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Old timer at work told me to trust the circuit breaker and not the multimeter
Honestly, I was testing a bad landing light circuit last week and kept getting 12 volts at the connector. My buddy Mike, who's been doing avionics since the 80s, said 'check the breaker again even if it's not popped.' I thought he was crazy because I already pulled out my Fluke and it was fine. Turns out the breaker was weak and tripping under load at 8 amps instead of 15. Has anyone else dealt with a breaker that shows good voltage but fails under a load?
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grantschmidt20d ago
A weak breaker tripping under load like that would have fooled me too. I had a very similar thing happen with a fuel pump circuit years ago and it drove me nuts for two days. The voltage checked out fine with no load but the pump would just quit after a few minutes of running. That old timer might have saved you a lot of headache because most guys including me would have replaced the landing light assembly first. It is scary how often a breaker can look good on a meter but be completely shot inside. I started carrying a cheap load tester after that experience just for situations like this.
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black.pat20d ago
Man, that's exactly what happened to my buddy Mike with his boat's bilge pump last summer. He spent a whole weekend chasing gremlins, swapped out the pump, the float switch, even rewired a section of the harness. Turned out the old breaker would hold fine with no load but would trip after about ten minutes with the pump running. He was ready to sell the whole boat until a marina guy suggested just swapping the breaker.
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julia_miller2420d ago
Man, ain't that the truth. I have been bitten by a weak breaker like that before and it cost me a whole Saturday. Like @black.pat said, swapping the pump and wiring is the easy mistake to make, but the cheap fix is swapping the breaker first every time. Load testers are cheap insurance.
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