How do I fix my wiring/electrical problem that just started occurring?

March 8, 2007 3:57 PM

How do I fix my wiring/electrical problem that just started occurring?

ElectricianFilter: I have a ceiling fan and light mounted on my ceiling. One of my walls has two switches -- one is a Lutron Ariadni Fan Control and the other is Lutron Ariadni Dimmer. The second wall has a standard on/off switch that also controls the light.

Everything had been fine, until tonight. The light was off. I flipped the dimmer and nothing happened. I checked the position of the dimmer and it had no effect. I put the switch back to off (down). I then flipped the switch on the other wall from down => up and the light turned on. With the light on, I went to the first wall and flipped the switch -- nothing happened. But sliding the dimmer did alter the brightness of the light. Throughout all this, the fan control worked as expected.

How can I fix this? I want the dimmer to turn on, off, and control the brightness of the light, and the other light switch to turn the light on and off. Any help is much appreciated.

Thank you

posted by seinfeld to home & garden (10 comments total)

I should add -- once the light is on (by using the second simple switch), either switch will turn off the light. But only the second switch will turn it on.
posted by seinfeld at 4:10 PM on March 8, 2007

If all the switches worked perfectly before tonight then I would think you should replace the dimmer switch. If everything works except the dimmer switch isn't that the probable source of the problem?
posted by JayRwv at 4:11 PM on March 8, 2007

Perhaps you posted before I got my response in -- The dimmer switch, as I just typed, does turn off the light -- it simply wont turn it on.
posted by seinfeld at 4:14 PM on March 8, 2007

It seems clear that the on-off part of your dimmer switch is broken; when you say it can turn it off, my guess it is merely turning it down so far you can no longer see it.
posted by jamjam at 5:15 PM on March 8, 2007

Whenever you have a single fixture controlled by 2 different switches, both those switches need to be 3 way devices. It sounds like your dimmer is a standard 2 pole dimmer, but you could replace it with a 3 pole version, and solve the problem.
posted by paulsc at 5:39 PM on March 8, 2007

paulsc: This set up has worked for the past six weeks, since installation of the dimmer. This funny situation started acting up this afternoon, seemingly out of the blue.
posted by seinfeld at 6:37 PM on March 8, 2007

seinfeld, if you used a 2 pole dimmer, and hooked it up to the third wire, it could have "worked" for a while, as triac controls are just back to back wired SCR's (silicon controlled rectifiers). But as soon as either side of the SCR circuit lost a pull up resistor path in its bias network, you'd have the situation you describe. Use a 3 way dimmer, and you get a little extra logic that checks the position of the other switch via the 3rd wire, and prevents this from happening.
posted by paulsc at 7:03 PM on March 8, 2007

So, to be clear..

1. By whatever means, the light is on
2. You flip the toggle on the dimmer-switch, and the light goes off
3. You flip the toggle on the dimmer-switch again, but the light stays off

That doesn't make sense to me.
posted by Chuckles at 12:29 PM on March 9, 2007

You got it. Weird, eh?
posted by seinfeld at 7:00 PM on March 9, 2007

Certainly you should be using a 3-way dimmer in this application, but it will only be useful if the wiring in your walls supports it (you must have at least 3 conductors plus ground between the two switches).

Did you do the work? Can you tell us which wiring scheme was used based on paulsc's first link? How many connections (screws, or wire stubs) on the dimmer and the other switch?

If you are describing the symptoms exactly correctly, the only explanation I can think of is a fault in the dimmer, but..
posted by Chuckles at 10:31 AM on March 10, 2007