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 circuit is bypassed or the switch has failed. Common causes include a miswired line/load in the box, a failed or welded switch, a backstabbed wire making constant contact, or another control in a 3‑way/4‑way setup leaving the light energized. Smart switches or add‑on remotes can also fail closed. Berkeys troubleshoots these issues across Dallas–Fort Worth, including Plano and Bedford.

Quick checks:

• Try the other 3‑way switch location.
• Turn off the breaker before inspecting.

<br/> Updated: 2025-11-06 00:00:00 <br/>

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