LED Light Bulbs

Not Directly ME related.

Today I changed five of the bayonet fitting light bulbs in the house. One of the ones I replaced is in the hall. The light switches on and off from the switch perfectly normally, but when the light is switched off it flashes about once every 20 seconds???? I tried a second LED bulb in the same holder and it does the same thing. The bulb I took out (and have since put back in !) is a low energy CFL type.

Any Ideas?

Martin C

When i swapped out our living room ceiling lamps from low energy to led I found they remained glowing fantly when switched off. I gave up figuring it out after soem hours. If I recall correctly local sparks spent a while fiddling in the ceiling rose having discovered 120v across the bulbs when off...

Are the lights on a dimmer controller ? I had to replace my dimmers to low load versions as the load presented by the LED bulbs was so much less than normal bulbs that the controller would not stabilise and did some weird things.

We have just had a kitchen extension fitted and 2 way LED lights were fitted (two indipendent banks of 4 lights). We had the same issue that the lights would glow dimmly when switched off. (one circuit only) To cure this I fitted a mains neon across the last light in the chain, this glows but is in the celing void so not seen and the LED light switch on and off normally. The two way switching cable (4 core) is acting as a transformer and inducing 80 Volts between adjacent cores of the cable caulsing the LED lights to glow dimmly without the neon.

Hi

I had this in the hallway landing light upstairs when you have two way switching. I believe the problem is caused by capacitance of the long cable running to the downstairs switch. The cable is so long that the capacitance of the between the live and switch line is enough to cause the light bulb to strike and then decay and hence the flashing. Sometimes the bulb would seem to glow.

regards

Steve

I think the problem is caused by the capacity coupling between the live feed and the switch wire. Being in a hall I suspect that it connected to a two way switch system so there will be quite a long length of cable where the switch wire and live feed are in the same cable so the capacity will be greater. I have not seen an LED lamp flashing when switched of but I have had problems with them glowing dimly. I have solved the problem by connecting a capacitor in parallel with the lamp. (The capacitor must be rated for connection across the mains. X or Y rated but I can't remember which.) To get a suitably packaged capacitor I have used a contact supressor. (Which is a capacitor with a series resistance.) such as this one. They are terminated with flexable insulated leads so that can be fitted in the ceiling rose or light fitting. This works by forming a capacitave potential divider with the cable capacitance as one part and the added capacitor as the other. This reduces the voltage across the LED when the switch is in the off position so it is too low for the LED to light. A resistor could be used but it would gnerate heat when the light was switched on. There will be no heat with a capacitor as the current is out of phase with the voltage. The resitor in the contact supressor will generate a very small amount of heat but it is not enough to cause a problem. A contact supressor with the lowest value series resistor is the best to choose.

Les.

I had a similar-ish problem with my LED lamps used in conjunction with dimmers. At minimum setting, the lights were still lit / flickering. As the fittings were 5-8 bulb chandeliers, I put an incandescent lamp in one of the positions to load it down. This worked well - until eventually said filament bulb failed (as they do eventually), at which point the dimmers popped. Not impressive. Out of 4 dimmers I am down to the last one. Along with 4 out of 7 remote controls dead on arrival, these Varilight dimmers (UK made, available from Screwfix / B&Q) were a complete waste of money. If this is the best we can make in the UK these days, we should try our hand at something else. Anything else.

Rant over, I did note that the installation leaflet mentioned an optional accessory that contains a resistor to achieve the same effect (loading the dimmer without popping it, ideally). Naturally, I have not actually seen one for sale but it's now academic for obvious reasons. I'd look for something similar.

Murray

Glowing dimly tube heater element in older style fluroescents was usually caused by the switch being connected into the neutral and not line conductor. The incorrect polarity at the switch would be discovered when testing the circuit.

Emgee

Edited By Frances IoM on 08/01/2017 17:02:08

Edited By Frances IoM on 08/01/2017 17:03:07

The problem I have with LED lights, especially the rectangular floodlights, is radio interference caused by them. It comes {I guess} from the oscillator gubbins which drops the 230v to LED voltage, and I wonder if the floodlights, being designed for industry rather than home use, are not designed with shed radios in mind. I will eventually find a solution, but if anyone knows of a quick or easy answer, do let on.

PS I also get buzzes on the radio from my Jaguar inverter, but not so loud.

Cheers, Tim

I have four B22 LED wall light fittings plus a 20w LED outdoor floodlight, all seem to work normally.

Out of interest I have noticed some LED replacement bulbs state "not suitable for use with dimmer switches" while others say "suitable for use with dimmer switches" well worth watching out for this one as they seem to be of very similar physical appearance.

Edited for spelling.

Edited By V8Eng on 08/01/2017 17:49:43

We had similar issues with the older fluorescent types (with a spiral or folded tube). Eventually we found that some makes flashed briefly every 20 or 30 seconds when off, but a different make appeared to be OK. What was confusing was that it was not consistent. A bulb would flash in one socket, but in a different room, it worked OK. There was no pattern to this - bulbs which worked in one place would flash in another. We eventually got everything to work by 'selecting' bulbs in different rooms. The house is only about 4 years old, and I am sure all the wiring is OK.

Just recently we changed over to LED bulbs instead to reduce our consumption even further, and they all worked OK, regardless of where they were fitted. We did notice that they appear to have a 'soft' switch-off. They grow progressively dimmer, quickly going almost off, but a slight glow is visible in a darkened room for maybe 10 or 15 minutes - this suggests a large internal capacitance to me.

Out of curiosity, I measured the voltage across each socket when they were switched off, because despite the new wiring, I suspected maybe a high resistance circuit when the switch was off, but the switches do appear to be 'open-circuit'. The first meter I used was a high-impedance electronic type, set of course to AC volts. I noticed when the switch was off it appeared to indicate a random low voltage, maybe 2 or 3 volts, which was constantly changing. I put this down to 'noise pickup' aggravated by the high impedance meter - I later tried an old low impedance moving coil type, and got no readings. Don't really know what this proves, especially since we had trouble with the fluorescent type, rather than LEDs.

(Edit) Incidentally, changing connections L/N at the socket had no effect on the flashing bulbs

Edited By An Other on 08/01/2017 18:41:59

Interesting!

I just fitted two very cheap LED bulbs, a candle and a standard one from Toolstation, both in two packs for under £3 so I have two spares. They seem to be very good. Nice to fit a candle shape to replace a CFL in a 'candle holder' Now I know it works I will stock up on enough (8 more) to replace all the CFLs as they go.

Neil

I find that some LED lamps come brighter after a couple of minutes. I also have two more which glow for a few seconds when switching off presumably a capacitor discharging somewhere

Roy

Edited By roy entwistle on 08/01/2017 20:08:32

Thanks for all of the replies. A bit more information :-

The bulbs being used are Screwfix ones (made by Lap). I'm not using them with a dimmer switch but they are connected to a two way circuit (but its quite a short one, the switches are only about 10' of cable apart). The earth conductors are all connected (where possible) but there will be no earth connections at the bulb end - the earth is terminated at the rose.

I have used the same bulbs in the other part of my hall, it uses two bulbs and a longer two way switching circuit but it does not display the same flashing effect. Very strange.

Martin C

The "electronic transformer" supplying the 5x 20w 12v tungsten spots in my utility/workroom died after many years of service. Taking this as an opportunity to change to LED I purchased 5x 5w LED spots of the LAP brand and a LED driver (30w 12v constant voltage). After wiring up I switched on and all the spots flashed in unison. Carried out fault finding by process of elimination and found that connecting any 3 spots in any position worked. With the 3 spots switched on I connected the other 2 and all 5 worked OK. Switched off and on and flashing started again. Removed any 2 and all OK. Thinking that the total load of 25W was maybe too close to the 30w limit I bought and fitted a 50w driver. Exactly the same happened!

Any advice would be greatly appreciated.

Gordon.

In the spirit of this subject heading, CPC Farnell have emailed an offer on multi packs of LED lamps.

**LINK**

I have no connection with them except as a satisfied customer.

Edited By V8Eng on 09/01/2017 18:55:05