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I live in an older house and have some outlets in our kitchen that don't make sense to me. We have one outlet that is tied to a dimmer switch on the opposite side of the room. I can detect that the outlet is hot using my voltage detector (when the dimmer switch is all the way on), but it pulses. I get about 6-7 beeps, then it skips one, beeps 6-7 more times, skips, continue. My GFCI tester shows an open hot. The outlet doesn't work.

I'm not very experienced with electrical work but this sounds highly unusual to me. Where should I start with fixing the issue?

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    Get yourself a volt-ohm-ammeter. Voltage detectors are insufficient to diagnose this class of problem. Notwithstanding, as @bib posted, you never should connect an outlet to a dimmer output. – Carl Witthoft Oct 4 '16 at 15:12
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    Plug in a lamp with an incandescent bulb. Incandescent bulb is invaluable diagnostic device, as it provides not only indication but load as well. – Agent_L Oct 4 '16 at 15:52
  • Wouldn't that pulsing indicate that the dimmer is probably an SCR, which is basically turning on and off the current several times per second in order to reduce the average power delivered to the socket? At any rate, the answer below is correct: do not use any kind of dimmer on an outlet. – cjs Oct 4 '16 at 17:42
  • You don't say where you are but this seems fairly common in some European countries. I've stayed in an Italian hotel where the only socket (that wasn't an ancient one my adaptor didn't fit) was on a dimmer with the main lamp plugged in to it. I've also seen this in UK houses where it probably isn't allowed except possibly with a 2A (lighting) plug. – Chris H Oct 4 '16 at 19:36
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Outlets are not supposed to be dimmed!

While this might seem like a good idea if you wanted to plug in a table lamp that lacked its own dimmer, it creates a dangerous situation since outlets can accommodate any device with a plug, and some devices, such as many motors, react very badly to the output of a dimmer. It is forbidden under 404.14(E):

General use dimmer switches shall be used only to control permanently installed incandescent luminaires unless listed for the control of other loads and installed accordingly.

The other load dimmers are for fluorescent, LED or CLF fixtures. Dimmers are not listed for standard outlets.

The first thing I would do is replace the dimmer with a standard switch. (Done with power from the breaker turned off.) I would also check the outlet to see if it appears to be wired correctly -- black wire to brass, white wire to silver, green/bare to ground. Restore power and check the outlet again.

Supplement Also see the answer by @ThreePhaseEel that explains specialized outlets that can be dimmed, and the associated code.

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    Yeah. The dimmer seemed odd. I think the kitchen was remodeled and when they did it, they added a dimmer for a light that's on the same circuit and never removed or rewired the outlet that I'm working with now. So I should be able to just remove the old dimmer switch, wire in a new standard switch, and check the wires on the outlet and it should (hopefully) be ok? – ChickenOnAGoat Oct 4 '16 at 11:13
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    Outlets with specially-designed receptacles and matching plugs can be legally dimmed. Lutron has a set, though it's rather expensive. – isherwood Oct 4 '16 at 13:07
  • @isherwood I'd imagine that's covered under "unless listed for the control of other loads and installed accordingly", where said specially-designed receptacle counts as an "other load". – Doktor J Oct 4 '16 at 15:44
  • Could be. Just offering some clarification to the legalese. – isherwood Oct 4 '16 at 15:49
  • nota: incandescent luminaires are being phased-out in many countries: en.wikipedia.org/wiki/Phase-out_of_incandescent_light_bulbs – njzk2 Oct 4 '16 at 22:12
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This is indeed a dangerous situation, as some loads (such as motor and linear transformer loads, as well as older switching power supplies) have quite a dim view of being wired to an ordinary dimmer. In fact, the 2014 NEC added a section to address just that situation:

406.15 Dimmer-Controlled Receptacles. A receptacle supplying lighting loads shall not be connected to a dimmer unless the plug/receptacle combination is a nonstandard configuration type that is specifically listed and identified for each such unique combination.

While such plugs do exist (Lutron makes the HDTR/DDTR receptacles and the mating RP-FDU plug for this application), they are a) expensive/not widely available and b) require modifying your lamps to use the new plug. It's easier to replace the dimmer with a simple switch, as proposed.

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    +1 Added a reference to your answer in my answer. Good info. Code that I did not know about. Also thanks to @isherwood for surfacing this variant. – bib Oct 5 '16 at 15:18
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If it 'doesn't work', replacing the dimmer with a switch may not give you a working outlet, depending on what's causing it to not work.

Try cranking the dimmer to max. and plugging in a (dimmable) lamp. If the lamp works, you have a functioning circuit and you can just replace the dimmer. If the lamp doesn't work, the issue may be in the dimmer or in the wiring.

Pulses are not unusual: some dimmers work by rapidly switching the power supply on/off. The longer the pulse, the more light you get. This plays havoc with motors, fluorescents etc.

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