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In my spare bedroom, there are four electrical outlets. If I use a vacuum cleaner in one of those outlets, the breaker trips. However, if I use any of the other outlets, it works fine. Is the outlet itself bad, or is there some other kind of wiring problem? This breaker only powers the four outlets, a ceiling fan and light. I had the light (7W LED) on, and everything else off or unplugged. All outlets show 120V Hot-Neutral, and 0 V Neutral-Ground. The breaker is a 15A Combination Type AFCI Type BRAF.

  • Does an other load show this behaviour when plugged into the outlets? – DJohnM Apr 18 '15 at 19:09
  • Oddly, I was able to easily repeat the problem earlier today, but now it is not tripping under the same, or slightly higher, load that tripped it this morning. Intermittent problems are always harder to troubleshoot. – Paul Apr 18 '15 at 19:34
  • Have you checked to make sure the wires are solidly connected to the receptacle? A loose connection could be aggravated by temperature and/or current variations, which could explain the intermittent nature of the fault. – Tester101 Apr 22 '15 at 11:54
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On the contrary, that outlet is probably the one that has the most direct connection to the breaker. The additional wire between that outlet and the others is what reduces the current that the vacuum cleaner draws just enough to keep the breaker from tripping.

  • WHAT!? You're saying that the vacuum draws less current, if it's farther away from the circuit breaker? – Tester101 Apr 18 '15 at 19:24
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    Yes. The resistance and inductance of the extra wire reduces the voltage that the vacuum cleaner sees ever so slightly. Since it is essentially a resistive load, this means that the current is reduced slightly, too. A vacuum cleaner usually has a series-wound "universal" motor, which draws a huge surge of current on start-up, and this is when this effect is most significant. – Dave Tweed Apr 18 '15 at 19:26
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    If is a little farther away from the the breaker, we are only talking about miliohms more resistance or miliamps less current. That seems a little far fetched. Besides, if a standard Bissel vacuum cleaner can trip a 15A breaker, either the vacuum has some serious internal problems, or the something else is pulling a lot of current that I don't know about. If the vacuum has the problem, it should trip other breakers in the house, and it does not. Nothing else in the room is on, so if something is putting an extra load on the circuit, it would be some kind of phantom load I need to find. – Paul Apr 18 '15 at 19:53
  • I can't help you with those other issues. Your question was about why the outlets behave differently. – Dave Tweed Apr 18 '15 at 19:55
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    I think distance may be on to something. It allows the EMF induced ground or arc fault to dissipate before reaching the beaker. If that isn't it, I'd be pulling the outlets and looking at the pigtails (or just not plug electric motors into AFCI'ed outlets). – Mazura Apr 18 '15 at 22:29

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