LED lamps

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DHkorn

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In my home I have a couple of lighted 3-way switches and a lighted four way controling 8 lighting outlets (no dimmers). Four are reccessed cans and four are sconces. The sconces each have two candalabra bases. I decided to replace my compact flourescent lamps, working fine for a few years or so, with new LED types. When I changed the lamps in the sconces two things happened: when the switches were on everything was fine. When the switches were off the largest compact flourescent lamp will dimmly alternate on and off and the LED lamps were lighting dimly steady. Also when the switches are off they are not lighting like they should. There was no warning on the lamp package regarding use with lighted switches; which is were I'm guessing the issue is. Question one: It is the lighted switches causing the problem, right? Has anyone else seen this? And question two: is it a fire hazard? The LED bulbs seem to have a PC board or something like a ballast at the base.
Thanks. I Love this forum.
 
You problem is the lighted switches and the LED lamps. A lighted switch (lighted when OFF), leaks current through the load in order to illuminate it. This current is limited by the resistance of the small light in the switch. A normal light bulb does nothing when that small current flows through it. A CF probably won't light up either with this piddling current. But LEDs hardly need any current at all.

I have some LED christmas lights I tried to control with an X10 switch, and they do the same thing -- leaks enough current that you can easily see these lit up a bit at night.

Whether this will shorten the life of the LED lamps, I don't know. I also don't know if it is a fire hazard. I doubt it, but I don't know how the LED ballast works.
 
The "ballasts" are called "drivers" and are essentially constant current or constant voltage DC power supplies, depending on the application.
 
DHkorn said:
Question one: It is the lighted switches causing the problem, right? Has anyone else seen this? And question two: is it a fire hazard? The LED bulbs seem to have a PC board or something like a ballast at the base.
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What a great set of questions.

Sorry that you've got the problem, but, hey, I think you've stumbled onto another of the limitations of the current iteration of CFL electronic ballasts and LED exciters.

This sounds like a very interesting interaction, and I hope we can develop a better understanding of what the hardware is doing.

First question back to you. Are the illuminated switches ones without neutrals, and the light is on only when the load is "off"?

First trouble shooting suggestion. Replace one or two switches with non-illuminated, and note changes in the "off" behavior of the LEDs & CFLs.
 
I just 'googled' lighted 3-way and 4-way switches, some of them are not made to be

swapped with 'normal' 3-way,4-way wiring, some are. Think about it, you change one sw,s

position and the lights in 2 or 3 other switches come on and off in thr correct manner ?

That's pretty good.
 
And this is why having a neutral run to switches is a good idea and gets to be a better idea as time goes on and CFLs and LEDs become more prevalent.

The reason the CFL flashes is that an (electronic) CFL lamp works just like a switched mode power supply in a computer or whatever. The mains terminals are connected to a bridge rectifier which is followed by a capacitor.

The neon lamp and its associated resistor in the lighted switch passes a small amount of current which charges the capacitor in the CFL. When the electronics in the CFL detect the voltage across the capacitor is sufficiently high the inverter starts and powers the lamp, which lights up. Immediately the lamp comes on the capacitor is discharged and so the light goes out. Cycle repeats.
 
DK, you might try an incadescent along with the other lights to see if that returns any normal behavior. If it does, maybe you could connect it somewhere hidden.

The lights in multiple lighted switches are basically in parallel when the load is switched off. If their firing voltages differ, one or more may not light properly.
 
benaround said:
Larry,

In parallel useing a grounded conductor or just the switching terminals??
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The latter.

When a switch is open, the line voltage is seen across the switch terminals if the load is capable of passing the voltage through it.

That's one way I test for an open fuse, too.
 
Thanks all.
No I do not have a nuetral for the switches. They're the standard Leviton (lighted when off) type.
The biggest issue I have with the LED's (beyond the safety issue) is not having the switches lighted when off and the steady dim glow.
But no one nows if there is any testing or documentation on LED's (or low current lamps) and lighted switches?
Is any testing done to address this issue when they are listed?
The life cycle of lamp technology seems to be about 2 years lately. Seems like as the lamp loads get smaller it will become an issue for more of us.
 
DHkorn said:
They're the standard Leviton (lighted when off) type.
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OK. The three switches (2 - 3ways & 1 - 4way) will have their lights hooked between the travelers, so the three indicator lights will be in parallel to each other when the switches have the luminaires off.

By changing the sconce CFLs to LEDs, I suspect that the overall impedance of all the CFLs and LEDs rose just enough that the voltage across the luminaire impedance (all the CFLs and LEDs in parallel) is just high enough that not enough is left for the switch indicator lights.

Follow up on Larry's suggestion about an incandescent lamp. Try replacing any one lamp in any of the luminaires with an incandescent of comparable light output.

The incandescent lamp resistance will be so low, by comparison to the CFLs and LEDs, that, when in parallel with the CFLs and LEDs, will drag the overall impedance way down.
 
If these illuminated Leviton switches are still lit with little neons (which I suspect they are), I'll bet that we'll see Leviton shift them to LEDs in the near future.
 
dbuckley said:
And this is why having a neutral run to switches is a good idea and gets to be a better idea as time goes on and CFLs and LEDs become more prevalent.

The reason the CFL flashes is that an (electronic) CFL lamp works just like a switched mode power supply in a computer or whatever. The mains terminals are connected to a bridge rectifier which is followed by a capacitor.

The neon lamp and its associated resistor in the lighted switch passes a small amount of current which charges the capacitor in the CFL. When the electronics in the CFL detect the voltage across the capacitor is sufficiently high the inverter starts and powers the lamp, which lights up. Immediately the lamp comes on the capacitor is discharged and so the light goes out. Cycle repeats.
Click to expand...

Very interesting insights dbuckley.
I was aware of LEDs lighting dimly due to small leakage currents but had never thought about CFLs.

Thanks for your post as it got me thinking and experimenting.

This peaked my interest so I tried a neon bulb(with 47K ohms in series) in series with two different types of CFL lamps (one at a time).
One CFL did nothing while the neon lamp lit just fine.

The second CFL pulsed on/off very dimly at about a 0.5hz just as you described. The neon lamp glowed as expected.

From what I have read CFLs have a few different drive circuit types and it appears some are more likely to exhibit the dim flashing behavior than others.
 
ELA said:
From what I have read CFLs have a few different drive circuit types and it appears some are more likely to exhibit the dim flashing behavior than others.
Click to expand...
I stalled a 23w CFL in a PC-equipped exterior light for my mom. The light blinked about once per second all the time when off.
 
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