Double voltage at a standard receptacle is a serious miswire — shut the circuit off and have it corrected before use.
Stop and call a licensed electrician or emergency services now if there's smoke, sparks, a burning smell, heat, shock, or water near the problem. Otherwise it's safe to answer the questions below.
The likely readout
Most likely cause
About 240 V at a 120 V outlet — a serious miswire; shut the circuit off
Ranked by fit to your answers
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About 240 V at a 120 V outlet — a serious miswire; shut the circuit off
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SAFE NEXT CHECKStop and shut the circuit off at the panel. ~240 V on a 120 V receptacle is a wiring fault that can destroy plugged-in equipment and is a shock hazard; have it corrected before use.
Where to stop. Measuring at an accessible outlet or on a disconnected wire/fuse is homeowner-safe with a properly rated meter. Anything that requires probing energized wiring inside boxes or the panel is a licensed electrician's job. Note that digital meters can read phantom (ghost) voltage on a dead conductor — confirm a live/dead decision with a low-impedance meter or a solenoid tester, never a single high-impedance reading. This is general information, not a quote and not a substitute for a licensed electrician.
Try the safe next check above. If it doesn't resolve it, or would mean working on wiring or a panel, stop and call a licensed electrician — don't replace parts on a guess. Open the full tool to change any answer for your exact situation, or try a related check below.
source-governed · verified 2026-06-20
Sources
standard ANSI C84.1 — nominal voltage ranges (120 V service) · verified 2026-06-20
Electrical Fault Check provides general diagnostic information only. It is not professional advice, not a quote, and not a substitute for a licensed electrician. Do not work on live wiring. If you see smoke, sparks, burning smell, heat, shock, water exposure, or repeated tripping, stop using the circuit and contact a licensed electrician or emergency services as appropriate.