I'm replacing track lighting with slim recessed led lights. Metal electric box has black wire, white and there is a twisted copper wire that is not secured to anything. Pretty sure thatis my ground but where should it be attached?
The bare twisted wires in the metal box are your ground wires , with metal boxes they should be connected to the box and if your new lights have a green ground or bare copper connect that to the bare wires in the box also. The black is the hot and white neutral with only 3 in there and wired to code.