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John Grabowski John Grabowski is offline
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Default Strange behavior of dimmer switch


"David Nebenzahl" wrote in message
s.com...
Just installed a replacement dimmer switch that exhibits the same
strange behavior as the previous one.

It's on a circuit that's wired correctly. I have a dedicated outlet
running a string of low-voltage halogen lights through a transformer.
When I installed the first dimmer, it worked fine. When I checked it
with my handy-dandy circuit checker (you know, the type with the 3
leds), it indicated the circuit was OK with the power applied. BUT: when
the dimmer was switched off, the tester indicated a fault ("open
neutral", it said).

So I replaced the dimmer temporarily with a single-pole switch; circuit
acted normally with power on and off.

Then I replaced the dimmer (it's a Lutron "decora"-style with the big
rocker switch on front and a little slider doohickey). Guess what? Same
deal; tester says "OK" when on but "open neutral" when off.

What gives? All I can think is that the dimmer is drawing just enough
current when in the "off" position to spook the tester. (Yeah, I know
those types of testers aren't 100% conclusive, but shoot, it's better
than sticking your fingers on the damn wires.) Why this would be the
case, I have no idea.

Although, I just realized: the dimmer packaging says "locator light" on
it; is there a dim light on this that is drawing this current? (I'm not
at my client's site right now.)

D "puzzled" N


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Forget about your tester. What is the problem with the lights? Are they
flickering? Is the transformer making noise? For a transformer load it is
usually a good idea to use a dimmer rated for a magnetic load unless the
transformer is electronic in which case use a dimmer rated for an electronic
load. A locator switch has a small pilot light that is on when the switch is
off so that you can locate the switch in the dark.