SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/eng-gfci-line-contact

Which shock can a GFCI NOT protect you from?

Touching two hot wires (line to line), because no current leaks to ground.

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  1. Touching a hot wire while standing on wet ground
  2. A drill with a damaged cord leaking to ground
  3. Holding two hot wires at once ✔

Why: If you complete the circuit between two hot wires, the current going out still equals the current coming back. The GFCI sees no imbalance, so it does not trip.

Huh, didn't know that: That is why electricians still shut off the breaker and test before touching wiring, even on GFCI circuits.

The dad joke
The GFCI only watches for missing current. Hand it a balanced problem and it shrugs.
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References

Answer: Holding two hot wires at once. If you complete the circuit between two hot wires, the current going out still equals the current coming back. The GFCI sees no imbalance, so it does not trip.

  1. OSHA Construction eTool, Ground-Fault Circuit Interrupters www.osha.gov/etools/construction/electrical-incidents/ground-fault-circuit-interrupters
    The GFCI will not protect you from line contact hazards
    Checked 2026-10-10.

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