What causes a light switch to stop working but light stays on?

A light that stays on when the switch “does nothing” usually means the switch or wiring is bypassed or miswired. It can also be a failed switch or a smart/dimmer issue.

Quick checks:

• Failed switch mechanism or broken toggle.
• Line and load tied together in the box (bypasses the switch).
• Miswired 3-way switch, so the circuit never opens.
• Smart switch/dimmer with a stuck relay or missing neutral.
• Fixture wired to an always-hot feed, not the switch leg. Turn off the breaker before inspecting.

<br/> Updated: 2025-11-03 00:00:00 <br/>

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