LED's flickering

[ten0rman]

Mods, if this is the wrong forum, please move.

We have a room which by any standards is dark at the best of times. This is due to the previous owners adding a kitchen extension which reduced the natural light available.

When we bought the house there was a striplight, rapidly changed for a three-way fitting using incandescents - this was before all the concern about incandescents wasting electricity. Eventually we changed to CFC's. I bought a pack of 8, and discovered just how crap this particular lot were! I did wonder if it was something to do with orientation as all other CFC's were hanging down, whilst these particular three were pointing up, so I inverted all three lampholders. Not much difference in life, but much increased light as they were now lower. Plus we noticed that sometimes there was a faint glow in one of the three even when switched off.

Incidently, we have a Philips CFC in the hall which is now 20 years old and performing satisfactorily, whilst other CFC's are Osram and again are generally OK. Back to the problem.

Last September, after yet another problem, we decided to upgrade to 15W Warm White LED's at £15 each. Lovely and bright, just what we wanted - except that about 2 months ago one started flickering occasionally. I managed to see which one it was, and transferred it to another room, this one being on a separate feed as well. It continued flickering so it got changed under warranty. Now the flickering has started again. So far I don't know which one as I haven't been looking at it when it flickers. But it's making me wonder just what is going on.

Now, we have a 5-way fitting in our lounge, about 40+ years old, and I do remember some years ago having to completely rewire it because the insulation adjacent to the lampholders was brittle and causing short-circuits. So the thought occurs, could something like this be happening with the LED's, although we have not, as yet, had any fuse failures. Failing that, is it just bad luck, or is there some sort of known failure mode of these lamps? Could it be that the bayonet fittings are duff due to old age?

Thoughts please.

ten0rman

[bungeejumper]

Any dimmer switches in the circuit? They tell me that some LEDs don't like some dimmers (although personally I've had no probs with them.)

I suppose it could be a duff set of bulbs. I did have a bayonet LED bulb in which the two 'tails' that made the contacts with the bulbholder weren't sufficiently proud, so that nothing worked. B&Q own brand, as I recall.

Stupid question, perhaps, but does the flickering coincide with anything else happening in the house? Fridge coming on, boiler firing up?

BJ

[ten0rman]

BJ,
No dimmer switches anywhere. No boiler - on Storage heaters so nothing there. Fridge I suppose is a possibliity - will have to take note.

Not B&Q, rather Bell lighting 18W not 15W as I thought. Sold by our local electrical shop.

I've actually discussed this with the shop concerned and they say that they have not had a bad batch. All they can suggest is to bring all three back and start again. I don't really like that because until proven otherwise, there has to be a nagging suspicion that something here may be causing it. That's why the first one that failed was tried in another socket on a different feed to try and eliminate that possibility. They do have 5 year warranty.

ten0rman

[csearle]

I feel your pain. There are so many different makes and models of LED lamp out there that it is difficult to generalise. As BJ has noted, the inclusion of dimmer switches muddies the waters considerably as not all LED lamps are compatible with dimmers, and some are compatible with only a subset of dimmers (e.g. trailing edge ones).

If there are no dimmers then it could be a poor design of the LED lamps. I failed to understand in your case if the two LED lamps that you experience flickering with were of the same batch and/or flickered in the same room.

One experience I had was a set of nine LED GU10 lamps on a dimmer, where they would flicker unless one of the nine was an incandescent lamp. I had the impression that the dimmer required a minimum load.

I think in your case I would take some time to experiment by putting the offending LED lamp into different light fittings to try to get a handle on whether the problem is more with the lamp or its location. I would not discount the idea of the batch being of a poor design (although at £15 each one would hope this not to be the case).

Regards,
Chris

[ten0rman]

Chris,
Your post & my amended post crossed. Please have another look at my second post immediately above yours.

I've changed one (and I know which one it was). I won't know which other one is flickering until I can catch it in action. Only then will I be able to tell if both are originals, or if the replacement is duff.

tene0rman

[Itsallaguess]

I think in your case I would take some time to experiment by putting the offending LED lamp into different light fittings to try to get a handle on whether the problem is more with the lamp or its location.

I would not discount the idea of the batch being of a poor design (although at £15 each one would hope this not to be the case).

If the lighting circuit itself is suspect, then it might also be worth the OP getting one of these and putting a 240v plug on it with suitably graded flex -



http://www.wilko.com/electrical-accesso ... vt/5330678

Any flickering lamps can then be tested on the completely separate 240v socket circuit, which might help to discount the lighting circuit from the equation if they still flicker on a separate mains circuit.

Cheers,

Itsallaguess

[ten0rman]

itsallaguess,

The fitting in question, and hence the first light that failed is in our dining room. When I found out which lamp it was, I moved it into one of the bedrooms which is on a separate live feed. I'm reasonably certain that the neutrals are separated right back to the consumer unit. There is no earth in the bedrooms (all plastic fittings), but there is in the dining room (metal fitting, plastic switch). I might even have a suitable lamp holder already, certainly I've got plugs & various bits of flex.

Actually, an even better idea - use an existing reading lamp which plugs into the ring main.

Thanks for the idea.

tenorman

[csearle]

Just to speculate a bit here, I'd be highly surprised if the circuits made any difference. In the absence of dimmers it is, IMO, most likely the lamps themselves. C.

[Itsallaguess]

Just to speculate a bit here, I'd be highly surprised if the circuits made any difference. In the absence of dimmers it is, IMO, most likely the lamps themselves.

I'd most probably agree Chris, but where it's possible to quickly and cheaply discount something like this so easily, I still think it's a worthwhile exercise to do so.

I've been down too many rabbit-holes myself where I've kicked myself later on for not checking the simple things first...

Cheers,

Itsallaguess

[tjh290633]

I have a lamp which is a 3-bulb chandelier on our landing. I changed to LEDs and find that there is only one setting of the 2-way switches which works. On the other it flashes. I haven't investigated, but assume that one of the paths has a problem. I might get my friendly local electrician to look at it.

TJH

[csearle]

...but where it's possible to quickly and cheaply discount something like this so easily, I still think it's a worthwhile exercise to do so...

Totally agree. Do all the quick and easy checks first. C.

[csearle]

I have a lamp which is a 3-bulb chandelier on our landing. I changed to LEDs and find that there is only one setting of the 2-way switches which works. On the other it flashes. I haven't investigated, but assume that one of the paths has a problem. I might get my friendly local electrician to look at it.

Er, have you a dimmer as one of the switches Terry? C.

[tjh290633]

I have a lamp which is a 3-bulb chandelier on our landing. I changed to LEDs and find that there is only one setting of the 2-way switches which works. On the other it flashes. I haven't investigated, but assume that one of the paths has a problem. I might get my friendly local electrician to look at it.

Er, have you a dimmer as one of the switches Terry? C.

No Chris, just simple 2-way switches.

TJH

[csearle]

I have a lamp which is a 3-bulb chandelier on our landing. I changed to LEDs and find that there is only one setting of the 2-way switches which works. On the other it flashes. I haven't investigated, but assume that one of the paths has a problem. I might get my friendly local electrician to look at it.

Er, have you a dimmer as one of the switches Terry? C.

No Chris, just simple 2-way switches.

Well this reminds me of an issue that sometimes happens with 2-way switching up & down stairs with low energy compact fluorescents. The function is usually implemented with three-core and Earth cable. The lamp is typically connected to one of the conductors and the supply to another. When the switching is "off" a voltage can be induced from the live to the high-impedance input of the lamp. Eventually the voltage builds up enough to illuminate the lamp but, because there is no real power source behind it, the voltage collapses and the cycle repeats. This can manifest itself in a flashing of the lamp.

It is conceivable that there might be a difference in behavior between the two 2-way combinations because of the proximity of the "strappers" (as they are called) within the three core cable.

I think the solution would be to slightly increase the load. A high-ish value resistor in parallel with the lamp would probably do it (although no normal electrician would suggest this).

Chris

[Devjon]

Good idea Chris, perhaps replacing one of the LED lamps for an incandescent or high wattage compact fluorescent lamp would prove if this is the case.

( I have a strange issue, there are 6 down lighters in the kitchen these are fed by individual transformers, as for some inexplicable reason I used MR16 instead of GU10 when they were installed. I changed from halogen to MR16 led and all worked well. After a couple of years I replaced the existing LED lamps which were the ones with multiple individual chips to newer single chip versions. One of the replacement lamps was constantly flickering, I tried several of the new lamps but the problem persisted, if I put the one of the original replacement multi chip lamps in the fitting the problem disappeared )

Reading back what I have just written I can see that the issue is probably with that one particular transformer feeding the fitting.

[bungeejumper]

( I have a strange issue, there are 6 down lighters in the kitchen these are fed by individual transformers, as for some inexplicable reason I used MR16 instead of GU10 when they were installed. I changed from halogen to MR16 led and all worked well. After a couple of years I replaced the existing LED lamps which were the ones with multiple individual chips to newer single chip versions....

Reading back what I have just written I can see that the issue is probably with that one particular transformer feeding the fitting.

Maybe I'm misunderstanding something, but if you're on LEDs, why do you need to have transformers at all? When I swapped my old low voltage halogen downlighters for LEDs, I just fitted 230V LEDs and scrapped the transformers entirely.

A quick Google confirms that 12 volt LED downlighters are available (https://www.ledhut.co.uk/3-3-watt-mr16- ... ement.html?), but what's the advantage? (Apart from in caravans, of course?) Just curious.

BJ

[Slarti]

Just to speculate a bit here, I'd be highly surprised if the circuits made any difference. In the absence of dimmers it is, IMO, most likely the lamps themselves. C.

In our living room we have 3 wall fittings on one switch, which are the 3 lights that are on the most and one of them is an LED killer.
The LED lamps in the other 2 fittings have been there since early 2014, but 3 LED lamps in the 3rd fitting started flickering within a few weeks.
1 effectively died and was changed by LED Hut, the other 2 are giving service in other fittings, where a bit of a flicker doesn't matter as they are used so infrequently and for such a short time.

An incandescent in the odd fitting seems to be working fine.

Those lamps were 40W candle replacements, but last week I returned home, only to be told that the 60W replacement in the downstairs loo had started flickering after only being in place since August. I'll have to test it elsewhere and see how it is then.

I think that there can be sensitive fittings, but that also some of the LEDs aren't built as well as they should be.

Slarti

[csearle]

I think that there can be sensitive fittings, but that also some of the LEDs aren't built as well as they should be.

A good point. Especially the heat management of various fittings. Clearly LEDs usually disspiate much less heat than incandescent lamps, especially halogen ones, but it will not be zero so unless the design allows for the heat to escape adequately then the temperature will probably rise. I can imagine that the LED driver within the lamp is more sensitive to overheating than the simple connections of an incandescent lamp. C.

[Devjon]

Maybe I'm misunderstanding something, but if you're on LEDs, why do you need to have transformers at all? When I swapped my old low voltage halogen downlighters for LEDs, I just fitted 230V LEDs and scrapped the transformers entirely.

A quick Google confirms that 12 volt LED downlighters are available (https://www.ledhut.co.uk/3-3-watt-mr16- ... ement.html?), but what's the advantage? (Apart from in caravans, of course?) Just curious.

BJ

Well BJ, long story short. It was a new ceiling in pre LED days and the boss of the Electrical wholesalers that the company I worked for spent a lot of money with each year let me have the Halogen fittings and transformers at a truly excellent price

I was going to replace the MR16 with GU10 as you suggested, and took one of the down-lighters out of it's hole in the ceiling to investigate. There's not enough slack in the mains cables to the transformers to reach the fittings and as I can only get one hand through the hole where the fitting sits there's no room to work so I'm stymied.

[ten0rman]

As the OP...

I've now narrowed it down to one of the three lamps, and it's one of the two remaining originals. So it's beginning to look like a bad batch.

Looking at all the suggestions, this is indeed a two-way circuit. I'm assuming that as the cables have been in since the house was built (1966) and as there is no earth to any of the switches or lampholders other than what I have installed in order to use metallic fittings, then I suspect that there will be no earth wire in the cables.

The first lamp to fail was moved into a bedroom (strangely the only one with a two-way circuit) which is on a separate fuse to the unit in question, but the idea of testing on the ring main (using a reading lamp) is what I shall try next thus eliminating any strange effects caused by two-way switching.

Not noticed anything with the fridge yet.

Just one other silly thing. I look to have omitted to say that the lamps in question are flickering off when they should be on. They always start up, but then after a short while flicker off. I have had the situation where a CFC, in the same fitting would you believe, used to glow faintly when it was supposed to be off.

Regards,

ten0rman