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Light bulb types

Does what it says on the tin
UncleEbenezer
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Light bulb types

#281680

Postby UncleEbenezer » February 2nd, 2020, 12:57 am

A round tuit here is to replace lots of recessed lights with LED bulbs. Daylight style for downstairs, something warmer upstairs. Particularly in those rooms where they get lots of use.

I'm slightly daunted by the fittings: how to get the 35W and 50W halogen bulbs out and replace them. Every light I've worked with before has seemed much more accessible! But mostly I'm concerned about getting the right bulbs: these fittings are something I haven't seen before.

Trying to do my research online, they look like either MR16 or GU5.something. I've no idea what those mean, nor whether there are other lookalikes that might be confusing me. There's one specimen here that claims to be MR16 in its webpage but GU5.3 when I download its data sheet. I think I saw another "looks right" on another site calling itself GU5.4. They all seem to be 12V DC, which is also what the old bulb I've extracted says of itself.

Any tips on what to look out for?

Lanark
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Re: Light bulb types

#281743

Postby Lanark » February 2nd, 2020, 2:56 pm

Well now that we are out of the EU Im sure we'll soon be able to just buy nice 150W "made in britain" incandescents again!

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Re: Light bulb types

#281763

Postby gryffron » February 2nd, 2020, 5:38 pm

GU5.3 defines the socket. 2 small pins 5.3mm apart.
MR16 defines the physical dimensions of the bulb. 2" across.
Then you need to check it is the correct voltage.
Then the brightness and colour

Gryff

bungeejumper
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Re: Light bulb types

#281780

Postby bungeejumper » February 2nd, 2020, 6:46 pm

Usual procedure with old-style recessed spots is to look for the metal retaining ring that sits between the rim and the bulb, and compress it by closing the gap in the ring with a couple of small screwdrivers or needle nosed pliers. Then it should all pop (i.e. fall) out.

At this point you'll know whether you've got a 12 volt lighting system or a 230 volt one. (It's printed on the bulbs.) You'll also know what kind of pins your bulbs have got. Two short straight stabbing pins, as Gryffon describes, or a kind of bayonet (G10). Which you remove by twisting the bulb, as you'd expect, except that it can be a bit of a fiddle.

The downlighter fitments are spring-fitted into the ceiling, and you basically coax them out without using too much brute force. (Youtube is your friend.) Low voltage lights will (usually!) have a transformer the size of a Mars bar attached to each light fitting. And they're a bit out of favour these days - they can overheat, so if in doubt, there's a lot to be said for replacing the downlighter fitments with mains fitments.

They're very cheap - my kitchen set of six cost about £35, and they were the safer FIRE variety that are now recommended for any room where there's living accommodation overhead. Mine were the Lumilife fittings from LED Hut. Doddle to fit, but make sure they're not wider than the ceiling holes that you've already got.

Oh, and if you're using a dimmer switch, make sure you get dimmable bulbs.

Apologies if this is more than you wish to know. Anything else? Fire away.

BJ

UncleEbenezer
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Re: Light bulb types

#281799

Postby UncleEbenezer » February 2nd, 2020, 7:54 pm

Thanks gryff for the straight and clear answer. And thanks BJ for elaborating: I've already done most of what you suggest, but the bit about 12V bulbs (which is what they are) being out of favour is certainly food for thought. Seems they are both MR16 and GU5.3 'cos those refer to different attributes. And yes I also have various GU10 spotlights. Oh for the days when you just had to check whether it was bayonet or screw!

Damn, one of my primary targets is the nine recessed lights in the kitchen, which I had in mind to replace with daylight LEDs. But also on the agenda at some point is a new kitchen: perhaps I should just include the lighting in the design of that. Now I'll end up procrastinating even more :evil:

bungeejumper
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Re: Light bulb types

#281896

Postby bungeejumper » February 3rd, 2020, 11:13 am

UncleEbenezer wrote:Damn, one of my primary targets is the nine recessed lights in the kitchen, which I had in mind to replace with daylight LEDs. But also on the agenda at some point is a new kitchen: perhaps I should just include the lighting in the design of that. Now I'll end up procrastinating even more :evil:

FWIW, replacing my six 12v fitments with mains LEDs took about an hour and a half, and I was finished by lunchtime. You just pull out the transformer (which hopefully has been cabled with enough slack :|), and disconnect it at the mains cable end, and reconnect said cable to the connector strip on the fitment, and push the new downlighter into the hole and you're done. Except that you'll probably want to paint the ceiling at this point. ;)

When I said low voltage was out of favour, what I should have added was that the mars bar transformers have a limited life expectancy of anywhere between six weeks and six years - you can never tell - but you can absolutely bank on one of them giving out at exactly the wrong moment. My daughter's failed the day before she put her house on the market, plunging the kitchen into a dodgy sort of half-light. Cue a panicky call to dad. She sold the house immediately. Tadaaaaa, that's what parents are for.

BJ

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Re: Light bulb types

#281925

Postby taylor20 » February 3rd, 2020, 12:33 pm

bungeejumper wrote:
UncleEbenezer wrote:Damn, one of my primary targets is the nine recessed lights in the kitchen, which I had in mind to replace with daylight LEDs. But also on the agenda at some point is a new kitchen: perhaps I should just include the lighting in the design of that. Now I'll end up procrastinating even more :evil:

FWIW, replacing my six 12v fitments with mains LEDs took about an hour and a half, and I was finished by lunchtime. You just pull out the transformer (which hopefully has been cabled with enough slack :|), and disconnect it at the mains cable end, and reconnect said cable to the connector strip on the fitment, and push the new downlighter into the hole and you're done. Except that you'll probably want to paint the ceiling at this point. ;)
...
BJ


Just to add, always use a qualified electrician if in any doubt, and I'd recommend turning off the electirc before performing any of these tasks, etc. etc.

You may be unlucky in that I had one transformer powering several downlights using 12V cables, so replacing may involve significant more 'jiggery pockery', running 1.5mm cable to all downlights.

I also thought is it is GU10 fitting it is always 240v ?

bungeejumper
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Re: Light bulb types

#281930

Postby bungeejumper » February 3rd, 2020, 12:56 pm

taylor20 wrote:You may be unlucky in that I had one transformer powering several downlights using 12V cables, so replacing may involve significant more 'jiggery pockery', running 1.5mm cable to all downlights.

I've heard of that, but I've never seen it personally. Apart from the fact that having one big transformer in the middle seems like putting all your eggs in one basket ("one out, all out"), those 12 wires are each carrying four amps over longish distances.

Also, if I (dimly) recall rightly, you had make sure that each 'spoke' of the cabling from the transformer to the various light fittings was the same length as all the others, or else you'd find that resistance would dim the furthest ones but not the ones near to the transformer. No wonder that system wasn't popular.

BJ

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Re: Light bulb types

#281931

Postby swill453 » February 3rd, 2020, 12:59 pm

taylor20 wrote:I also thought is it is GU10 fitting it is always 240v ?

Yes, he said he had 12V lights and GU10s.

Scott.

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Re: Light bulb types

#281959

Postby UncleEbenezer » February 3rd, 2020, 3:02 pm

bungeejumper wrote:
UncleEbenezer wrote:Damn, one of my primary targets is the nine recessed lights in the kitchen, which I had in mind to replace with daylight LEDs. But also on the agenda at some point is a new kitchen: perhaps I should just include the lighting in the design of that. Now I'll end up procrastinating even more :evil:

FWIW, replacing my six 12v fitments with mains LEDs took about an hour and a half, and I was finished by lunchtime. You just pull out the transformer (which hopefully has been cabled with enough slack :|), and disconnect it at the mains cable end, and reconnect said cable to the connector strip on the fitment, and push the new downlighter into the hole and you're done. Except that you'll probably want to paint the ceiling at this point. ;)

Heh. The kitchen ceiling could use some minor repair. When I first moved in, I found water from the shower came down through it. But no visible damage there that polyfilla and paint won't fix.

Looking into the lights, I don't see those mars bars. Come to think of it, I don't even know the size of a mars bar these days: it's been too many decades since I had one. But I think if I do more than replace the bulbs, I'll want to delegate to an electrician. Or at the very least, leave it a couple of months to the season of daylight!

When I said low voltage was out of favour, what I should have added was that the mars bar transformers have a limited life expectancy of anywhere between six weeks and six years


These almost certainly date back to when the building was converted to houses, over 20 years ago. My dad's house is of a similar vintage, and has the same lighting: evidently it was popular at the time.

Is there a risk that a transformer made for a 35-50W halogen bulb might misbehave if faced with a ballpark-6W LED?

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Re: Light bulb types

#281963

Postby bungeejumper » February 3rd, 2020, 3:16 pm

If you know for sure that your bulbs are 12v but you can't see the mars bars (which should be no more than 12 inches away from each downlighter fitting, stuffed away on a loose length of cable), you might be better advised to get some help. :(

UncleEbenezer wrote:[Is there a risk that a transformer made for a 35-50W halogen bulb might misbehave if faced with a ballpark-6W LED?

You shouldn't normally need a transformer at all - most kitchen LED downlighters run on 230 volts and wouldn't take kindly to the offer of a paltry 12v. There are 12v LED downlighters available (https://www.amazon.co.uk/slp/12v-led-do ... 8sng6pm9pq), but they're mainly intended for use in boats and caravans.

BJ

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Re: Light bulb types

#283326

Postby redsturgeon » February 9th, 2020, 8:36 pm

It seems likely you have a substantial transformer somewhere in the ceiling running those mr16s and you should be able to swap straight to led mr16s in their place, since they will be drawing far less current than the old halogens. GU10 can easily be replaced with GU10 leds.

John

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Re: Light bulb types

#283395

Postby UncleEbenezer » February 10th, 2020, 10:41 am

Update: I got around to buying a single 330-lumen LED bulb in what looked the right form. Tried it in the hallway, where it turned out a little too bright. So tried it up in the attic room (aka my office - the one room where I sit for hours with the ceiling lights on), where it was just right. Bought four more the same to complete the row of five along the centre of the ridge.

The one at the door end of the loft room won't work. Or rather, when I turn it on, it flashes momentarily then goes out. The same bulb in another fitting is fine. Another LED bulb in the same fitting has the same trouble. But re-attaching an old 50W bulb there, it works as before. The other four - which are ample for my needs - work fine.

Since my local shop has just the one choice of LED of the relevant form factor, I shall have to source dimmable LEDs (sitting room&bedroom), lower-light LEDs (hallway), and bright daylight LEDs (kitchen - unless I change my mind) online.

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Re: Light bulb types

#288789

Postby csearle » March 5th, 2020, 8:59 pm

UncleEbenezer wrote:The one at the door end of the loft room won't work. Or rather, when I turn it on, it flashes momentarily then goes out. The same bulb in another fitting is fine. Another LED bulb in the same fitting has the same trouble. But re-attaching an old 50W bulb there, it works as before. The other four - which are ample for my needs - work fine.
Scandalously I haven't read through your thread here fully but from what you say above I am wondering if the one at the door end of the loft room has a different driver/e-transformer from the rest, which might cause differing behaviour? C.

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Re: Light bulb types

#288844

Postby DrFfybes » March 6th, 2020, 9:37 am

csearle wrote:
UncleEbenezer wrote:The one at the door end of the loft room won't work. Or rather, when I turn it on, it flashes momentarily then goes out. The same bulb in another fitting is fine. Another LED bulb in the same fitting has the same trouble. But re-attaching an old 50W bulb there, it works as before. The other four - which are ample for my needs - work fine.
Scandalously I haven't read through your thread here fully but from what you say above I am wondering if the one at the door end of the loft room has a different driver/e-transformer from the rest, which might cause differing behaviour? C.


I suspect the "dodgy" one has a transformer with a minimum load as well as a maximum.
Some transformers need a load to operate, and AIUI shut down if no load is detected. This means if you swap your 10W halogens in your lounge fitting for LEDs the total load on your 20-150 W transformer drops below 20W and it shuts down so needs to be replaced with one that runs from 0W like this

https://www.tlc-direct.co.uk/Products/LTYT210.html

Either that or put 3 of the 10W ones back in to raise the load ;)

Paul


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