Replacing Fixtures and Adding New Light
Most indoor lighting projects fall into two groups. The first is replacing an existing fixture, such as trading an old flush mount for a new ceiling light or chandelier, or updating bathroom vanity lighting. The second is adding light where there was none: recessed lighting in a living room, pendants over a kitchen island, wall sconces in a hallway, or a ceiling light in a bedroom that only had a switched outlet.
Replacing a fixture often uses the existing box and wiring, but not always. The box has to be suitable and secure for the new fixture, and the wiring has to be in good condition. Adding a fixture where none exists usually means running new wiring from a power source and often adding a switch.
A new fixture does not fix problems elsewhere on the circuit. If lights flicker, dim or go out across a room, the cause should be found before new fixtures go up.