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

Most often, the switch’s internal contacts fail closed, so the light stays on. Other causes: miswired line/load, tied‑hot switched leg, failed smart/dimmer, or a three‑way with the other switch on. Loose back‑stabbed connections or neutrals can also bypass the switch. If you smell burning, turn off the breaker. We diagnose with specialized tools and up-front pricing.

• Try the other three-way switch, if present.
• See if the light turns off at the breaker.

Updated: 2025-11-05

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