The light dimmer of my chandelier broke recently so I went buy a new one (incandescent 120 V 600W). The one that broke was fairly old (sticker on the dimmer mentions 1987).
Since I'm pretty novice about electrical stuff I took a few picture before installing the new one.
As you can see it is sharing the wallbox with a light switch and there was two black wires connected in the wall. The dimmer I bought has a third green wire for grounding. What should I do with this third wire ? For now I capped it and it's working fine but I'm concerned about safety. Shouldn't this be connected somehow ? If so where ? I'm not sure that the wall box itself is grounded.
Thanks in advance for your help.