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HELP! Replacing 10w G4 bulbs with 12v LEDs - LEDs flash once and turn off

Discussion in 'Electrics UK' started by Chamsters, 11 Jan 2021.

  1. Chamsters

    Chamsters

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    Hi all,

    Was really hoping for some help on an issue I'm having.

    Have been doing a mini project replacing 9 10w 12v G4 bulbs with softer 12v 3w LEDs. I was doing them one at a time to make sure there were no issues and I could test each individual light.

    I got through 7 without any issues whatsoever. The LEDs would fire up without any problem.

    But with light 8, when I switched on the light, all the lights flicked on, then went off and stayed off. When they're off, if I check for live current on each of the lights I'm getting an alert - so there is power flowing, but the lights aren't switching on.

    To try to troubleshoot I removed each of the lights one by one until I basically had 1 left - the first I had installed. Same issue.

    I'm now left with the entire set of 9 not working...

    Any tips / suggestions / troubleshooting recommendations?

    Thanks!
     
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  3. AndyPRK

    AndyPRK

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    It needs 1 filliament bulb left in to load the transformer.

    On big lights I leave 2 in
     
  4. 333rocky333

    333rocky333

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    Do you have access to the Transformer to take a photo of the label
     
  5. ericmark

    ericmark

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    As said the standard electronic transformer is often rated 20 - 100 VA or similar, VA is as far as you need to know the same as watts. Once the load goes below the minimum the unit tends to switch off. There are a few ways around the problem, the newer electronic transformers tend today to go down to zero, but some LED lamps stipulate 50 Hz and to get 50 Hz you need a toroidal transformer not an electronic transformer, some times we move to DC using a driver but a driver in theory should be current limiting, and you want voltage limited, so need to carefully read the label.

    But the easy method is leave one or two quartz bulbs in place.
     
  6. Buy proper LED lights to replace the old system. As with so many things dont try to convert something old to a fundamentally new system by partially swapping in new bits.
     
  7. ericmark

    ericmark

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    There are some bulbs which are not preferred with LED, however in the main far better with a bulb and fitting system, in fact the EU was in the process of banning the lamps with non replaceable parts.

    The big problem at the moment is to select bulbs which do not rapid flash, some bulbs have an electrolytic capacitor across the LED's to reduce the 100 Hz flashing.

    But only way is to try them, if you get a head ache, change make of bulb, there is clearly a problem when you need to change whole lamp.
     
  8. bernardgreen

    bernardgreen

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    and some intentionally pulse the LED element(s) to make the lamp appear to be brighter.
     
  9. ericmark

    ericmark

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    Since many of the 12 volt can work on DC, unless using switch mode regulation one would hope with DC supply no pulsing. With the 230 volt versions, often a capacitor is used to control current, so will not work with DC, in fact need 50 Hz AC, however the marking on bulbs are confusing to say the least, just selected a random bulb out of the draw, it does say if you look carefully AC 220-240, 50 Hz 470 lm 200° beam angle 5.5 watt. But in large writing it says 40W, it is not 40 watt, at 470 lm it would replace a 7 - 10 watt CFL and around 28 watt quartz, bulbs older than that did not publish lumen, The hand-blown, carbon-filament common light bulb switched on 1901 it says now gives out the light one would expect from a 4 watt night light, OK rather old, but the old incandescent bulbs were a compromise between life and brightness, and the old rough service bulbs were always dimmer than the standard household bulb, and even if you measured the standard household bulb, the voltage range 220 - 250 would make a huge difference, so no one can really say what the output was.

    A Tesco 40 watt BA22d pearl bulb 220-240 volt states 360 lumen. Another make still boxed says 350 lumen not 470 lumen, the un-boxed bulbs don't give lumen output. A 10 watt G4 quartz I found at rated 120 lumen, so around 1.4 watt LED is an equivalent, but often the replacement for 10 watt is claimed as 1 watt, but the G4 tungsten lamp was never made in other than quartz so compression has to be to a quartz lamp.

    The net result is we get it wrong, last house living room on buying in 1978 had two 100 watt bulbs, these were not really bright enough so 3 bulb chandelier and either 40 watt or 60 watt bulbs used, with CFL tried 11 watt but looked rotten so changed to 5 bulb chandelier and so 10 x 8 watt globe CFL, to be frank not bright enough, but expensive and did not last long so moved to 3 watt LED candle, these seemed brighter, but when we tried to read, realised not big enough, so moved to 5 watt LED. So 50 watt LED replaced 200 watt tungsten. That's not what the conversion charts say.

    What we did was move bulbs room to room, the 3 watt were moved to dinning room when 5 watt fitted in living room, what is important then is the ability to change bulbs. Once you go to integral LED your stuck, you can't go bigger or smaller, yes I have a draw full of bulbs, where I have stocked up with tungsten, or swapped sizes with CFL and LED, in theory should not need to ever buy another bulb, but I have a wife, no love we don't want G9 bulbs fell on deaf ears, whole house has 6 G9 bulbs, my bulb draw has 15 spare bulbs, and it seems she ordered another 4 as the colour was wrong?
     
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  11. What I meant was if you want low voltage LED lights put in a low voltage LED system rather than put LED bulbs into a system which was designed for halogen.
     
  12. I was looking for bulbs online recently, and one site was selling CFLs and LEDs, quoting different lumens but the same equivalence.

    I was tempted to email and ask if CFL lumens are different to LED ones. But maybe they are? Does the colour of the light make a difference?


    I stocked up on traditional bulbs bigtime. Never used any of them. Going to post a new topic about buying LED replacements.
     
  13. plugwash

    plugwash

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    Trouble is the lighting industry seems to have shown no interest in creating a flexible vendor-neutral system for LED lighting.

    So you either buy LED bulbs designed to go into existing incandescent or halogen fittings or you buy fittings where you are expected to change out the whole fitting when it fails or when you want to change the light output level.
     
  14. ericmark

    ericmark

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    As far as I am aware the GX53 has never had a tungsten option. And of course all fluorescent fittings have never had the option to fit tungsten.

    With extra low voltage lapcraft have made fluorescent fittings for over 40 years, and buses have also used fluorescent fittings well before the 70's.

    However the extra low voltage spot lamp was made so the tungsten filament is thicker so extending bulb life, so the whole point is lost when we move to LED, there may still be a reason for extra low voltage in bathrooms, and motor vehicles, however 12 volt is a problem, as 12 volt in a caravan is more like 13.8 volt, and the lights need to work on DC with a voltage range, often 10 - 30 volt, so they have a built in pulse width modulated controller, and need a DC supply which is not also pulse width modulated or they will not work well together, so selecting a 12 volt driver one does not know if smooth enough to power a bulb which has a pulse width modulated controller built in.

    I find extra low voltage is a pain, even with tungsten a 12 volt MR16 bulb for a caravan was not the same as a 12 volt MR16 for a house, as caravan one was really 13.8 volt not 12 volt. I have used 12 volt lighting and 24 volt lighting in a farm house where only 240 volt was from a generator, but in the home today no real point, very few bathrooms need 12 volt lighting.

    So would when ever possible move away from extra low voltage and fit low voltage instead, so no transformers etc.

    The exception is where the power supply wires are aerial fixings and the lamps simply drop on where required, clearly low voltage would be rather shocking if that method used, it needs to be SELV (separated extra low voltage).
     
    Last edited: 13 Jan 2021
  15. ericmark

    ericmark

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    He is not using a low voltage system, the G4 is extra low voltage, it is the G9 which is low voltage.
     
  16. bernardgreen

    bernardgreen

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    My first employment was at LabCraft in 1964. They had just started producing 12 volt and 24 volt fluorescent lighting. Previously they had manufactured signal strength meters for VHF and UHF aerial installers.

    Enough of nostalgia for the good old days,

    Running LED elements on 12 Volt DC is a very simple and reliable way to produce light, Three white LEDS in series with a current limiting resistor is all that is needed to produce a light source. An un-regulated 12 Volt supply from a battery may be as high a 14.5 volts ( charger active ). The value of the current limiting resistor is chosen such that the current is below the maximum current for the LED elements when the supply is 14.5 Volts. The brightness will vary when the supply voltage changes. The number of light sources (3 LED elements + resistor) should be chosen so as to provide enough light at 12 Volts. If at 14.5 Volts there is too much light then some of the light sources could be turned OFF.

    The optimum ( in my opinion ) is to have a regulated DC supply of 9 Volts feeding the light sources ( 3 LED elements + resistor ). In almost all cases the light is bright enough and the LED elements being under run will have a far longer life time. The 9 Volt supply can be from a simple linear voltage regulator such as a LM317 DATA feed with DC. Some heat may need to be dissipated in the LM317 but this should not be a problem.
     
  17. ericmark

    ericmark

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    I would agree, except that this firm specialises in 12 and 24 volt lighting and with a 10 - 30 volt bulbs which clearly use some switch mode or pulse width modulated control. With caravan or boat we want the 12 volt lighting to be as economic with battery power as possible, looking for 100 lumen per watt, but with houses we accept 75 lumen per watt, which is not as good as the fluorescent fittings using HF ballasts.

    I stage 12 volt battery charger can raise volts to 14.8, the BS 7671:2008 says 14 volt is the limit, but clearly manufacturers of caravans don't take any notice of that as stage chargers still fitted, I am not sure if 3 LED's and a resistor can really take that extra voltage, and the power used with a DC to DC inverter to regulate the voltage is not really worth it when you can get bulbs designed for the variation which also give more lumens per watt.

    But 9 LED bulbs with leads no longer than 300 mm as most manufacturers recommend seems unlikely. So it is likely they have over length extra low voltage cables, which means either a toroidal transformer, or move to low voltage (230 volt), my son replaced the old 65 watt fluorescent fitting (5200 lumen approx) which I had already fitted a LED tube into 24 watt (2200 lumen) with 16 MR16 style down lighters I think 3.5 watt each (275 lumen) so total 56 watt at (4400 lumen) and it seems no brighter than when using half the lumen at 2200, and not as bright as the original 5 foot tube and gone from 91 lumen per watt to 78 lumen per watt. But he thinks it looks good. To my mind it signals that he does not know how to light a room, which would be OK if he was not an electrician, bet he blames me.

    However once done you have holes in the ceiling, and so to replace you need some thing to cover the holes, I like the idea of the GX53 but they don't seem to have caught on, we see this again and again, the V2000, betamax and VHS video recorders for example, the V2000 was the best, but was first to go, and VHS was worst and last to go, so what one does not want to do is fit GX53 then find they are phased out.

    But I allowed my wife to buy a lamp for her bedroom using G9 bulbs, what a nightmare, we have wifi switches so the lights can be turned off from the bed, and first the light would not switch off, so load capacitor fitted, then they had a shimmer when on so got a packet of 10 quartz bulbs and fitted one, which stopped the shimmer, she then got 5 very large G9 LED's from internet which worked well, but one failed, so she ordered another 4, I out of interest took the failed on apart and found dry joint, and fixed, so for that 5 lamp fitting I now have 19 spare bulbs, some have never been used so goes against the grain to dump them.

    And I now have a draw full of bulbs, 20 years ago they would have soon been used up, but LED bulbs can last years, unless one of a kind then some sod made a law about that one failing, and the way the government keeps changing its mind, in 5 years time they will be saying the waste generated with LED bulbs and the problems of heating the rooms only when in use, they have decided tungsten bulbs are best, like they did with petrol and diesel cars?

    I have a 10 watt BS22d light on my landing, at 20p a kWh so switched on as we go to bed and off when we get up in the morning it will cost £4 for 5 years use, but wife still switches it off, leaves TV switched on all night, but landing light switched off.
     
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