LED's & Microwave

[jmellc]

Recently installed cans in a friend's kitchen, using Sylvania LED trim. He called that lights were flickering with microwave or dishwasher running. I went over while they were gone & checked things out. I could only get them to flicker when mw starts, stops or boosts/bucks power. He said today that they have sometimes done a constant flicker for him when mw running, sort of a strobe look but he can't get them to do it again "on demand".

Has anyone else dealt with this? Any filters out there that may help?

Sylvania 3000K, 13 watt trim. Convertible & will fit into an octagon box.

Thanks for any feedback.

 

[GoldDigger]

Recently installed cans in a friend's kitchen, using Sylvania LED trim. He called that lights were flickering with microwave or dishwasher running. I went over while they were gone & checked things out. I could only get them to flicker when mw starts, stops or boosts/bucks power. He said today that they have sometimes done a constant flicker for him when mw running, sort of a strobe look but he can't get them to do it again "on demand".

Has anyone else dealt with this? Any filters out there that may help?

Sylvania 3000K, 13 watt trim. Convertible & will fit into an octagon box.

Thanks for any feedback.

This is the third (?) thread I have seen here on more or less the same subject. The consensus is that some LED dimmers are very sensitive to RFI on the wiring, created by other appliances. Line filtering at the source or switching to a different brand (or even just newer manufacture date) of the controls may both help.
Does this only happen when the LEDs are running at less than full output?

If the dishwasher is cord-attached, plugging in an inexpensive power line filter (not just a surge protector) is the quickest way to check for this and may even be a long term solution.

If there is no dimmer involved at all, then the same RFI may be messing with the drivers in the LED trim itself. But less likely.

 

[jmellc]

Thanks Gold Digger. These are not on dimmers. Dishwasher is hard wired to a wall switch. He has some basement cans on dimmers & said they acted strange but they did OK for me. I will get with my suppliers about any filters I could install but I think the blinking I saw is somewhat normal, as I have seen it with most types of lights when MW's or other heavy appliances crank up.

I have not installed a lot of LED lighting. I have priced a lot of projects I didn't get. I have not "gotten the feel" of LED's yet.

 

[cadpoint]

P=IE

If One remembers that LED work in a chopped sign wave created by the diode, and recall that most other devices usually work with inrush, I can see the problem.

I beleive one chops the voltage and the other device the current, thus one is causing a lack of a summary that the other equipment is seekng.

The Microwave enjoy's peak power the LED is depriving

 

[jmellc]

If $ were no object, I would split the service into 2 panels, dual feeds from meter, and put the lights & computers on a panel together, general power on the other. But even that may not help much, as the same line feeders supply both panels.

 

[weressl]

Recently installed cans in a friend's kitchen, using Sylvania LED trim. He called that lights were flickering with microwave or dishwasher running. I went over while they were gone & checked things out. I could only get them to flicker when mw starts, stops or boosts/bucks power. He said today that they have sometimes done a constant flicker for him when mw running, sort of a strobe look but he can't get them to do it again "on demand".

Has anyone else dealt with this? Any filters out there that may help?

Sylvania 3000K, 13 watt trim. Convertible & will fit into an octagon box.

Thanks for any feedback.

Sounds like problem with the LED power supply. Low voltage when motors get cranking? Swicth to different circuit, upsize wiring?

 

[jmellc]

Sounds like problem with the LED power supply. Low voltage when motors get cranking? Swicth to different circuit, upsize wiring?

Lights & MW are already on different phases in the panel. I checked for that. I have seen many lights blink when MW starts, stops or "changes gears". More obvious with the LED's though.

 

[kwired]

Lights & MW are already on different phases in the panel. I checked for that. I have seen many lights blink when MW starts, stops or "changes gears". More obvious with the LED's though.

They do that because of voltage drop. When the magnetron in the MW is energized it is an inductive load and has an inrush current just like other inductive loads.

As has been said an LED is operating on rectified current, so only half the voltage of the sine wave, which means a drop in voltage on the full wave is even more percentage of normal at half wave voltage.

 

[jmellc]

With voltage drop being an issue, I don't suppose any kind of filters would help? Has anyone tried filters?

My bigger concern too is that microwaves are here to stay and LED lights are the up and coming thing. If microwaves interfere, other equipment in commercial/industrial locations will undoubtedly do the same. Are LED's such a good thing after all? Or is work being done to make them less prone to interference? Is this going to become a bigger and bigger issue? Remember too, people are more spoiled than ever before. No one wants a light to blink when something else operates.

 

[kwired]

Filters for voltage drop include larger supply conductors and/or bigger power supplies with less internal impedance. Stepping up voltage and stepping back down near the load also works, and is kind of what power transmission and distribution is all about.

 

[jmellc]

Filters for voltage drop include larger supply conductors and/or bigger power supplies with less internal impedance. Stepping up voltage and stepping back down near the load also works, and is kind of what power transmission and distribution is all about.

Bigger power supplies for manufactured lights would be major surgery and expense, if I can even get them. So would increasing wire size after the fact. Ceiling is full of insulation, 2 feet deep. Was a hard enough job the first time around. Remodel cans, some would have to come out, be reconnected, reinstalled. They are a pain 1st time, with the clips they use. 2nd time is even worse. All this and no certain result is not a doable option.

I MIGHT be able to install transformers just past switches (3 and 4w switches) and just before lights. Would mean 4 tsf, as I have 2 switch legs to lights. Would I try a 120/240 txf after switch and a 240/120 txf just before the lights? Has anyone tried something like this? I am doubting whether it would work. I still think lights would blink, as MW would still cause starting voltage to drop & secondary would drop for same period of time.

 

[kwired]

Bigger power supplies for manufactured lights would be major surgery and expense, if I can even get them. So would increasing wire size after the fact. Ceiling is full of insulation, 2 feet deep. Was a hard enough job the first time around. Remodel cans, some would have to come out, be reconnected, reinstalled. They are a pain 1st time, with the clips they use. 2nd time is even worse. All this and no certain result is not a doable option.

I MIGHT be able to install transformers just past switches (3 and 4w switches) and just before lights. Would mean 4 tsf, as I have 2 switch legs to lights. Would I try a 120/240 txf after switch and a 240/120 txf just before the lights? Has anyone tried something like this? I am doubting whether it would work. I still think lights would blink, as MW would still cause starting voltage to drop & secondary would drop for same period of time.

If the voltage drop is on the service or feeder nothing you do to the branch circuit will make any significant difference outside of changing the load itself or adding some type of storage device able to ride through the surge. Otherwise if the voltage drops before it gets to a specific point in the circuit anything done to try to boost it will essentially end up creating even more drop. Now you could fine tune for a specific fixed load, but for general purpose variable loads best results are larger supply components that will prevent having the drop in the first place.

 

[jmellc]

If the voltage drop is on the service or feeder nothing you do to the branch circuit will make any significant difference outside of changing the load itself or adding some type of storage device able to ride through the surge. Otherwise if the voltage drops before it gets to a specific point in the circuit anything done to try to boost it will essentially end up creating even more drop. Now you could fine tune for a specific fixed load, but for general purpose variable loads best results are larger supply components that will prevent having the drop in the first place.

I am still not clear on this when the MW in on phase A & lights on phase B. Momentary surge of current affecting the lights I can see. Voltage drop, I don't see. Seems like voltage drop would only be a real issue if they are on the same circuit or same phase.

I hate the ides of having to run #12 for lights. Switch boxes are already crowded enough, especially since having to put a neutral in every box. Imagine the issue with a couple of 12/3 cables instead of 14/3. Can lights have limited space in their wiring boxes too. I would have to install more junction boxes in hard to get to places in attics and/or crawl spaces. Add in the bulky dimmers people often want to use and get chaos.

Maybe LED's are not such a good idea after all?

 

[kwired]

I am still not clear on this when the MW in on phase A & lights on phase B. Momentary surge of current affecting the lights I can see. Voltage drop, I don't see. Seems like voltage drop would only be a real issue if they are on the same circuit or same phase.

I hate the ides of having to run #12 for lights. Switch boxes are already crowded enough, especially since having to put a neutral in every box. Imagine the issue with a couple of 12/3 cables instead of 14/3. Can lights have limited space in their wiring boxes too. I would have to install more junction boxes in hard to get to places in attics and/or crawl spaces. Add in the bulky dimmers people often want to use and get chaos.

Maybe LED's are not such a good idea after all?

Depends on where the voltage drop is occurring. If the transformer is where the drop is, then it may not matter that the microwave is on A and the light is on B, both may be experiencing the drop because the drop is across the entire transformer

 

[jmellc]

Depends on where the voltage drop is occurring. If the transformer is where the drop is, then it may not matter that the microwave is on A and the light is on B, both may be experiencing the drop because the drop is across the entire transformer

That is encouraging. To use LED lights and microwave in the same house, maybe POCO can set a 2nd txf at the house and feed 2 service drops in for 2 meters and 2 panels. If it goes further back than the pole txf, maybe they can run a 2nd line from a 2nd generator?

I know this is crazy, I am just carrying things out to their likely conclusion. IF LED's and microwaves are not compatible, either LED's need a lot more refining or should not be installed. If the issue goes to an outdoor transformer, LED's are simply not worth doing. Seems like the customer and I could both spend a fortune here and still not get good results.

 

[kwired]

That is encouraging. To use LED lights and microwave in the same house, maybe POCO can set a 2nd txf at the house and feed 2 service drops in for 2 meters and 2 panels. If it goes further back than the pole txf, maybe they can run a 2nd line from a 2nd generator?

I know this is crazy, I am just carrying things out to their likely conclusion. IF LED's and microwaves are not compatible, either LED's need a lot more refining or should not be installed. If the issue goes to an outdoor transformer, LED's are simply not worth doing. Seems like the customer and I could both spend a fortune here and still not get good results.

I don't know for certain what your problems are, but we started to go down the voltage drop road. If the service in your case is supplied by overhead conductors and multiple services are supplied they are often complicated by small conductors or small transformers, this has been a problem long before LED's came about, but there could be other issues causing your problems also.

 

[ggunn]

...I know this is crazy, I am just carrying things out to their likely conclusion. IF LED's and microwaves are not compatible, either LED's need a lot more refining or should not be installed. If the issue goes to an outdoor transformer, LED's are simply not worth doing. Seems like the customer and I could both spend a fortune here and still not get good results.

Another option is to just live with the LED flicker when the microwave is running. It's an imperfect world.

 

[mgookin]

All of this discussion assumes the microwave is in good working order. Is it? Can you swap it out for another and see if it still happens? The OP says it's a friend's house.

 

[GonzaloGomez]

LEDs in the Kitchen

LEDs in the Kitchen

I have LEDs (Cree CR-6) in my 6 in cans in my kitchen and do not see these issues. It might be this brand Sylvania.

LED power supplies will vary between manufacturers and some may be more forgiving than others.

Also, it is not unheard of to have microwave ovens interfere with other devices (telephones, TV's, etc). And the dishwasher could have a marginal motor.

 

[jmellc]

Another option is to just live with the LED flicker when the microwave is running. It's an imperfect world.

I have told him this is probably what he will have to do, that I will try whatever means is easily available.