faint flickering of CFL

[Ponchik]

I had a client complaining about faint flickering of the CFL when the switch is in the OFF position. So one of them had a dimmer and I know older CFLs with old slider dimmers do not go well together, so I suggested changing the bulb to incandescent or install a switch and that will solve the issue.

Now my question. Will phantom voltage create faint flickering when the switch is OFF on the CFL bulbs.
I have had this issue with ceiling fans and once we changed to incandescent the flickering went away or was not noticeable.


Thanks

 

[Dennis Alwon]

This is a common occurrence even with the dimmer switch off--A dimmer leaks a bit and causes this phenom. Put 1 incandescent in the mix and the flicker will stop

 

[LEO2854]

I had a client complaining about faint flickering of the CFL when the switch is in the OFF position. So one of them had a dimmer and I know older CFLs with old slider dimmers do not go well together, so I suggested changing the bulb to incandescent or install a switch and that will solve the issue.

Now my question. Will phantom voltage create faint flickering when the switch is OFF on the CFL bulbs.
I have had this issue with ceiling fans and once we changed to incandescent the flickering went away or was not noticeable.


Thanks

That will go away with a CFL/LED dimmer switch.

 

[cainisunabel]

If you go with a cfl dimmer, be sure to verify the lamp is dimmable or it won't do you much good.

Sent from my N861 using Tapatalk

 

[Ponchik]

Thank you for your posts.

I understand the non-compatible dimmer with non dimming CFL.

However, i am still fuzzy if phantom voltage will/may create faint flickering on the older CFLs.

Thanks

 

[GoldDigger]

Phantom voltage (capacitance from live to dead wires producing a high voltage with very low current drive, e.g high impedance) is not likely to cause flickering.
But the current form the electronics in the two-wire dimmer, which uses the load as a power return, can and does.

Tapatalk!

 

[kwired]

A dimmer that has a positive "open circuit" off position shouldn't allow any bleed through when in the off position.

That said I don't know a whole lot about this kind of detail of typical dimmer construction, as to whether or not there is a true open circuit when in the "off" position.

 

[AdrianWint]

We are seeing similar problems with LED/CFL here in the UK. The problem seems to be a little worse due to our higher voltage & our wiring methods leading to long runs of parallel switch wires.

The problems seems to mainly show itself on the staircase lighting which generally has two way switching (I think you guys across the pond call it three way? I'm referring to a light which can be switched on/off from more than one switching position). Such circuits tend to be wired using twin & earth cables (romex?) between the switching positions to carry both of the link wires between the switches (we call them 'strappers' or 'travellers'). Because these tend to be quite long & run parallel to each other they form a small a capacitor. It is my understanding that this capacitive effect allows a very small current to pass around the loop. This current, passing through the CFL/LED slowly charges the reservoir capacitor in the front end of its power supply. As the capacitor charges the voltage across it rises. When it rises to a critical point the CFL/LED will try to light, emitting a brief pulse of light. In doing so it discharges the capacitor & the whole cycle starts again. This is the explanation for the 'flickering/blinking' and also explains why putting a standard filament lamp in parallel stops this happening.

Another solution which seems to work well in the UK is to wire a small contact suppressor (0.1uF cap & 100R resistor is series) across the lamp - this gives the capacitive current an alternative path that isn't via the CFL/LED.

 

[GoldDigger]

:thumbsup:

Tapatalk!

 

[LEO2854]

We are seeing similar problems with LED/CFL here in the UK. The problem seems to be a little worse due to our higher voltage & our wiring methods leading to long runs of parallel switch wires.

The problems seems to mainly show itself on the staircase lighting which generally has two way switching (I think you guys across the pond call it three way? I'm referring to a light which can be switched on/off from more than one switching position). Such circuits tend to be wired using twin & earth cables (romex?) between the switching positions to carry both of the link wires between the switches (we call them 'strappers' or 'travellers'). Because these tend to be quite long & run parallel to each other they form a small a capacitor. It is my understanding that this capacitive effect allows a very small current to pass around the loop. This current, passing through the CFL/LED slowly charges the reservoir capacitor in the front end of its power supply. As the capacitor charges the voltage across it rises. When it rises to a critical point the CFL/LED will try to light, emitting a brief pulse of light. In doing so it discharges the capacitor & the whole cycle starts again. This is the explanation for the 'flickering/blinking' and also explains why putting a standard filament lamp in parallel stops this happening.

Another solution which seems to work well in the UK is to wire a small contact suppressor (0.1uF cap & 100R resistor is series) across the lamp - this gives the capacitive current an alternative path that isn't via the CFL/LED.

Good information :thumbsup:

 

[CT Tom]

Another solution which seems to work well in the UK is to wire a small contact suppressor (0.1uF cap & 100R resistor is series) across the lamp - this gives the capacitive current an alternative path that isn't via the CFL/LED.

I will have to experiment with this. On a job with ~200 lighting zones in a LiteTouch lighting system. Without talking to me, client changed the whole house out to CFL... Seeing as Litetouch is gone (now owned by Savant) this might be a stop-gap until they can upgrade.

 

[captainwireman]

I have a LED spot shining on the interior of my front door and a standard fluorescent controlled by one box store motion sensor. It is nice not to have to fumble around when you walk in the door and have the light go off when I go upstairs. The fluorescent works perfect, however; the LED bleeds and flickers in what appears to be a dimmed mode when the motion sensor is in the auto function. I left it this way as a sort of night light and it has worked for several years.

 

[kwired]

We are seeing similar problems with LED/CFL here in the UK. The problem seems to be a little worse due to our higher voltage & our wiring methods leading to long runs of parallel switch wires.

The problems seems to mainly show itself on the staircase lighting which generally has two way switching (I think you guys across the pond call it three way? I'm referring to a light which can be switched on/off from more than one switching position). Such circuits tend to be wired using twin & earth cables (romex?) between the switching positions to carry both of the link wires between the switches (we call them 'strappers' or 'travellers'). Because these tend to be quite long & run parallel to each other they form a small a capacitor. It is my understanding that this capacitive effect allows a very small current to pass around the loop. This current, passing through the CFL/LED slowly charges the reservoir capacitor in the front end of its power supply. As the capacitor charges the voltage across it rises. When it rises to a critical point the CFL/LED will try to light, emitting a brief pulse of light. In doing so it discharges the capacitor & the whole cycle starts again. This is the explanation for the 'flickering/blinking' and also explains why putting a standard filament lamp in parallel stops this happening.

Another solution which seems to work well in the UK is to wire a small contact suppressor (0.1uF cap & 100R resistor is series) across the lamp - this gives the capacitive current an alternative path that isn't via the CFL/LED.

makes perfect sense to me. Now place conductors in a field with higher voltages present and you can probably increase the charge rate and of course the flash interval. Any resistive load in parallel with the CFL/LED would shunt that charge current and solve the flash issue. In fact a higher quality device may very well have a shunt resistor built in for such purposes.