A light fixture is two wires and a ground. Look at the box before you look at the fixture.
You’re replacing a ceiling light or a wall sconce. Before you buy, understand what you’re working with.
Types of existing fixtures you might be removing: - Flush mount — sits tight to the ceiling. - Semi-flush — short stem between ceiling and fixture. - Chain-hung / pendant — cord or chain from ceiling. - Recessed can — in the ceiling (different guide). - Wall sconce — mounted to a wall box.
Types of existing boxes (this matters): - Pancake box (shallow, 1/2” deep). Limited wire room. OK for most fixtures. - Standard octagon/round box (2” deep). Most installations. - Fan-rated box (heavy-duty, supports 35+ lbs). Required for ceiling fans, allowed for fixtures.
If your new fixture weighs under 10 lbs and mounts flush, any existing box is probably fine. Heavy chandelier (>25 lbs) or fan needs a fan-rated box.
Same as the outlet book: 1. Kill breaker. 2. Test with non-contact voltage tester. 3. Remove fixture cautiously and test exposed wires. 4. Never touch copper until test confirms 0V.