# Using a Motion Detector with a Dimmer?



## HandyMensch (Feb 3, 2009)

Hi,

I would like to connect a leviton motion detector light switch to a leviton dimmer switch which will control a bunch of potlights in a room in the basement.

My idea is that 120V will feed the motion detector switch, and the motion detector load lead will directly power two of eight potlights. The load lead will also be the power lead to the dimmer switch. The dimmer switch will control the remaining 6 potlights in the same room.

My questions are:
1) Will the fact that the motion detector be turning on and cutting power to the dimmer regularly whenever someone enters and leaves the room be a problem for the dimmer? will it wear it out or cause a malfunction?

2) Could the fact that the motion detector is driving two potlights directly and the dimmer switch be a problem for the motion detector switch reliability?

3) Could this introduce an audible ringing in the circuit?

Any help would be appreciated, Thanks.


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## 480sparky (Feb 1, 2009)

HandyMensch said:


> .......
> 
> My questions are:
> 1) Will the fact that the motion detector be turning on and cutting power to the dimmer regularly whenever someone enters and leaves the room be a problem for the dimmer? will it wear it out or cause a malfunction?


I don't see a problem there.



HandyMensch said:


> 2) Could the fact that the motion detector is driving two potlights directly and the dimmer switch be a problem for the motion detector switch reliability?


You may severely overload your motion sensor. What will determine this is the wattage rating of the motion switch. You're getting to where you really need a lighting contactor.



HandyMensch said:


> 3) Could this introduce an audible ringing in the circuit?


Depends on the dimmer and the bulbs you use. Cheap bulbs and cheap dimmers hum.


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## HandyMensch (Feb 3, 2009)

Thanks Sparky,

The motion switch is rated for 500 W, so I think that part should be OK. I was just wondering if anyone had heard of any weird type of interaction between them.

As a followup, 

1) have you ever heard of people using this type of configuration

2) can you explain why a cheap bulb would hum? What is going on in that?

3) Why do the cheap dimmers hum?

Thanks and regards


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## shanekw1 (Mar 20, 2008)

I can't figure out why you would want to do that.


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## 480sparky (Feb 1, 2009)

HandyMensch said:


> .....
> 2) can you explain why a cheap bulb would hum? What is going on in that?
> 
> 3) Why do the cheap dimmers hum?
> ...


 
Basically, lamps hum as the filament vibrates as power is turned on and off 120 times a second.

Dimmer can hum because they're electronic.

If you want to get technical, click here.


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## Eddy Current (Nov 19, 2006)

> I would like to connect a leviton motion detector light switch to a leviton dimmer switch which will control a bunch of potlights in a room in the basement.


They do make dimmable motion sensors. I've installed a crapload of them. Actually I have one in my truck right now. I can't remember the brand name, not Leviton, they come in a white box, very popular.

I'll get back to you on the model # etc.


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## Eddy Current (Nov 19, 2006)

The Watt Stopper
Dimmable PIR Wall Switch
Model # WD-270 (120volt)

--> http://www.wattstopper.com/products/details.html?id=15


Make sure the power is off when you install them. I had problems with some when connected live, support said they need a warm up period or something like that........oops, I mean I NEVER work live :whistling


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