Capacitor for occasional LED lighting flicker

Thread Starter

lwalper

Joined Mar 1, 2020
2
I'm a newbie here so please be charitable.

For the last 25 years I've had trouble keeping the clock set on my microwave ovens at my church. Since they are in a low use area it will generally be a week between seeing the clocks and they are always reset to 000 from one week to the next like there has been a power interruption sometime that week. No other real electrical problems noted. Sound systems are on UPS so any power fluctuations are smoothed there. My question now is, the fluorescent lighting has been deteriorating requiring replacement ballast, bulbs, and etc so I decided to install LED tubes. I cut out the ballast and installed straight wired LED tubes -- no problem, they work great! However, they occasionally flicker for a few seconds and I suspect it is due to fluctuations in line supply. I have discussed this with my power supplier who say they have checked everything out and all is nominal from the supply side. (I find that hard to believe with my 25 year history). I believe the problem is intermittent and difficult to diagnose from their perspective. The transformer on the building is probably 50 years old, but they are loathe to replace it on a whim.

Now, my question: -- would a capacitor in the line smooth the supply to each of the LED bulbs allowing them to operate without the occasional millisecond flicker. If so, what capacitance should I install? I've got 16 tubes installed in one room and they all blink at the same instant, so I don't think it's a single tube power circuit problem. If a capacitor would solve the problem what value should I be looking for? 4' LED tubes.
 

cmartinez

Joined Jan 17, 2007
7,313
I'm a newbie here so please be charitable.

For the last 25 years I've had trouble keeping the clock set on my microwave ovens at my church. Since they are in a low use area it will generally be a week between seeing the clocks and they are always reset to 000 from one week to the next like there has been a power interruption sometime that week. No other real electrical problems noted. Sound systems are on UPS so any power fluctuations are smoothed there. My question now is, the fluorescent lighting has been deteriorating requiring replacement ballast, bulbs, and etc so I decided to install LED tubes. I cut out the ballast and installed straight wired LED tubes -- no problem, they work great! However, they occasionally flicker for a few seconds and I suspect it is due to fluctuations in line supply. I have discussed this with my power supplier who say they have checked everything out and all is nominal from the supply side. (I find that hard to believe with my 25 year history). I believe the problem is intermittent and difficult to diagnose from their perspective. The transformer on the building is probably 50 years old, but they are loathe to replace it on a whim.

Now, my question: -- would a capacitor in the line smooth the supply to each of the LED bulbs allowing them to operate without the occasional millisecond flicker. If so, what capacitance should I install? I've got 16 tubes installed in one room and they all blink at the same instant, so I don't think it's a single tube power circuit problem. If a capacitor would solve the problem what value should I be looking for? 4' LED tubes.
If the LED tubes work with AC, then a capacitor won't cut it, at least on the power line side. If you have access to the DC side feeding the LEDs, you might install a capacitor, but it would probably have to be of a very large value. Easiest and safest bet would be to use a UPS, although that would also be the most expensive. The flicker you're experiencing could be faulty wiring. Possibly some cable junction that heats up after a while and causes the intermittent behavior you're experiencing. It's probably best to hire an electrician to track the problem down, since you don't know if this small inconvenience might grow with time into a more serious issue.
 

Delta prime

Joined Nov 15, 2019
841
  • My charitable contribution is don't you dare think about capacitors at line level!! It will kill you and it will hurt the whole time you are dying!!

  • If the flickering and dimming seems to affect only one circuit then the circuit needs to be identified and all of the devices of that circuit, including light switches and the light fixtures.
  • These identified devices will all need to be checked starting with inspecting the junction box wiring of the ceiling light fixtures.
  • Ceiling light fixtures with standard incandescent light bulbs along with the ballast a fluorescent lighting create heat which can cause the wire spices inside the ceiling light fixture junction box to become brittle and deteriorate and cause intermittent circuit performance to the point of circuit failure, and in some cases this can even cause a fire
  • If you are located near a large city then you may be experiencing voltage levels that are dropping due to electrical loads on the utility grid.
  • An electric power recording meter may be installed on the main power line for a few days to record the levels of voltage and determine if adjustments are needed within the local utility grid.
  • Typically the local electric utility company will provide this service.
 
Last edited:

Thread Starter

lwalper

Joined Mar 1, 2020
2
Thanks for your prompt replies!!
  • My charitable contribution is don't you dare think about capacitors at line level!! It will kill you and it will hurt the whole time you are dying!!
  • Yep, that's why I'm here asking.
  • [*]If the flickering and dimming seems to affect only one circuit then the circuit needs to be identified and all of the devices of that circuit, including light switches and the light fixtures.
    [*]
  • No, separate circuits, different rooms.
  • [*]These identified devices will all need to be checked starting with inspecting the junction box wiring of the ceiling light fixtures.
    [*]Ceiling light fixtures with standard incandescent light bulbs along with the ballast a fluorescent lighting create heat which can cause the wire spices inside the ceiling light fixture junction box to become brittle and deteriorate and cause intermittent circuit performance to the point of circuit failure, and in some cases this can even cause a fire
    [*]If you are located near a large city then you may be experiencing voltage levels that are dropping due to electrical loads on the utility grid.
    [*]
  • No big cities nearby, but a 135-MW hydro facility is about 1 mile away. I was wondering about power ripple or something happening at the generator. Not so important with older analog equipment, but these newfangled digital things are a little more sensitive to that sort of stuff.
  • [*]An electric power recording meter may be installed on the main power line for a few days to record the levels of voltage and determine if adjustments are needed within the local utility grid.
    [*]
  • I've been thinking about getting a data logger for that purpose
  • [*]Typically the local electric utility company will provide this service.
I'll check with them for a data logger.
 

MisterBill2

Joined Jan 23, 2018
8,447
I'm a newbie here so please be charitable.

For the last 25 years I've had trouble keeping the clock set on my microwave ovens at my church. Since they are in a low use area it will generally be a week between seeing the clocks and they are always reset to 000 from one week to the next like there has been a power interruption sometime that week. No other real electrical problems noted. Sound systems are on UPS so any power fluctuations are smoothed there. My question now is, the fluorescent lighting has been deteriorating requiring replacement ballast, bulbs, and etc so I decided to install LED tubes. I cut out the ballast and installed straight wired LED tubes -- no problem, they work great! However, they occasionally flicker for a few seconds and I suspect it is due to fluctuations in line supply. I have discussed this with my power supplier who say they have checked everything out and all is nominal from the supply side. (I find that hard to believe with my 25 year history). I believe the problem is intermittent and difficult to diagnose from their perspective. The transformer on the building is probably 50 years old, but they are loathe to replace it on a whim.

Now, my question: -- would a capacitor in the line smooth the supply to each of the LED bulbs allowing them to operate without the occasional millisecond flicker. If so, what capacitance should I install? I've got 16 tubes installed in one room and they all blink at the same instant, so I don't think it's a single tube power circuit problem. If a capacitor would solve the problem what value should I be looking for? 4' LED tubes.
Short answer: NO!
An AC line flicker will not be cured by an AC line capacitor.
One simple choice would be to get a different microwave oven designed to not be bothered by such minor fluctuations.
If you have somebody competent to do it, opening each circuit breaker panel and tightening all of the terminals, especially the mains, is a good start. Note that this does involve access to areas with lethal voltages and so it must be a person who knows just what they are doing and is competent to do it. Some licensed electricians might qualify, but not all of them.
The same process can go all the way back to your building electrical meter, past tghat is the realm of the power company, so I recommend stopping at the meter. The process should also include such slices as there may be in the distribution system.
There are other ways to investigate, but this method takes only a few tools and a fair amount of time.
 
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