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Old 02-16-2009, 08:19 PM   #1
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Blowing Dimmer and Voltage Variation


I have installed new wiring for additional floodlights around my house. On my Patio, I have (2) 200watt halogen fixtures tied together and then dropped into a 3 switch box on my wall. I installed my dimmer (Lutron 600w for halogens), switched the power on at breaker, came back in and turned on the dimmer to check out my new lights and about 5 seconds after switchiong on - boom - blew the dimmer.

Next day bought new dimmer and had exact same results.

I checked voltage on the 3 hot legs in the box as follows: 123V (dimmer leg), 110v switch #2, and 96V, switch #3.

Somethings not right in Tinseltown.

Was pretty careful pulling wires and used plastic junction boxes. Anyone have a general idea whats going on here? Is there a way I can track down the prblem using a meter (and how)?

Thanks for anyone who replies.

Steven
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Old 02-16-2009, 08:42 PM   #2
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Blowing Dimmer and Voltage Variation


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turned on the dimmer to check out my new lights and about 5 seconds after switchiong on - boom - blew the dimmer.

Next day bought new dimmer and had exact same results.

I checked voltage on the 3 hot legs in the box as follows: 123V (dimmer leg), 110v switch #2, and 96V, switch #3.
If you substitute a piece of wire for the dimmer do the lights go on full brightness and the breaker holds?

96v with respect to ground? Measured with what kind of meter?

Last edited by Yoyizit; 02-16-2009 at 08:59 PM.
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Old 02-16-2009, 09:03 PM   #3
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Blowing Dimmer and Voltage Variation


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96v with respect to ground? Measured with what kind of meter?
From the hot wire to the switch leg hot wire. I guess I could have measured it against the ground also. I am using a standard volt meter set to read up to 200V.

Quote:
If you substitute a piece of wire for the dimmer do the lights go on full brightness and the breaker holds?
Or could I use a standard switch?

Does continuity testing or Ohm testing hold a purpose here?
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Old 02-16-2009, 09:14 PM   #4
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Blowing Dimmer and Voltage Variation


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From the hot wire to the switch leg hot wire. I guess I could have measured it against the ground also. I am using a standard volt meter set to read up to 200V.



Or could I use a standard switch?
Yes

Does continuity testing or Ohm testing hold a purpose here?
Not yet
Put an 120v incand. lamp across the 96v and see if the voltage stays at 96v.
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Old 02-16-2009, 09:49 PM   #5
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Blowing Dimmer and Voltage Variation


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Put an 120v incand. lamp across the 96v and see if the voltage stays at 96v.
Light did not turn on and the voltage across the plug head was 88V. I checked the hot wire and it was 123 to ground. Looks like I have something screwed up or damaged in my switch legs?

The dimmer that keeps blowing is 123V across the switch.
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Old 02-16-2009, 10:07 PM   #6
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Blowing Dimmer and Voltage Variation


Is this a 3 way setup?
Post what you think is the schematic or maybe you can find it on
http://en.wikipedia.org/wiki/Switch

I don't understand that 88v with a lamp load on it.
The test lamp might have been in series with the controlled lamp. If so, a 100W test lamp and a 100W controlled lamp should each have 60v across them.

Is the switch able to light the controlled lamps?

Last edited by Yoyizit; 02-16-2009 at 10:11 PM.
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Old 02-16-2009, 10:17 PM   #7
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Blowing Dimmer and Voltage Variation


Its a single pole setup all set on 12/2 Romex and in a 3 switch wall box.

Switch #1 = Dimmer tied to (2) 200W Halogen Flood Lights (twin 100W Halogen bulbs) for a total of 400W full on

Switch #2 = Single pole switched to single 300W Halogen Flood light

Switch #3 = Single pole switched to (2) 300W Halogen Flood lights

Its a pretty straight forward set-up. All commons tied together and wire-nutted. All grounds are in place and grounded back to the ground rod through the breaker box. Each switch has (1) live wire carrying 120V and 1 switch leg to the fixture.

When I tets Switch #1 wiring live-switch it is 123V. Switch #2 is less and switch #3 is down to 96V. I took a lamp and hooked the live leg and switch leg to the holes in the plug. Testing the exposed plug, it read 88V across the plugs prongs and the light never lit up. Maybe I did this wrong, but I would have thought the light would have come on, but dimmer at a low voltage.
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Old 02-16-2009, 10:52 PM   #8
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Blowing Dimmer and Voltage Variation


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Originally Posted by briggss` View Post
Its a single pole setup all set on 12/2 Romex and in a 3 switch wall box.

Switch #1 = Dimmer tied to (2) 200W Halogen Flood Lights (twin 100W Halogen bulbs) for a total of 400W full on

Switch #2 = Single pole switched to single 300W Halogen Flood light

Switch #3 = Single pole switched to (2) 300W Halogen Flood lights

Its a pretty straight forward set-up. All commons tied together and wire-nutted. All grounds are in place and grounded back to the ground rod through the breaker box. Each switch has (1) live wire carrying 120V and 1 switch leg to the fixture.

When I tets Switch #1 wiring live-switch it is 123V. Switch #2 is less and switch #3 is down to 96V. I took a lamp and hooked the live leg and switch leg to the holes in the plug. Testing the exposed plug, it read 88V across the plugs prongs and the light never lit up. Maybe I did this wrong, but I would have thought the light would have come on, but dimmer at a low voltage.
Anything else on this same circut, on the feed side.?
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Old 02-16-2009, 11:20 PM   #9
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Blowing Dimmer and Voltage Variation


No. That's all thats on the 15 amp breaker.
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Old 02-16-2009, 11:30 PM   #10
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Blowing Dimmer and Voltage Variation


Well now I know why my wife didnt want to move to Tinseltown.
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Old 02-16-2009, 11:36 PM   #11
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Blowing Dimmer and Voltage Variation


I guess tomorrow I'll have to take the fixtures down and look to see if something was pinned or damaged during the install. If not there, maybe its in the junction box in the attic. It sure sounds like a short soemwhere.

I don't get the voltage drop across the switch legs.
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Old 02-16-2009, 11:38 PM   #12
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Blowing Dimmer and Voltage Variation


What style dimmer is the lutron you have?
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Old 02-16-2009, 11:46 PM   #13
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Blowing Dimmer and Voltage Variation


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Light did not turn on and the voltage across the plug head was 88V. .
If you have a dimmer made for only inductive loads it wont work with a resistive load like a 60w light bulb.

Normal light dimmers are designed to only dim non-lunductive loads like light bulbs and electric [COLOR=blue! important][COLOR=blue! important]heaters[/COLOR][/COLOR]

. Normal light dimmers are not suitable to dim inductive loads like transformers, fluorescent lamps, neon lamps, halogen lamps with transformers and electric motors. There are special dimmers available for those applications.

If you connect inductive loads to the dimmer the dimmer might not work as expected (for example does not dim that load properly) and can even be damaged by the voltage surges generated by the inductive load when current changed radiply. Another problem is the phase shift between the voltage and current cause by the inductance. If you use a normal simple light dimmer which is just in series with the wire going to the load, this will cause that the dimmer circuit will not work properly with highly inductive loads. Special dimmers which have a separate controlling electronics connected to both live and neutral wire and then the triac which controls the current to the load usually work much bettter with inductive loads. Often when inductive loads cause problems on normal dimmers, you can eliminate said problems by patching an incandescent "ballast" load in parallel with the inductive load. Usually 100W is enough for many inductive loads. Remeber that indictive loads can hum quite noticably when dimmed and the transformers can heat more because of increased harmonics content in the power coming to them.
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Old 02-17-2009, 09:40 AM   #14
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It is a Lutron Skylark S-600P http://www.lutron.com/skylark/?s=17000&t=17200

On the box and on the switch tag it says it is intended for use with incandescent or halogen lighting. The lights are called Light Concepts by Lithonia and they each use (2) 100W quartz halogen bulbs. http://www.lightingdirect.com/index....g&cse=shopping

The incandescent test was done with no dimmer. The light's cord was directly connected to the feed and the switch leg.

The dimmer keeps blowing regardless of the switch load. The last time it blew, it was about 5 seconds after I turned on the rocker toggle and I never moved the slide.
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Old 02-17-2009, 10:32 AM   #15
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It is a Lutron Skylark S-600P http://www.lutron.com/skylark/?s=17000&t=17200

On the box and on the switch tag it says it is intended for use with incandescent or halogen lighting. The lights are called Light Concepts by Lithonia and they each use (2) 100W quartz halogen bulbs. http://www.lightingdirect.com/index....g&cse=shopping

The incandescent test was done with no dimmer. The light's cord was directly connected to the feed and the switch leg.

The dimmer keeps blowing regardless of the switch load. The last time it blew, it was about 5 seconds after I turned on the rocker toggle and I never moved the slide.
I'm sure you saw that the web site shows your dimmer as incandescent, but you said it was both, so that shouldnt be a prob. You are using the dimmer for outside lighting correct? Have you tried a indoor hal bulb to see if there is a difference then, it could be that the outdoor lighting is not made for dimming. I never tried to dim outdoor lighting before, do you have this setup else where on the house with good luck?
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