LED lights misbehaving when off

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Disrespective

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#198928 28-Jul-2016 13:54

I've been thinking about why this happens for a while, but i'm not sure if i'm right...

If I use a basic LED bulb in any socket in the house, it will flash on and off continuously when the circuit is off, but work fine when on.

Our house was built in 1970 and has the original wiring and I've been trying to convert the masses of incandescent lights to LED's, but have hit this small hiccup.

I originally started with a handful of Limitless LED's and that was going fine until they started dying, in quick succession. I'd had them a while, so figure they're just failing due to age (Even though it's less than the estimated rated lifetime). So I picked up a few Lifx bulbs and again, all fine but i'm now wary of our wiring and them dying prematurely if it's a problem with the wiring.

My theory is that there is some sort of residual current in the circuit which an incandescent bulb isn't susceptible to due to the extra resistance across its filament.

As i'm writing this i'm wondering if I put an incandescent bulb back into one of the sockets on the same circuit and turn it on, if that will smooth out the circuit to let the LED bulbs work fine. I don't really like this idea though as it sort of defeats the purpose of having LED's (power savings).

There are two lighting circuits, one for the back half (beds and bath etc) and one for the front (lounge, dining, kit) so any fix would have to be done twice.

Anyone come across something similar or have a fix I can implement? I don't want to have the expense of buying a house lot of Lifx, nor do I want to have to use incandescent bulbs.

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#1600181 28-Jul-2016 14:12

Use a multimeter to see if any AC voltage is present at the socket when the circuit is tuned off?

Beyond that I would be getting sparky in to look at it.

Mike

hsvhel

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#1600186 28-Jul-2016 14:22

You need to have that checked by an electrician

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ubergeeknz

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Vocus

#1600187 28-Jul-2016 14:23

Yes could be some kind of current leakage, possibly dangerous, you'll want to get that checked by an electrician IMO. Off is supposed to be "off".

wellygary

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#1600201 28-Jul-2016 14:47

ubergeeknz:

Yes could be some kind of current leakage, possibly dangerous, you'll want to get that checked by an electrician IMO. Off is supposed to be "off".

No, its not leakage, and yes the circuit is off,

What is likely happening is at the switch the 240V live side of the switch is causing an inductive current on the light side of the switch,

The LED has a nice capacitor in it that slowly charges from this low current and then flashes into life,

From memory 70s style switches have great big chunks of copper in the switch, which would be great for creating an inductive charge across the circuit,

There is no one solution, you could change a switch to a more modern one, or try a differnt brand of bulb,

But even having a live wire running next to you light feed could also induce enough current for them to flash, so it might not be an easy fix

ubergeeknz

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Vocus

#1600211 28-Jul-2016 15:09

Oooh induction :) I had not even considered that would produce enough current to do this. Cool!

wellygary

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#1600213 28-Jul-2016 15:17

ubergeeknz:

Oooh induction :) I had not even considered that would produce enough current to do this. Cool!

It only becomes a problem because LEDs have capacitors, and the miniscule levels of current just keep filling it up...

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#1600243 28-Jul-2016 15:50

Yep, have exactly the same issue.

The input impedance to these things is quite high, and in most houses there is enough induced voltage (capacitive coupling) in the wires

to allow the switch mode to charge up and when it reaches "on" voltage for the LED, it flashes, discharging the circuit.

This only happens in our house (6 years old) where there in only one lamp in the circuit.

We just use CFLs in those 2 lamps.

sir1963

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#1600245 28-Jul-2016 15:56

wellygary:

ubergeeknz:

Yes could be some kind of current leakage, possibly dangerous, you'll want to get that checked by an electrician IMO. Off is supposed to be "off".

No, its not leakage, and yes the circuit is off,

What is likely happening is at the switch the 240V live side of the switch is causing an inductive current on the light side of the switch,

The LED has a nice capacitor in it that slowly charges from this low current and then flashes into life,

From memory 70s style switches have great big chunks of copper in the switch, which would be great for creating an inductive charge across the circuit,

There is no one solution, you could change a switch to a more modern one, or try a differnt brand of bulb,

But even having a live wire running next to you light feed could also induce enough current for them to flash, so it might not be an easy fix

Its not the switch, we have a 6 year old house with PDL600 series switch though out and have the same problem, but ONLY on the 2 circuits that only have one lamp.

A CFL lamp will not exhibit this issue.

It will be from the capacitive coupling between wires. Only need a bit over 0.6v between phase and neutral and it will start charging the cap up in the lamp, and when it gets to a certain charge the lamp turns on, discharging the cap and we start all over again.

frankv

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#1600277 28-Jul-2016 16:12

I ran into something like that a few years. Can't remember why now, but in an older house I measured 80V AC across a light socket that was turned off.

I consulted an electrician, and he said not to worry... it was induced, and there wouldn't be enough current to do any harm.

This is at the ragged edge of my knowledge envelope (hoping someone electronically knowledgeable will step in here), but I'm wondering if you put a small resistor in series with your capacitor, that would reduce the current when the switch was off and lower the flash rate. Or maybe a large resistor in parallel to the capacitor, to dissipate the charge?

Disrespective

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#1600283 28-Jul-2016 16:22

Yeah, i'm running all new Schneider switches (saturn zen push button switches are nice) so it's unlikely to be them.

That being said, I haven't changed all of the switches over and have some load correction devices in the cupboard as the circuits we were hoping to dim will only have a few bulbs on at most. I wonder if the load correction devices can be used on vanilla circuits to eliminate the flashing. I'll have to have a tinker.

I considered an induced current, there's a total of 16 circuits in my 87m2 house... it's ridiculous the amount of wiring there is, so figured it'd be from there.

mdf

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#1600323 28-Jul-2016 19:26

Disrespective:

Yeah, i'm running all new Schneider switches (saturn zen push button switches are nice) so it's unlikely to be them.

Ooh, those are nice! If you don't mind me asking, how much approx do they run a switch? Are you using the smart/CBUS ones or the normal ones?

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#1600378 28-Jul-2016 22:31

It's worse on wiring where there are multiple switches so you have really long switch wires. LEDs without a power supply will just glow dimly from the leakage. I'm my lounge with about 40m of switch wire between the lights I can actually read by the light from some candle shaped led lamps glowing when off.

Solution is a capacitor across the lamps to give a low impedance path for the leakage when off and it's a capacitor so no real power used when it's on.

The ones we used were some clips thing made for dimmers if I recall right.

Richard rich.ms

Disrespective

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#1600507 29-Jul-2016 08:30

mdf:

Disrespective:

Yeah, i'm running all new Schneider switches (saturn zen push button switches are nice) so it's unlikely to be them.

Ooh, those are nice! If you don't mind me asking, how much approx do they run a switch? Are you using the smart/CBUS ones or the normal ones?

Fortunately for me I have a connection which can get me very very good rates on the Schneider gear. Normal trade price on a 3-gang Z4025 switch is about $62 so not cheap. But then again, trade price on a 3 gang R5043NL c-bus switch is ~$225, so I was quite happy to forego those.

pbgben

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#1600526 29-Jul-2016 09:01

Perhaps one of those magic power saving devices will help? Its just a resistor and a capacitor in a sealed box that's meant to combat phase shift. (I know they are a snake oil product, but this case my be one of the few it can help with)

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#1601454 30-Jul-2016 21:16

Be cheaper to just get a capacitor from Jaycar most likely. And I would doubt that someone making snake oil devices would ensure that the components they use have the relevant approvals for connection directly to mains.

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