Step 1: Cut Power
Go to your fuse box and turn off the power to your bathroom. Confirm that the power has been shut off by using a circuit test kit and/or flipping the switch to the light. Whether installing shower lights or bathroom mirror lights, safety is essential.
Step 2: Remove the Old Fixture
If the existing light has a glass cover, remove it. Unscrew and remove any light bulbs as well. Bathroom lighting fixtures are attached to the wall with decorative nuts/bolts which should be easy to spot. Have a helper hold the fixture while you unscrew the nuts. The lighting fixture should slide right out of the bracket. If there is resistance, slide a razor blade under the edges of the light to separate it from the paint. Once removed, the wires must be disconnected. The electrical wires are easily disconnected by unscrewing the plastic wire nuts and twisting the wires apart. You may now set the old fixture out of the way.
Step 3: Prepping for the New Fixture
Take a close look at the ends of the wires in the wall. If they are frayed, clip the ends off and strip 1/2 inch of insulation off the wire to reveal fresh wiring. If a junction box is not already in place, one must be installed. A junction box is a steel box which is recessed into the wall, preventing fire from spreading in the event of a short. Look for the push-in boxes with drywall hardware, as these are the easiest to install. Place the junction box over the existing wiring hole and sketch its profile using a pencil. Use a jigsaw to cut out the hole for the box. Grip the wires and pull them into the box before pushing it into the hole and securing it with the included drywall clamps.
Finally, a bathroom light mounting bracket must be connected to the junction box. The bracket will most likely be included with the fixture.
Step 4: Mount the Bathroom Light
Using the wire nuts, connect the fixture and wall wires together. Twist like-colored wires together before applying the nuts. Place the fixture over the mounting bracket and screw it into place with the decorative hardware.
Screw in the light bulbs, attach any glass covers and turn the power on at the fuse box. Flip the switch and enjoy your new bathroom lighting fixture.