Dimmer Question

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sparky_magoo

sparky_magoo

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Reno
I went on a service call today. The HO just moved in. He didn't know how the lighting switches might have worked. I found five bad dimmers. The HO went to "Big Orange" and came back with five Leviton dimmers for me. I installed all five.

Two dimmers didn't work. I discovered they were on the same lighting ckt. In other words, two dimmers on one three way ckt.

The problem was this, the lights would flash on and off, at about once a second. I replaced one dimmer with a three way switch. The ckt. works fine.

Before replacing one dimmer, I by-passed each of the dimmers, one at a time. The ckt. would work with either of the dimmers by-passed. I know both dimmers are OK.

I understand two dimmers on one three way ckt. is retarded, but why did the two dimmers cause the lights to flash on and off? I don't get it.

Any enlightenment would be greatly appreciated.
 
sparky_magoo said:
Two dimmers didn't work. I discovered they were on the same lighting ckt. In other words, two dimmers on one three way ckt.
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The dimmers and the switches have to match: two wires or three. This should have been impossible to miss upon installation.

I understand two dimmers on one three way ckt. is retarded, but why did the two dimmers cause the lights to flash on and off? I don't get it.
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Not sure, but one guess is that the dimmers were alternating which one was conducting fully and which was doing the dimming.

Dimmers dim the bulb by delaying the turn-on point on each half of the sine wave, but they expect to be supplied from an intact power source.

Dimmers get their power through the load, but two dimmers in series do weird things. Try plugging a dimming lamp into a dimmer-controlled receptacle.
 
The new dimmers did match. But, I don't think they were desighned to work together. I corrected the problem by replacing one dimmer with an ordinary three way switch.

Again, my question is this, Why were the lights blinking on and off?
 
sparky_magoo said:
The new dimmers did match. But, I don't think they were desighned to work together. I corrected the problem by replacing one dimmer with an ordinary three way switch.

Again, my question is this, Why were the lights blinking on and off?
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because they weren't blinking Off then On.
 
I believe acrwc10's comment was one of sarcasm or trying to be funny.

I am not sure why they were blinking but if one dimmer is dimmed then the other 3 way dimmer must get confused by the situation. It may need more power to function properly.

Lutron makes a dimmer called the Maestro that will work from up to 10 locations. You buy one master dimmer and the others must be slave units. Home depot sells them. They are the decora style dimmer.
 
i always thought in a 3-way lighting system, u have to have 1 3-way dimmer in one box and a 3-way switch in the other box to have it work correctly. just wondering if that is correct?
 
dimmer question

dimmer question

The dimmer switches are fighting for control of the lamp, and effectively cancelling each other out. There is no communication between the two so they are both the "Master" dimmer. You can use the Lutron Maestro dimmers, or lightolier also makes several multilocation 3 ways. IN each, you have a "control" wire that goes between the two dimmers, basically communicating from one to the other"I have controll now, I am dimming 75%." If you were to go to the other dimmer and operate it, it would send a signal back "Now I have control, go back to 100%" and the two would work in unison, because the control wire is going to operate the other dimmer at the same rate and time as the one you're physically standing at and operating.

Hope that helps.
 
cloudymacleod said:
i always thought in a 3-way lighting system, u have to have 1 3-way dimmer in one box and a 3-way switch in the other box to have it work correctly. just wondering if that is correct?
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That is sometimes correct. Most dimmers you must use a 3way dimmer along with a 3 way switch but they make some that can operate from 10 locations. Read my post that is above yours.
 
I ran into the same issue in a house that wanted to control two locations with each location having a 3-way Dimmer....BUT the same thing happened and when one was replaced with a standard 3 way it worked fine.

I believe it is in the dimmer feature....very hard to dim at one location and then increase the light again at another....so I would agree it was probably a standard 3-way dimmer for one location setup........and as Dennis stated that do make multiple location dimmers.......

Now I am only shooting in the dark on that because I also has the 3-way dimmers and it stated right on the box used with another 3-way dimmer to create (2) 3-way dimmer setup.....but alas as you stated it did the same thing and did not work......

In the end...I said....Dim the puppy from one location and be happy....:)
 
radiopet said:
Now I am only shooting in the dark on that because I also has the 3-way dimmers and it stated right on the box used with another 3-way dimmer to create (2) 3-way dimmer setup.....but alas as you stated it did the same thing and did not work......

:)
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I have never seen a 3 way dimmer that can dim from two locations unless one of the units is a master and the other a slave. Are you sure you didn't need a slave for the other? What brand was it?
 
Thats what I thought as well Dennis.....lets me see if I can find the models again....in the end I just did not use but one of them and they were happy enough but it was strange to see a post almost similar to the thing I ran into.

I have done plenty of X-10 and so on setups with slaves and masters and so on but this was listed as able to used at both ends of a 3 way setup...and still work...sad to say I BEF to differ with them as it did not...lol

I will see if I can find it.....

Ok....here is the image of it.......
 
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skylark.jpg

That looks like a lutron Skylark dimmer that is not capable of 3 way dimming from both locations. They do not make a slave unit for that. If it was labeled as capable for that function then I bet it was labeled wrong.
 
to dim from more than one location, you need what's called a digital "smart dimmer". almost everyone is making some version of it now. usually if you buy them from a retail outlet, they will come in pairs. works on standard three-way wiring. one of the travelers becomes a control wire. the lutron maestro is a very popular smart dimmer. and i think leviton makes a toggle touch smart dimmer. they do work.
 
they do make dimmers that dim from each end but the last time i checked
they were like 80 bucks a pair.. regular 15 doller dimmers wont work
you have to have a regular 3 way in the circuit....
 
I think we're slightly off topic from my original question. The intent was not to dim from two locations. The two three way dimmers were installed to replace existing burnt out dimmers. The HO just moved in. He never knew how the lights might have once worked.

When I inadvertantly installed two three way dimmers on the same ckt., why didn't they work? With both dimmers on max. brightness, why did the lamps rapidly blink on and off?
 
Sparky -

I don't think anybody is going to know. You're asking why a piece of equipment operated in a undefined manner after it was connected and operated in a fashion not known to the mfg or us.

carl
 
It is an interesting thought - what was the flicker like?

The way you described it in the original post, it sounded as though it looked like a car's turn signal. That would be weird. I'd expect it to be extremely jittery, or to dim unevenly (but dim without noticing the light going out at any given moment).

As was explained before, a single dimmer working properly shuts the light off for a moment each cycle. I would expect two of them in series (improperly installed) to be doing the same thing at different times in the wave.

It must be that the triac in the second dimmer had a hard time getting a rhythm with the power getting shut off for a moment 60 times per second, so in the confusion it shut off for more than a few cycles. Maybe?

Got an oscilloscope and a couple dimmers to burn? :D
 
georgestolz said:
It is an interesting thought - what was the flicker like?

The way you described it in the original post, it sounded as though it looked like a car's turn signal. That would be weird. I'd expect it to be extremely jittery, or to dim unevenly (but dim without noticing the light going out at any given moment).

As was explained before, a single dimmer working properly shuts the light off for a moment each cycle. I would expect two of them in series (improperly installed) to be doing the same thing at different times in the wave.

It must be that the triac in the second dimmer had a hard time getting a rhythm with the power getting shut off for a moment 60 times per second, so in the confusion it shut off for more than a few cycles. Maybe?

Got an oscilloscope and a couple dimmers to burn? :D
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george you may be close to something there. if you have the forward-phase being sliced, it may be possible that the second dimmer would locate the zero-crossing out of sync. it sounds, and probably looked, like a dimmer in slow-motion.
 
Interesting thought George. The "flicker" was very consistant. It was definitely faster than 60 hz. I would guess 120 hz. Perhaps, the dimmers were switching every half cycle.
 
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