SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/elec-open-switch-not-safe

You see an open disconnect switch. Does that prove the circuit beyond it is dead?

An open switch is not proof. Test first.

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  1. Yes, if the handle is down
  2. No, you still have to test for voltage ✔
  3. Yes, if there is a tag on it

Why: The handle position doesn't tell you what is inside, and someone else could close the switch. A mechanical failure could also leave parts live.

Huh, didn't know that: EC&M puts it this way: just turning off the power does not make a circuit safe.

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The breaker kept tripping, so I took it on holiday, now it is much more relaxed.
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References

Answer: No, you still have to test for voltage. The handle position doesn't tell you what is inside, and someone else could close the switch. A mechanical failure could also leave parts live.

  1. EC&M: 10 Questions Every Electrical Worker Should Know www.ecmweb.com/neca-show-coverage/article/55021477/10-questions-every-electrical-worker-should-know-how-to-answer
    Just turning off the power does not make a circuit or circuit part safe.
    Checked 2026-10-10.

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