I replaced an old ceiling light fixture with a new one. The old fixture was on a simple on-off switch. The new fixture can work with a dimmer. I want to make that change. The wiring for this circuit is "BX" (metal encased). I was told by an electrician that that metal surround can be used to provide the ground. The dimmer has a ground wire.When I opened up the metal switch box, I noticed that there was no ground wire, and no hole in the box to add a ground screw etc. A neighbor told me that I could wrap the ground wire around one of the screws used to attach the metal part of the dimmer to the metal switch box. (Finally) my question: will that provide the ground ? As always, thanks in advance [I realize that I'd lose the ground if I pull the dimmer out-of-the-box, but then the power would be off.]

I have 3 switches that control my hallway lights depending on their position not all are working. I have 2 3-way and 1 4-way switches. I noticed in the 4-way box there is a black and a white wire with a wire nut and 2 white wires in another wire nut could the black and white wire together be my issue?