20A fuse not tripping?

balee123balee123 Solar Expert Posts: 86 ✭✭
I was measuring the current going into a 20A circuit breaker in my main panel using a clamp meter. I was seeing 25A for at least 1 minute or more. The breaker did not trip. I understand that they might not trip right away, but is this within that realm of tolerance? What is the best way to test a circuit breaker? FYI, loads into the circuit were a gas dryer (just the tumbler), washing machine (agitation cycle), and a microwave rated at 13.3A. There may have been a small wine frig going on this circuit at the time as well.


  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: 20A fuse not tripping?

    if you suspect the breaker is faulty go right ahead and replace it. it may be good and just didn't have enough on it to trip over time as you said, but that is pushing things to the limit too and worth the effort to just buy another to be sure. just my opinion.
  • BB.BB. Super Moderators, Administrators Posts: 31,765 admin
    Re: 20A fuse not tripping?

    Thermal Breakers are not that accurate... Page two of this pdf download document (random breaker) lists a typical current vs trip time profile... For a breaker running running 20% over current--You may be looking at 20 minutes to "forever" as a legal trip.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: 20A fuse not tripping?

    Just FYI, the washer and dryer ought to be on thier own dedicated breaker. Not a bad idea for the micro as well.

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