Dimmer switch questions

Feb 17, 2011 20 Replies

I am trying to figure out a dimmer switch at my mother's house.



I can't find any voltage at the light fixture, which is strange because it used to work. The fixture is gone, just wires for now.



The house is 56 years old.



There aren't any tripped breakers and other outlets in the room have current.



Any ideas of what to check next?



Andy


Maybe the dimmer feeding the light is bad. Remove the dimmer and connect the wires together, then see if you have power at the light

re: "Remove the dimmer and connect the wires together"

Oh boy...why do I picture this going very badly?

The first question is how many wires are in the light box? Was the dimmer used for the missing light? Did you try to test power with the dimmer on?

Some dimmers don't work without a load.

Yes, that's what I was thinking too. It may need a minimum load to turn on and if he's using a high impedance VOM, might not turn on at all.'

This is pretty basic:

1 - Is 120V present on the input lead of the dimmer?

2 - IF yes, then connect up a load like a small lamp or drop light as the dimmer load and see what happens.

If you don't understand how to do 1 and 2 safely, call an electrician

I will have to go check, I know there at least 4 wires.

I already tried testing it with a light socket and bulb.

Next step is going up into the attic.

There is blown in insulation, so it will be fun trying to find the wires. :-)

Andy

I will have to go check, I know there at least 4 wires.

I already tried testing it with a light socket and bulb.

Next step is going up into the attic.

There is blown in insulation, so it will be fun trying to find the wires. :-)

Andy

Where the fixture was, there were only two wires attached to it coming out of the ceiling box, not including any ground conductors. With the dimmer removed and the and the wires that were attached to it shunted together, not including any possible ground wires, you should have 120 volts at the two wires in the ceiling that were formerly connected to the fixture

I don't know - if it is not a 3 way dimmer it only has 2 wires - pretty hard for even a NOOB to screw that up???

Hardly a "noob", I have got it repaired.

Can I do some work for you? My rates are fairly reasonable.

Andy

It turns out that the dimmer was bad.

I replaced it with a simple switch.

Andy

Dimmer circuits can be a PITA especially for the DIYer. Some of them dont come on unless there is a load in place so if the bulb is blown or missing they dont appear to work. They can be bad and its not easy to do a contiuity check. Bulbs and switches are cheap.

Jimmie

You're right.

As far as their use for lights, I would say their days are numbered.

With CFLs and all.

Andy

re: "Remove the dimmer and connect the wires together"

Oh boy...why do I picture this going very badly?

--------------------------------------------------------

Nah, it's the right thing to do. A dimmer is really only a switch, albeit a special kind of one. Shunting the circuit around it would be the same as wiring in a standard toggle switch in the ON position. That's probably a better way to test the circuit although a circuit tester or meter would tell you which of the two wires was hot and which went on to the bulb.

- Bobby G.

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I know all about switches, I just get a little nervous when I see a question worded the way it was and then the suggestion to just short the switch out.

Hmmm, You know all about switches? That makes me nervos!

.

...

On the use group you never know the experience level of the one you are advising. Saying something like that can be dangerous. I can imagine that there are those that may takse "shorting a switch" as conneting the hot wire on the switch to the neutral. OUCH!!!.

Jimmie

...

What's it feel like to be "nervos"?

I know all about switches, I just get a little nervous when I see a question worded the way it was and then the suggestion to just short the switch out.

Just to clarify, I never suggested "shorting" the switch. I said remove the switch, then connect the wires together. There will either be two or three wires that were connected to the dimmer, depending upon it being a single pole or 3 way. Just connect them all together and you've effectively bypassed the switch, at which point, barring other wiring problems, there will be 120 volts at the light. In a subsequent reply, I used the term "shunt" which essentially means the same thing

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