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Old 27th Jan 2019, 10:26 am   #21
Herald1360
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Default Re: A Quick Question about Halogen to LED conversion

Is this lamp on for long periods, or just when the door's in use? If the latter, why bother changing, the energy saving will be minimal? Downsize to a 35 or 20 watt bulb and buy a few spares whilst they're cheap- you know how long the bulbs last, so go figure.....

If it is on 24/7 or even 8/7, then follow the suck it and see, followed by fitting a suitable fitting for a mains voltage LED if necessary route.
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Old 27th Jan 2019, 10:35 am   #22
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Default Re: A Quick Question about Halogen to LED conversion

With intermittent use, I calculated that the conversion cost would be covered in two years.
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Old 27th Jan 2019, 12:29 pm   #23
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Default Re: A Quick Question about Halogen to LED conversion

A traditional copper and steel transformer will be fine powering a lower load. An electronic "transformer" (really a switched-mode power supply) probably will sit there, flashing the light on and off. What usually happens is the primary side has to cut the duty cycle so low in order to limit the output voltage (real filaments would draw enough current to pull it down lower, due to resistive losses in the secondary winding; rather than just use thicker wire to wind the secondary, they just designed the circuit with the assumption in mind that these losses were inevitable) that not enough energy makes it into the sustain winding to keep the oscillator powered. It then shuts down, and has to wait for the startup capacitor to recharge.

If anyone else has run afoul of this problem with electronic SELV lighting transformers at low loading, a turn off the secondary would fix it if you could get at the transformer and the secondary was outermost. File this under "Definitely worth a punt if desperate".
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Old 27th Jan 2019, 12:38 pm   #24
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Default Re: A Quick Question about Halogen to LED conversion

My quick rule of thumb is that 1 watt switched on 24/7 will cost £1/year to run. So a 50W bulb on continuously will cost £50/year. If it’s on less than continuously, derate accordingly, so if it’s on 8/7, ie 1/3 of the time, it’ll cost £17/year.

I did this sum based on electricity costing 11p/kWH. Its gone up since then, but if you assume the sum gives the saving by switching to LEDs rather than cost compared to no light, you’re in the right ballpark to see how long switching to LEDs will take to recover their cost.

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Old 27th Jan 2019, 12:47 pm   #25
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Default Re: A Quick Question about Halogen to LED conversion

Thanks, everyone. I didn't expect it to get this complicated!

No, the light has intermittent use, maybe three or four hours each night. The bulb is at least six years old, and I just wanted to know what to replace it with. The supermarket I go to no longer sells halogen bulbs at all.

Here's a pic of the label on the transformer.
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Old 27th Jan 2019, 2:57 pm   #26
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Default Re: A Quick Question about Halogen to LED conversion

I until recently had a strip of six in the lounge. It was definitely a conventional transformer and was no problems to replace them all with MR16 equivalent LEDs.

In the bathroom I replaced 8 35W MR16s. Now here I have an electronic switcher supply. So at the time I did some digging and Philips made an LED equivalent that was reported to work fine, and indeed they do. Maybe being older LEDs they are less efficient and therefore are OK? Anyway I have had them in there for probably ten years.

Whichever way you look, it's not a foregone conclusion that you can't do it.

One other comment. When I fitted an identical power unit to that above, and again 8x35W, in the downstairs cloakroom, I had problems. The power unit would flicker and only slowly turn on. Current limiting on cold filaments. Remove 1 and it was fine, even though the total load was well within the rating. I got a replacement and it was just the same. Trouble was I'd used nice thick cable, and there wasn't much of it because it's a small room. Added in a bit of extra length before the first fitting, and all was well.
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Old 27th Jan 2019, 3:00 pm   #27
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Default Re: A Quick Question about Halogen to LED conversion

Quote:
Originally Posted by Lancs Lad View Post
Thanks, everyone. I didn't expect it to get this complicated!

No, the light has intermittent use, maybe three or four hours each night. The bulb is at least six years old, and I just wanted to know what to replace it with. The supermarket I go to no longer sells halogen bulbs at all.

Here's a pic of the label on the transformer.
I'd be pretty sure that's a conventional transformer given that the output is quoted as AC. MR12 LEDs are so cheap its got to be worth trying one. Have a think about what colour you want as the cool white ones can be quite blue and not warm like the Halogen.
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Old 27th Jan 2019, 3:21 pm   #28
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Default Re: A Quick Question about Halogen to LED conversion

Quote:
Originally Posted by Hartley118
Our family bathroom has multiple 12V 50W halogen spots, each one fed from one of those common yellow electronic transformers. These too I'm progressively changing to the LED equivalents as they expire. Again, despite using electronic transformers, the changeover has been totally trouble free.
If there are several halogens run in parallel from one electronic transformer then you can probably get away with replacing all but one of them with LEDs. Replace the last one with an LED and you may get trouble.
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Old 27th Jan 2019, 3:24 pm   #29
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Default Re: A Quick Question about Halogen to LED conversion

We still do not know for certain if the transformer is a traditional copper/iron type or a more modern electronic transformer.

It does however appear ALMOST certain that it is the older copper iron style.

If that is the case, then a standard MR16 LED lamp should be fine, these are widely sold and are not expensive.
Cool white or warm white according to preference.

You will still be paying for the iron losses in the transformer, but despite this will still achieve a worthwhile energy saving, and hopefully a longer lamp life.

A 12 volt 50 watt halogen lamp will probably use about 60 watts in total, lamp wattage plus an estimated 5 watts copper loss and 5 watts iron loss.

A 5 watt LED lamp will probably use about 10 watts in total, lamp wattage plus 5 watts iron loss. The copper loss will be minute at such a reduced load.
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Old 27th Jan 2019, 4:03 pm   #30
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Default Re: A Quick Question about Halogen to LED conversion

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Originally Posted by G8HQP Dave View Post
If there are several halogens run in parallel from one electronic transformer then you can probably get away with replacing all but one of them with LEDs. Replace the last one with an LED and you may get trouble.
No, each lamp in our bathroom has its own electronic transformer, but they're of a mid-1990s generation which may be more tolerant than more recent ones.

However, in this instance if the transformer is, as described, relatively weighty, it's unlikely to be electronic. Little to lose by just trying out an LED lamp. Proof of the pudding etc......

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Old 27th Jan 2019, 8:27 pm   #31
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Default Re: A Quick Question about Halogen to LED conversion

The language used on the sticker shown on the transformer in post 25 seems to suggest that it is a traditional steel-cored transformer with separate primary and secondary windings (not an autotransformer) and fitted with a thermal fuse. If it weighs like there is a hefty lump of metal occupying most of the inside of it, that's probably what it is.

Definitely try it with an LED lamp before you write it off as unsuitable. Even if it is electronic, they don't all do the pulsing thing with LED loads, and you won't cause any lasting damage.
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Old 27th Jan 2019, 8:36 pm   #32
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Default Re: A Quick Question about Halogen to LED conversion

If it was me I would just replace the whole fitting. That way you got a no nonsense. It just works saves you money. Get a good make for about £22 ish and you also get great light output low running cost and a 5 year or more guarantee.
Job done and no ifs and buts it works Andy
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Old 28th Jan 2019, 2:44 am   #33
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Default Re: A Quick Question about Halogen to LED conversion

Re post 25, with a membership so technically proficient Lancs Lad, it's always complicated with the same things repeated but with only one bulb to fix, you can shut things down right away! Just try it out!

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Old 28th Jan 2019, 10:50 am   #34
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Default Re: A Quick Question about Halogen to LED conversion

That's sound advice, Dave!

Many thanks to everyone who took the time to reply
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Old 28th Jan 2019, 10:57 am   #35
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Default Re: A Quick Question about Halogen to LED conversion

Looks like a traditional transformer - manufacturer lists it as 1.2+ kg

http://php2.twinner.com.tw/site/prod...ssify_SN=15619

I had a somewhat similar question last year, for a lounge light, with a traditional toroidal transformer and multiple 20W halogens in parallel. They were all simply swapped for low wattage LED replacements, that have worked perfectly ever since, with the added 'perk' that the LED bulbs are warrantied for 5 years.
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Old 28th Jan 2019, 4:00 pm   #36
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Default Re: A Quick Question about Halogen to LED conversion

Like Goldie99, I have two sets of five 12V, 20W MR16 eyeball halogens in the bedroom, each set driven by a conventional 50Hz 12V secondary mains transformer. The difference is that the transformers are fed from a dimmer switch designed for inductive load dimming and slow ramp up and down (made by Danlers IIRC). I have been wondering whether the dimmer function will still work if I substitute LED lamps in place of the halogen. Maybe this will only work with specific 12V a.c. LEDs.
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Old 29th Jan 2019, 10:12 am   #37
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Default Re: A Quick Question about Halogen to LED conversion

There is absolutely no quick answer to LED lighting especially when retrofitting ELV (12v). I have had some success with dimming using the Varilight V-Pro LED Dimmer Switch which allows you to set it for leading or trailing edge transformers by doing a "program" with a series of steps.
Dimming of 12v LEDs can be tricky in that they may dim partially and then suddenly cut out.
The main problem I come across in my work is when individual transformers have been replaced with different ones and none of the LED lamps match because the technology changes so fast. You then have mismatches and the lamps dim inconsistently and cut off at differing brightnesses.
Flicker is a never ending problem and can be caused by external influences (household appliances) as well as mismatches and incoming mains borne interference.
Colour temperature is in the eyes of the beholder.. warm white is my preference but some people prefer a crisp white. And warm white with one manufacturer will hardly ever be the same with another.
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Old 29th Jan 2019, 12:46 pm   #38
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Default Re: A Quick Question about Halogen to LED conversion

Am I missing something here ?

..or why don't you just dump the MR16 and it's transformer and install a G10 mains unit (same dimensions as an MR16), depending on where you shop you could probably get the down lighter unit and led bulb for under a tenner
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Old 29th Jan 2019, 2:10 pm   #39
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Default Re: A Quick Question about Halogen to LED conversion

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Am I missing something here ?

..or why don't you just dump the MR16 and it's transformer and install a G10 mains unit (same dimensions as an MR16), depending on where you shop you could probably get the down lighter unit and led bulb for under a tenner
There's an echo in here!
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Old 29th Jan 2019, 2:35 pm   #40
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Default Re: A Quick Question about Halogen to LED conversion

I use 6 of these in our (smallish) kitchen, and have been absolutely delighted.

Double insulated so don't even need an earth connection.

https://www.screwfix.com/p/enlite-e8...220-240v/3631x

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