like 3/4 snap in bushings the big box orange store has a bag of 3/4 acc snap ins for 2.23 a bag of 10.


The incoming cable’s ground wire goes to the junction box.

It does not go to the lamp.

If you want to bring a ground wire through that hole you are drilling, it either needs to pigtail off the above grounds, or go to a second ground screw hole you add to the box.

You can add a ground screw to a junction box by drilling a hole correct for a #10-32 tap, then tap the hole or use a self tapping screw. The -32 or finer thread pitch is essential, do not use a sheet metal screw.

Since you are now running an additional ground wire, length to reach the OEM ground screw won’t be a problem.

Or, drill a couple extra holes to tie to the junction box with the normal screws

If you know how the light will be positioned, then drill holes that line up with the mounting screw holes on the junction box. One screw will ground you.

  • I would recommend a Garvin GSST, just to save them the pain of tapping and drilling Commented Jul 3, 2020 at 20:13

Sometimes it's just easier to move the box. You'll have to drill a hole large enough for a nonmetallic bushing or a romex connector. Get a 2' piece of romex 14/2 with ground and splice it in the junction box. Pull the romex into the fixture bracket and hook the romex to the fixture wires.

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