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Dimmer switch problem

Hello Group,

Here's my situation: I have a five-light fixture on a dimmer switch. It's a single pole, no three-way. All was fine for years and then no light. I replaced the dimmer switch with an identical new one. The light didn't turn on. I disconnected the fixture and used a voltmeter to measure the output on the wire where I disconnected the fixture. In what is presumably the 'on' position on the dimmer, the volts vary from 120.5 down to 2.9, as is expected. However, in the 'off' position, there is still power getting through, from about 74V down to 18V when I turn the knob. I figured I had purchased a bad dimmer so I got another one. Exact same problem. Could it be another bad dimmer or can a faulty line / circuit cause a problem like this? Everything else on this circuit seems to be fine (outlets and a couple other lights). This is all happening in my bathroom and I really need to see in there.

Thanks for any help you can give.

Pamela

Reply to
pmarieo
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Or could a bad lighting fixture cause a problem in the switch?

Thanks again,

Pamela

Reply to
pmarieo

Update:

I installed yet another dimmer switch, a different type. Same thing happens, but after a closer look at the readings on the voltmeter, I found that when the dimmer is on, it varies from 2V to 120V, as expected, but when the switch is turned off, the meter fluctuates between 14V and about 74V. The voltage goes up and down, up and down, never stopping.

What's going on here?

Thanks again,

Pamela

Reply to
pmarieo

What happens if you connect the two wire together that went to the dimmer switch? My guess is the fixture will not come on. In that event you have a splice somewhere in the circuit that went bad.

Reply to
Rich.

The voltage with the dimmer off is expected behavior. When measuring a circuit that has no load on it with a sensitive meter, it will pick up voltage induced in the wire from other sources, but there is effectively no current available, so into any load there will be nothing.

Dimmer switches don't actually vary the voltage, they use phase angle control. Plenty of descriptions of that out there, but in a nutshell it varies at which point in the AC waveform the triac (switching device) completes the circuit, which determines the RMS power to the load.

If the light will not turn on, you have an open connection somewhere. Bypass the dimmer entirely, just wire nut the two wires that go to it together, and connect the light fixture. You will then have to determine where the break is. Take care as an open neutral will result in live wires even though the light will not be on. If in doubt, have an electrician or at least a decent handyman look at it, it goes without saying this can be dangerous and if you do it wrong, it can be a fire hazard too.

Reply to
James Sweet

Ignore these voltage readings, it's a red herring.

Yes, the fixture could be bad. These have a junction box in the middle where the wires from all the sockets join together. This is where I'd look first, the space is cramped and there's a lot of wires in there. Sometimes the connections come apart there.

Reply to
James Sweet

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