Using illuminated switch to control LED lights.

[sidwelle]

When using an illuminated light switch to control lights, When the switch is open the neon bulb is across the open switch allowing a very small current draw across the load to illuminate the neon lamp in the switch. Using a incondecient or halogen bulb as the load would not present a problem, but now using a LED bulb that runs on a lower current to begin with, and a circuit to control the LEDs, and/or the LEDs of the bulb will experience a constant voltage with the switch open or closed.

QUESTION: Will this significantly reduce the life of the LED bulb ?

Thanks

[gfretwell]

I am not sure it would hurt the lamp but there is a chance it will flash randomly.

[Dean Hoffman]

Would adding some sort of 120 vac flashcube relay to the load do any good?

[sidwelle]

Yes, a relay would solve it, but that's another part to fail. I wanted to keep this as simple as possible

[Dean Hoffman]

I work on irrigation systems. How about a suppressor? We see those "everywhere". The ones I'm thinking of look like a little box with black and white lead coming out. Failure are almost unheard of.

[gfretwell]

This problem is really not going to go away until the installations catches up to the code and we get a neutral at every switch location. Then you can use a 3 wire device.

[trader_4]

I don't see any mechanism where the Led bulb would be harmed. Worst case typical ones are cheap if somehow it did. But it will probably flicker or light dimly, which is typically the undesirable effect.

[sidwelle]

suppressor: can u provide a picture or link to one?

[trader_4]

What is a surge suppressor going to do for him?

[gfretwell]

A small resistor across the load would fix the problem and it might work as small as 100k ohms if this is just a neon. (1.2 ma)

[Clare Snyder]

No. It is current that kills LEDS and the current drawn by the indicator is insignificant

[Clare Snyder]

I use 2 40 watt equivalent LED bulbs on one circuit with a lighted switch - no problem. No flash, no flicker. On 3 other circuits I have single 70 watt equivalents - no problem. Been over 2 years now on all of the above.

[Mark Lloyd]

I have used resistors in similar situations, to prevent LEDs from glowing or flashing when they're supposed to be off. You might have to try several to find out what works.

[gfretwell]

It will depend on the residual load from the switching device but in the case of a neon that is typically >120 microamps

[Dean Hoffman]

There's a picture of one here. I hope that it would bleed off any stray current.

[Dean Hoffman]

I hope it would bleed off any stray current. That's what they do on irrigation systems.

[gfretwell]

That is an RC network, intended to mitigate short spikes from the sprinkler valve coil current collapsing. It is a 470ohm resistor in series with a 200V, 0.47uF capacitor. It might bleed off a few milliamps but that is not what it is made to do. If you are experimenting I would start with a 100k resistor, if no joy, use 2 in parallel.

[trader_4]

You've verified this? All the surge suppressors that I'm familiar with for common AC voltages use MOVs, which AFAIK, below the surge voltage, ie when operating normally, have a resistance in the meg ohms, which would seem to rule out it from solving the problem. The impedance of the LED is orders of magnitude less.

[Ralph Mowery]

Right, the MOV will be almost like an open circuit below the activation voltage. After the activation voltage is reached, it acts almost like a short circuit.

My Fluke 87 meter has a maximum range of 40 meg ohms. Severl MOVS I have show up as an open circuit on the meter. Hooking up a test circuit it looks like they pass about 10 or less micro amps of AC when used on

120 volts.

[Ralph Mowery]

Quick bit of research shows that device is rated for DC. Most likely across the contacts of a relay or switch. It would only see current for a very short period of time if used across the contacts of a relay switching DC.

I would not put it across an AC line.