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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.

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  • Does an other load show this behaviour when plugged into the outlets?
    – DJohnM
    Apr 18, 2015 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, 2015 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, 2015 at 11:54

2 Answers 2

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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.

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  • WHAT!? You're saying that the vacuum draws less current, if it's farther away from the circuit breaker?
    – Tester101
    Apr 18, 2015 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, 2015 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, 2015 at 19:53
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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, 2015 at 22:29
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    @Tester101: No, that's incorrect. If there's more resistance in the circuit (for whatever reason), the current will be less.
    – Dave Tweed
    Apr 22, 2015 at 17:46
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You sound you live in a house with an illegal safety code. One sure way to find out if the house wiring is breaking the safety electrical code, test every AC receptacles with a $1 AC pen tester. if both a Neutral (White) or the Live (Black) wires lights the pen, then you need to call a "certified electrician" to pinpoint which non polarize receptacle is causing the problem which won't take 30 minutes to find and fix.

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