I have a 3/4" thick man made quartz backsplash in the kitchen. The electrical box cut outs are not quite big enough for the box extender. The electrician says I need the box extender and that the backsplash guys often have to trim their installs for them to fit. The backsplash guy says he has done 100s of houses and never had to trim a cut out for an electrician.
Is this a code requirement if so what is the idea behind the code? Is it a fire concern since the box could have an air gap between the backsplash and the drywall. Could I fill that with a fiber reinforced drywall setting compound?
There are two 3 gang cut outs in this installation. I tried a silicon carbide grinding stone in a 1/4" 20k rpm air grinder which did very little material removal. I also tried a rotozip XB-FTC1 which also did very little.
The box behind the quartz backsplash is a grey electrical box. The electrican has tried to use the Arlington BE-3 which when forced into the hole is distorted in the horizontal direction as the cut out is not wide enough to accomodate the box extender.
I did have the backsplash guy come out and I had an angle grinder with a 3 3/8" blade. He couldn't think of what tools he could use to do it so he gave my tool a try. The blade did a good job cutting into the sides but then the backsplash guy wasn't sure how to safely cleanup the corners so he said he'd think about what tools he could use. He also marked up the backsplash a bit with the grinder blade protector and gashed the quartz a bit outside of his cut which is hopefully still going to be hidden by the cover plate.
Given the electrical code issue pointed out below by NoSparksPlease what should I do? I could try the XB-FTC1 in my 30k dewalt cut out tool but given the very small amount of material that was coming off via the die grinder I think it would take hours. Any tool recommendations to cleanup the corners where the angle grinder couldn't get without over cutting the hole?
I'll re-post the hole cleanup / recommendation question separately as I've received the code question answer.