Dimmers make induction cooktop buzz

[brantmacga]

I had some guys install Satco LED recessed lighting recently in a home. The customer called a couple of days later saying that all of the lights were flickering when dim, so I sent them back with different dimmers to replace.

Providing all details in case they are relevant.....


The customer called again and said they still had a problem, so I went out today to have a look. Whenever they turned on the A/C or cooktop, all would flicker slightly and dim down. For that particular issue, I found that almost every lug in the neutral bar was extremely loose; torquing everything in the panel solved the dimming issue, but one can light would flash when the cooktop was on; I removed the thermal cutout as a test, and that solved the flashing of that LED.

So the issue I found they didn't even mention was that when the lights and induction cooktop are both on, there is a terrible buzz coming from the cooktop, and adjusting the dimmer changes the tone of the buzz. Turn the lights off and it stops completely.

The dimmers are Lutron Adriadni C-L; it looks like these are forward phase dimmers, so my only other thought right now is to try reverse phase dimmers. I'm at a loss here ....

My supplier did send me Lutron Diva C-L dimmers to try for the flashing at the recommendation of Lutron, but I did not install them because the technology seems to be the same.

Edit to add..... I did a search earlier and found a discussion here on someone having the same problem with incandescent lighting, but I did not see a resolution to their problem either.


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[GoldDigger]

I had some guys install Satco LED recessed lighting recently in a home. The customer called a couple of days later saying that all of the lights were flickering when dim, so I sent them back with different dimmers to replace.

Providing all details in case they are relevant.....


The customer called again and said they still had a problem, so I went out today to have a look. Whenever they turned on the A/C or cooktop, all would flicker slightly and dim down. For that particular issue, I found that almost every lug in the neutral bar was extremely loose; torquing everything in the panel solved the dimming issue, but one can light would flash when the cooktop was on; I removed the thermal cutout as a test, and that solved the flashing of that LED.

So the issue I found they didn't even mention was that when the lights and induction cooktop are both on, there is a terrible buzz coming from the cooktop, and adjusting the dimmer changes the tone of the buzz. Turn the lights off and it stops completely.

The dimmers are Lutron Adriadni C-L; it looks like these are forward phase dimmers, so my only other thought right now is to try reverse phase dimmers. I'm at a loss here ....

My supplier did send me Lutron Diva C-L dimmers to try for the flashing at the recommendation of Lutron, but I did not install them because the technology seems to be the same.

Edit to add..... I did a search earlier and found a discussion here on someone having the same problem with incandescent lighting, but I did not see a resolution to their problem either.


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Wow. Apparently the dimmers are putting some electrical trash on the feed to the cooktop that is interacting badly with the phase control electronics of the cooktop itself.
This would be most understandable if there was still a problem with the neutral to the cooktop and the dimmer circuit was actually significantly changing the waveform seen by the cooktop.
Is the cooktop 240 but with a neutral connection? Is is a four wire feed or is there a ground to neutral jumper in place inside it? Is it cord fed or hard wired?
The very first thing I would do is check out the integrity of the cooktop neutral, measuring the voltage from it to the EGC as you operate the dimmed lights.

 

[Dennis Alwon]

I would try a different brand bulb such as phillips.... I bet that is the issue but I don't know why...LOL

 

[GoldDigger]

I would try a different brand bulb such as phillips.... I bet that is the issue but I don't know why...LOL

We know that some LED bulbs, even without a dimmer present, emit a lot of RF energy.
Possibly that is getting into the cooktop controls. Similar to the way strong RF can trip some GFCI and AFCI breakers.
Far fetched? Maybe not.
If that is the mechanism, a line filter to keep conducted RF out of the cooktop might make the difference.

 

[brantmacga]

Satco says most all of these LED trims are made across 3 factories in China and stamped with different brand names.

Lutron wants me to try another dimmer with a certain date code, and also an RF filter. Can anyone point me to a 120v line filter ?

Thanks


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[gadfly56]

Satco says most all of these LED trims are made across 3 factories in China and stamped with different brand names.

Lutron wants me to try another dimmer with a certain date code, and also an RF filter. Can anyone point me to a 120v line filter ?

Thanks


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A quick look got me here. But Yikes! at $370 it ain't cheap.

 

[GoldDigger]

A quick look got me here. But Yikes! at $370 it ain't cheap.

That is definitely overkill for the OP's situation.
Some of the filters here are more likely to be appropriate and they cost a lot less. But they will have to be mounted in a device box, not just packed into a junction box.

Did Lutron suggest filtering the lighting circuit, the cooktop, or both?

 

[brantmacga]

Did Lutron suggest filtering the lighting circuit, the cooktop, or both?

The lighting only, and they suggested that I could install an incandescent lamp in the attic between the dimmer and first can as a filter. I'd like to not do that.


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[mgookin]

Lutron should spec (and maybe even supply) these parts. They should have all the testing done to know what works to fix THEIR problems! You shouldn't have to go through time and cost to figure out what does and does not work.

 

[Dennis Alwon]

Take one light with the led and replace it with an incandescent -- that should work. Are we correct in assuming these are line voltage fixtures and not low fixtures?

Again I would pull the trims out and try a phillips LED bulb temporarily and see what happens. Remember a 600 watt c/l dimmer is only good for 150 watt led

 

[mgookin]

I may have erred in post #9. Lutron makes the dimmer and the bulbs are the culprit?

Too many people spend too much time on this issue. Time is money and it ends up with unhappy customers. Nobody wants to hire a pro and have problems with the work they spent good money on, even though they do come back and fix it.

What would it take to solve this problem?

Don't we already have manufacturer's of LED lights saying what dimmers work with their products? Is that the answer? Only buy lights that have a statement that they work with certain dimmers?

Carry one of each type of dimmer on the truck?
Filters too?

 

[brantmacga]

Don't we already have manufacturer's of LED lights saying what dimmers work with their products? Is that the answer? Only buy lights that have a statement that they work with certain dimmers?

Carry one of each type of dimmer on the truck?
Filters too?

The dimmers we have are listed as compatible on the LED manufacturers website. Lutron asked me to try another dimmer though with a newer date code.


Dennis I have 45w of LED on one dimmer, and 36w on the other.


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[ghostbuster]

A recent I.E.E.E. article indicated lighting dimmers in one house were causing the nearby multiple neighbours remote controlled garage doors to malfunction.Changed dimmer to switch and all problems were solved.

 

[brantmacga]

This one has been solved .... installed Diva C-L dimmers generation 3.0 and it stopped the humming sound.


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[Electric-Light]

LaGrand offers TruUniversal intended to work with all but 0-10v and 3-wire (that uses switched hot and a separate dimmed hot) system, which is like $60.

It has the option to select between forward and reverse phase. Some LED ballasts and ELVs operate with reverse and forward phase, but the LED ballast for home use emphasize on forward phase compatibility as it is the dominant, cheaper technology. It prevents the noise by letting the current rise on its own and dimming by cutting the flow instead. You should always have one sitting around for troubleshooting purpose.

The only solid rule you should stick by is to not use reverse phase with inductive loads like fans, magnetic low voltage transformer.