On 2009-08-14, ben wrote:

I have some lights in a rough space that are plug-in lights. To
power them, last year I wired up a duplex receptacle high up by the
ceiling. Power to that outlet is controlled by a single pole switch
at regular height. Here's my question: is it ok to replace that
switch with a dimmer? Nothing else would ever be plugged into the
outlet. You can't even reach it without an 8' ladder.

It is not actually NEC compliant. From the 2008 NEC, 404.14(E) states:

Dimmer Switches. 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.

So it would be better to hardwire the lights. Or there are a couple
receptacle solutions that comply with 404.14(E). You can get a
plug-in dimmer than goes between the lights and the receptacle and
uses a wireless control.

Or I believe somebody makes a special plug and receptacle that you can
use, which is marketed only for dimming receptacles for lamps. Then
you replace the receptacle and change the plug end on your lights.

Cheers, Wayne