I was in my kitchen and decided to take something to the patio. I flipped the light switch, which is a dimmer. Once I did that, all the lights in the surrounding area went out. Not the entire house. We went out to the breaker box and nothing was tripped. My husband then flipped the breaker switch that is responsible for these areas and the lights came back on. To test, I duplicated the scenario and the same thing happened. Not sure what to do or what’s wrong.

  • do you have regular breakers of fancy looking one, with buttons and light
    – Traveler
    Commented Sep 16, 2022 at 1:18
  • 2
    Sounds like a nuisance AFCI or GFCI trip. LIke @Ruskes asked, does the breaker for that circuit have a "test" button on it? Commented Sep 16, 2022 at 3:23

2 Answers 2


Two key clues:

  • to the patio That means "outside". Outside often means vulnerable to weather. Has it rained recently? Even if it has not, but certainly if it has, you could have water in a light fixture or a junction box between the switch and the lights. That can cause an actual short or a ground fault.

  • nothing was tripped There are two kinds of breaker trips: overcurrent and AFCI/GFCI.

Overcurrent is what we are all used to: A 20A circuit gets 50A (or even more in a "dead short") and quickly trips. Breakers are now designed to "trip" (stop current flow) even if the breaker handle is physically held in place. As a side effect, it is possible for an overcurrent trip to happen without any visible movement in the breaker panel.

AFCI/GFCI is actually two different things, but they have a key in common: if they are protected by a breaker you do not necessarily get the usual "trip" that you get in an overcurrent situation. Current is still cut off, but through a different mechanism. GFCI is the one most people are familiar with, known by the TEST and REST buttons on receptacles in kitchens and bathrooms. But GFCI (and its cousin AFCI) can be on breakers instead of at point of use.

In all of these cases, turning the breaker "off" (though it was actually already "off") and "on" will fix the problem, at least until the next trigger event. But if it is an AFCI or GFCI trip then you may (depending on the breaker design) be able to press a RESET button on the breaker.

Outside receptacles are required to have GFCI protection. Outside lights are generally not required to have GFCI protection. But they often do have GFCI protection, either because they share a circuit with outside receptacles or just because somebody decided it made sense.

My hunch is that your trip was due to rain or condensation in an outside light fixture or junction box, either GFCI or an actual overcurrent trip.

Take a look at your breaker. If it has a RESET button on it, or any writing about AFCI or GFCI or "Testing" or an indicator light, read carefully and figure out how to:

  • Determine if a trip is AFCI, GFCI or overcurrent (it may be easy to figure out or it may not)
  • Reset it from an AFCI or GFCI trip that did not involve an overcurrent trip. An overcurrent trip always requires actual breaker movement to reset, but AFCI and GFCI often do not.

Then see if you can reproduce the problem and check the breaker to see if it either indicates an AFCI or GFCI trip or responds to a RESET button.

If this turns out to be a GFCI trip then the usual solution is to track down which location (should be something controlled by the dimmer) is causing the problem, dry it out and see if that fixes the problem. Not all GFCI trips can be solved by drying things out - sometimes there is insulation damage or component damage requiring replacing things to properly fix it.


Loss of power in a circuit can be caused by an overload that trips a breaker or a broken wire.

You seem to have the second, and the dimmer might have a loose connection.

Turn off the breaker and check all connections on that circuit, might be one at the dimmer, but might be somewhere else also.

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