Every bathroom requires lighting, but you must choose the right kind of light fixture for each specific bathroom. Whether you are designing a new bathroom or remodelling an old one, choose a light that fits the space available and matches the colour and style of the bathroom. When installing the ceiling light, have an assistant with you to help hold the light up while you are attaching the wiring. Take your time with the project, since there is an element of danger to working with electrical wiring.
Shut off the power to the bathroom at the breaker box and remove the screws in the old light fixture's cap piece that touches the ceiling. Undo the screws that connect the light fixture's crossbar to the electrical box in the ceiling and lower the old fixture from the ceiling.
Use a noncontact voltage meter over each wire in the electrical box to ensure all electricity to the bathroom has been shut off. Twist the wire nuts counterclockwise to remove them, then remove the old fixture completely.
Turn the electricity to the bathroom back on at the breaker box and use the noncontact voltage meter to make sure there is electricity going to the coloured or hot wire in the electrical box. Touch both the hot wire and the metal box or the ground wire with the leads of a neon voltage tester. If the light on the tester illuminates, you can proceed with installing the light; otherwise, call a licensed electrician to install a ground in the box.
Turn the electricity to the bathroom off at the breaker box and attach the mounting strap to the new light's cap piece. Screw the crossbar into the holes in the electrical box, securing it to the ceiling.
Twist the neutral wires from the box and light fixture together using a wire nut, and attach the hot wires together using another wire nut. Twist the ground wire around the box's grounding screw clockwise several times.
Tuck the wires into the electrical box, then attach the light fixture's cap piece to the ceiling, using screws. Install any covers and bulbs needed in the new light fixture, then turn the electricity to the bathroom back on at the breaker box.