Any electrical experts? LED bulbs not going out completely
Any electrical experts? LED bulbs not going out completely
Author
Discussion

Alice Cupra

Original Poster:

1,034 posts

267 months

Saturday 25th October 2008
quotequote all
I have a light fitting in the house which is a fairly standard 4X GU10 spotlight fitting, basically the 4 bulbs on a metal "bow" shaped fitting.

I decided to swap the standard GU10s for four LED ones.

On fitting them, I have noticed that the LED bulbs do not go out completely when I switch them off, but remain on very dimly.

Oddly, if I replace ONE of the bulbs with a standard GU10, then the LED ones go out completely.

What could be causing the problem?

Do I have a dodgy earth on the fitting, or is it just a "feature" of the LED GU10s?

Cheers.

GTIR

24,741 posts

296 months

Saturday 25th October 2008
quotequote all
Do you have a transformer for the original lights as it may be that thats powering them?


ETA I am NOT an expert!

Edited by GTIR on Saturday 25th October 18:41

Pigeon

18,535 posts

276 months

Saturday 25th October 2008
quotequote all
Leakage... probably capacitive leakage between the wires in the cable to the switch... when you put an ordinary bulb in it shorts it out.

yourang youtang

176 posts

216 months

Saturday 25th October 2008
quotequote all
Alice Cupra said:
Do I have a dodgy earth on the fitting, or is it just a \"feature\" of the LED GU10s?
It\'s not that.

You\'ve got a current running through there - check your switch/dimmer.

Alice Cupra

Original Poster:

1,034 posts

267 months

Saturday 25th October 2008
quotequote all
yourang youtang said:
It\'s not that.

You\'ve got a current running through there - check your switch/dimmer.
Cheers.

I think I have a few new switches lurking in the garage.

I'll swap it for a new one and see what happens......

GreenV8S

31,021 posts

314 months

Saturday 25th October 2008
quotequote all
Pigeon said:
Leakage...
^^^ What he said.

An ordinary incandescent bulb will happily soak up a trickle of current without getting hot enough to glow. An LED works differently and will glow with any amount of current - it just gets dimmer and dimmer as the current goes down.

If it's any consolation, the only difference with the LEDs is that you can see the leakage - it's still there with the incandescent bulbs.

Adrian W

15,532 posts

258 months

Saturday 25th October 2008
quotequote all
Probably caused by some inductance induced in the cheap power supply for the LED's, is all of the three plate wiring still above the light? if so you need to move the live's further away.

Alice Cupra

Original Poster:

1,034 posts

267 months

Sunday 26th October 2008
quotequote all
Cheers for all the replies so far, guys.

I have just swapped the light switch for a brand new one I had lurking, just to rule out a dodgy switch.

They are still glowing away to themselves, so that rules out the switch.

I am going to leave them in for the time being, to see if they go out completely over the next few hours, in case it is just a residual capacitance(?) issue.

If all else fails, I suppose I could just replace one of them with an incandescent bulb to stop them visibly glowing, or learn to live with it.....

Pigeon

18,535 posts

276 months

Sunday 26th October 2008
quotequote all
They'll keep doing it. Capacitive leakage doesn't "fade away" - this is AC, not DC wink

Might be worth checking that the earth conductors in your lighting cables are actually connected to earth. I have seen st installations where someone hasn't been arsed to connect them... and if that was the case here then it would make the problem worse.

Alice Cupra

Original Poster:

1,034 posts

267 months

Sunday 26th October 2008
quotequote all
Pigeon said:
Might be worth checking that the earth conductors in your lighting cables are actually connected to earth.
I certainly noticed that the earth cable in the switch housing is all present, correct and connected.

Will remove the light fitting at some point and check that there's one connected up at that end, too.

Of course, where they go after that is anybody's guess.....

Is there a simple way to check that the earth cables are actually earthed?

Many thanks.

Pigeon

18,535 posts

276 months

Sunday 26th October 2008
quotequote all
Simplest way to carry out a half decent test without "specialist equipment" is with a car battery and a headlamp bulb (and some long bits of wire)... use the battery and bulb to check continuity between the earth wire behind the switch and an incoming metal water pipe.

gordon lonsdale

109 posts

222 months

Sunday 26th October 2008
quotequote all
I've got six of these 50w gu 10sin the main bedroom ,fitted from new and each adding massively to the heat loss from the room because of the gap around the sides and also possibly allowing a back draught bringing with it glass fibre dust from the loft.They do give a fantastic light but at what a cost , the fire resistance of the cieling must also be compromised because of this air gap. Of course on the plus side when theyre switched on there is no need for lights in the loft its lit up like a fairground.

gordon lonsdale

109 posts

222 months

Sunday 26th October 2008
quotequote all
I've got six of these 50w gu 10sin the main bedroom ,fitted from new and each adding massively to the heat loss from the room because of the gap around the sides and also possibly allowing a back draught bringing with it glass fibre dust from the loft.They do give a fantastic light but at what a cost , the fire resistance of the cieling must also be compromised because of this air gap. Of course on the plus side when theyre switched on there is no need for lights in the loft its lit up like a fairground.

mybrainhurts

90,809 posts

285 months

Sunday 26th October 2008
quotequote all
You be 'arve got a ghostie there...

Pigeon

18,535 posts

276 months

Sunday 26th October 2008
quotequote all
'E be 'arve replying in the wrong thread, we be talkin' about LEDs here...

mybrainhurts

90,809 posts

285 months

Sunday 26th October 2008
quotequote all
Arr, oi' knows thart....


Raverbaby

896 posts

216 months

Sunday 26th October 2008
quotequote all
It happens when there is capacitive coupling which builds up where two wires lie close together. This happens most often with 2-way switching because you have a live cable running quite a long way between the switches, and voltage "leaks" from the live wire to the switch, into the "dead" wire, in the same cable, that goes to the lamp.

because of the electronic circuitry in the energy-saving lamp, it can store it up until it has enough for a momentary flicker.
this not caused by faulty insulation, it is to do with the faint mangnetism which is caused when electricity flows through a wire.

shameslessy copied and pasted whistle

Goochie

5,799 posts

249 months

Sunday 26th October 2008
quotequote all
gordon lonsdale said:
I've got six of these 50w gu 10sin the main bedroom ,fitted from new and each adding massively to the heat loss from the room because of the gap around the sides and also possibly allowing a back draught bringing with it glass fibre dust from the loft.They do give a fantastic light but at what a cost , the fire resistance of the cieling must also be compromised because of this air gap. Of course on the plus side when theyre switched on there is no need for lights in the loft its lit up like a fairground.
If the fittings you have are not fire rated, there will, of course be a reduction in the fire performance of the ceiling. Part B of the building regulations states that all openings in a fire compartment (the room) for wiring, and lighting etc. should be provided with adequate fire protection.

It is common practice to fit a fire rated "Flameguard" type downlight in such a ceiling.



Fitting one of these will dramatically reduce the draft you have at the moment too.

Alternativly, fit a loft insulation support box over your existing fittings then insulate over the top of that. Dont insulate directly over any downlight unless it uses a low energy florescent or LED lamp.

You can either buy a ready made sheet metal box or fabricate a show box sized enclosure from plasterboard.



Edited by Goochie on Sunday 26th October 22:41

Deva Link

26,934 posts

275 months

Sunday 26th October 2008
quotequote all
gordon lonsdale said:
the fire resistance of the cieling must also be compromised because of this air gap.
If it troubles you, there are fire hoods listed at Screwfix:
http://www.screwfix.com/cats/A454568/Lighting/Inte...

Alice Cupra

Original Poster:

1,034 posts

267 months

Monday 27th October 2008
quotequote all
Raverbaby said:
It happens when there is capacitive coupling which builds up where two wires lie close together. This happens most often with 2-way switching because you have a live cable running quite a long way between the switches, and voltage "leaks" from the live wire to the switch, into the "dead" wire, in the same cable, that goes to the lamp.

because of the electronic circuitry in the energy-saving lamp, it can store it up until it has enough for a momentary flicker.
this not caused by faulty insulation, it is to do with the faint mangnetism which is caused when electricity flows through a wire.

shameslessy copied and pasted whistle
I think this is what could be happening on mine.

The light is on a 2 way switch (top of stairs and bottom of stairs). Additionally, both of these switches are double switches, and the light on the 'other' switches of each are also 2 way lights.

Nightmare!

Can I be cheeky and ask where you "shamelessly copied and pasted" from??? hehe