Incandescent dimmer on Magnetic Lo Vo fixture

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Sierrasparky

Sierrasparky

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Location
USA
Occupation
Electrician ,contractor
I was wondering can a Incandescent dimmer ( lutron maestro) on a Low Voltage Mr-16 fixture cause the transformer to burn out?
I found a burned out Maestro and some of the lo Vo fixtures had burned our transformers.
 
090909-1251 EST

A standard phase shift type dimmer may not provide a balanced volt-time integral waveform to a load. If the load is a ferromagnetic (iron core) transformer, then this unbalanced integrated voltage waveform will drive the core more into saturation on one half cycle than the other and cause higher magnetization current and thus may burn the transformer out. This is somewhat the same as putting a single diode in series with the transformer primary but may not be as severe.

Check with the transformer manufacturer for a suitable dimmer.

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Here's my thought:

I would think it is apparent that if several xfmrs are burned out, then it's likely the dimmer is the culprit(going on the info you provided). My question is- is it a packaged unit? The theory would have already been done, and they may be defective. If not, then we may be looking at a VA issue, since the dimmer changes what the xfmr receives and it may need this constant in order to operate at top efficiency (operating at less than full load decreases the efficiency). Could installing the dimmer on the load side of the transformer solve it?

Looks like gar hit the nail on the head.
 
The fixtures are Halo Lo vo MR-16, not all the transformers seem to be dead.
 
Also the dimmer was blown. I had heard it was working for several years. Also in a room not used very much at all.
 
Gar's last line is the most important. Check for listed compatibility.

We had a fireplace with a blower used for the heat exchange. The builder used a regular ol' dimmer switch to control the motor. It worked fine for years (occasional use) and as suspected, the motor burned up.

This was a 300 dollar (just parts) failure that could have been prevented by proper design.

To make things even worse, the person that did the solid oak trim around the fireplace covered the dimmer plate with decorative oak which will have to be removed in order to change out the dimmer. Way more than 300 bucks for that.

So far, the expense hasn't been justified so the repair did not get made.
 
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