LEDs … The Good, The Bad, and The Ugly

[Neil WyattModerator @neilwyatt]

Michael,

While I agree about bare-LED lamps, how is a fully-enclosed LED lamp more dangerous than a glass envelope filament bulb or a fluorescent?

All of them will expose live contacts if broken, but only the LED lamp would have anything in series to limit the current.

Neil

Edited By Neil Wyatt on 26/09/2014 09:38:27

Edited By Neil Wyatt on 26/09/2014 17:40:34

[Michael GilliganParticipant @michaelgilligan61133]

Neil

Fair point … my answer would be the concern about build-quality.

If I recall correctly; Machine Lighting was supposed to be either SELV or driven from a Safety Isolating Transformer.

There have been several suggestions; on this forum and elsewhere, that GU10 desk lamps might make cost-effective machine lights.

All I ask is that people consider the implications.

MichaelG.

Edited By Neil Wyatt on 26/09/2014 17:40:30

[Michael GilliganParticipant @michaelgilligan61133]

On the subject of build-quality:

I was reluctant to pst this one, because the author apparently made an error when he "reverse engineered" the schematic … but the salient points regarding Quality/Safety are very well illustrated, so look here.

MichaelG.

Edited By Neil Wyatt on 26/09/2014 17:40:19

[VersabossParticipant @versaboss]

Not that it seems I'm not interested in that LED discussion. In fact I am, as a couple of these outdoor floodlights are under way to me. I hope they are bang good! Link seems to work very slowly, so have patience!

So may I propose that these LED discussions ace collected into a dedicated new thread? Nobody will find them again in this one…

Kind regards, HansR.

 

Edited By Neil Wyatt on 26/09/2014 17:40:25

[Michael GilliganParticipant @michaelgilligan61133]

[Michael GilliganParticipant @michaelgilligan61133]

Following recent discussion on the "What did you do today" thread, I am starting this one as a general repository for comments and links about LEDs.

Please contribute; but please try to keep it relevant.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Versaboss on 26/09/2014 13:49:12:

… may I propose that these LED discussions ace collected into a dedicated new thread? Nobody will find them again in this one.

.

An excellent point, HansR.

I have just started a new thread, and shall be happy for one of our Moderators to move [or copy] my recent posts on LEDs to that thread.

MichaelG.

Edited By Neil Wyatt on 26/09/2014 17:38:22

[Nick_GParticipant @nick_g]

.

As a licensed radio amateur I consider them to be nothing short of the work of the Devil himself.!

Many of them from dubious geographical origins (that's most of them then) scatter RFI to infinity an beyond. There is no way if the import laws that are in place regarding such were even half enforced they would be allowed into the country.

Many have a badly designed and manufactured switch mode power supply that is the problem. This also extends to many other items sold.

Regards, Nick-Victor-Meldrew

[Geoff TheasbyParticipant @geofftheasby]

As another radio amateur I can confirm that. the cheap ones are the worst, as the manufacturers leave out the interference suppression components (sometimes even the safety bits) after the things have been CE tested, or even just mark them CE without authority, as there is no regulation on the use of the mark. Good ones might be OK, but a quality manufacturer will be able to show you the test results. Well-known names in the industry might be OK, but check, and be prepared to pay!

Geoff

[Nick_GParticipant @nick_g]

Posted by Geoff Theasby on 26/09/2014 16:01:06:

and be prepared to pay!

Geoff

We and other members of this forum may well be prepared.

Unfortunately people living a few doors away probably will not. RFI is no respecter of fence lines.

Nick

[John ShepherdParticipant @johnshepherd38883]

To put things in perspective – there is is nothing much wrong with LEDs. They have come along way from being (red) low level indicators to now providing satisfactory levels of illumination with a spectrum that suits many applications, use less power and run relatively cool.

I do agree though that the way they are powered can be an issue. When 240v LED lamps first became available, I seem to remember that the interference from from the in built power supply in some of them wiped out DAB radio reception in the home. Now, in my office I have a reading lamp with an LED lamp close to a DAB radio and there is no problem. If one buys lamps from established reputable manufacturers that have a history of supplying the UK, one would hope that the safety issues highlighted (that are a serious concern) are not present.

If we are considering low voltage (12v) LED arrays, then we have a choice when selecting a suitable and safe power source that is up to the job. The problem of interference and safety becomes more of an issue when we try to do things 'on the cheap'. I know it is sometimes difficult and for instance I would not have a 'wall wart' plug in power supply in the house if I had a choice. My main aversion to the older ones is that the weight tends to cause them to not stay secure in a wall socket, the newer lightweight switch mode types overcome this but can cause interference, suffer poor reliability and I believe carry a higher fire risk if they fail.

It is doubtful if we can have much influence on preventing people from buying rubbish but if we do it right, there is no reason not to take advantage of LEDs in the home and in the workshop when there use is appropriate.

John

[V8EngParticipant @v8eng]

I have a PIR LED Floodlight on the rear wall of my house, it's been working for several months, reading this thread has got me worried now.

Edited By V8Eng on 26/09/2014 19:35:38

[Les Jones 1Participant @lesjones1]

Hi all,
One thing I noticed on a 10 Watt mains voltage floodlight that I bought as that it was only fitted with 2 core cable. I would recommend fitting 3 core cable and connecting earth to the metal case. As the PCB was just floating loose and just insulated with heatshrink sleeving a short to the case would make it live. Better for it to trip the RCD or MCB rather than electrocuting someone. The units that versaboss posted a link to also appear to be fitted with 2 core cable.

Les.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Shepherd on 26/09/2014 16:52:00:

…

If we are considering low voltage (12v) LED arrays, then we have a choice when selecting a suitable and safe power source that is up to the job. The problem of interference and safety becomes more of an issue when we try to do things 'on the cheap'.

…

It is doubtful if we can have much influence on preventing people from buying rubbish but if we do it right, there is no reason not to take advantage of LEDs in the home and in the workshop when there use is appropriate.

.

John,

That's an excellent summary of the situation as I see it.

I do have some LED "household lightbulb" replacements [from IKEA and from B&Q], all of which are performing admirably, so far.

However: My main interest in LEDs is for Microscope Illumination and I have a very strong preference for battery powered devices in that situation.

I have done some preliminary testing on a 20W LED, with a view to using one or more of them as a Fibre Optic Illuminator … Given that the light output from LEDs is essentially cold; it's surprising how much heat is generated from the back of the device [effectively, of course, it's the vast majority of the input power]. This thing will need a serious heatsink! … This is also true of the GU10 lamps that we have been discussing, and I suspect that the heat build-up within typical domestic lamp-holders may be greater than users expect. Add that to "economy" construction, and the prognosis is not good.

I have a small "non-contact" thermometer on order, so should be able to do some quick'n'dirty experiments.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 26/09/2014 21:59:17:

I have done some preliminary testing on a 20W LED, with a view to using one or more of them as a Fibre Optic Illuminator … Given that the light output from LEDs is essentially cold; it's surprising how much heat is generated from the back of the device [effectively, of course, it's the vast majority of the input power]. This thing will need a serious heatsink! …

.

Sorry, just spotted my silly typo. The LED under test is 10W not 20W

… and, for completenes, I should mention that it is actually an array of nine LED elements arranged in a 3×3 grid within a large "puddle" of phosphor.

MichaelG.

[Ian S CParticipant @iansc]

Les, I wrote earlier of my mains powered 10 Watt flood light with RFI problems, I cured it with a small isolating transformer.

Ian S C

[Rod AshtonParticipant @rodashton53132]

Big ask.

For the non-electrical!! Just trying to get my head around a lighting scheme to put into a new workshop.Was planning to go with L.E.D. Now in fear and trepidation after reading all the posts.

Please,could anyone make slightly more specific recommendations on what actually is safe to buy. (U.K.) Or perhaps share your system configuration?

Need to fit both general lighting and specific machine lighting.

Confused!!

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Rod Ashton on 28/09/2014 10:50:47:

Big ask.

For the non-electrical!! Just trying to get my head around a lighting scheme to put into a new workshop.

.

Rod,

It's a very reasonable question.

For what it's worth; here is my personal recommendation:

• For the general lighting, B&Q Diall LP-A65-1S 9W bulb [this is the bayonet-fit version, the Edison Screw version presumably has a different number] … These are easily the equivalent of a 100W 'Pearl' incandescent bulb, and appear to be well built and free from troublesome Radio Frequency Interference.
• For local lighting [especially on or near machines], install a 12V circuit powered either by a Sealed Lead Acid Battery or a good quality Mains Power Supply. Then use G5.3 or G4 lamps, or any of the Automotive bulbs.

Others' recommendations may differ … but that's the direction I am taking.

MichaelG.

[John ShepherdParticipant @johnshepherd38883]

John Lewis have good prices on Philips lamps, also much cheaper than the own brand Diall from B&Q the last time I looked.

Please don't use a lead acid battery charger. The voltage is not smoothed and additionally can go well above the 12 volts needed if not connected to a battery.

[MuzzerParticipant @muzzer]

By law, any product sold in Europe has to be CE marked and that means that the manufacturer has to self-certify that they have carried out all the applicable tests (and that the product passed). The penalties are quite severe, so if you buy from a reputable supplier (= UK high street name) you should be reasonably safe.

The stds apply to the safety clearance distances, materials used, flammability of materials, manufacturing processes used etc as well as EMC (including RFI). That's partly to ensure that the safety insulation between the dangerous high voltage parts and user-accessible parts is adequate under all conditions, no component failure will compromise its integrity and it will not propagate fire. Of course, the same approvals stds apply to battery chargers and power supplies, so simply moving to battery power (which requires recharging) may not result in a safer system in terms of shock and fire.

Buying electrical lighting compts directly from China is probably not the right thing to do, even if they appear to sport some sort of CE marking. Most of these concerns should be met if the bulbs etc are bought from reputable suppliers in the UK / EU. IKEA, B&Q etc sound like good places to start.

The lamp in the video is horrific and there is simply no way you would ever get it approved. I suspect anybody who tried to sell this in the UK might even risk criminal prosecution.

Murray

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Shepherd on 28/09/2014 17:36:07:

Please don't use a lead acid battery charger. The voltage is not smoothed and additionally can go well above the 12 volts needed if not connected to a battery.

.

Agreed 100% John

The typical Lead-Acid Battery Charger does not equal "a good quality Mains Power Supply"

MichaelG.

[paul raynerParticipant @paulrayner36054]

If anyones interested they are selling 5w GU10 led bulbs at wickes for £3.99 each

regards

paul

[Michael GilliganParticipant @michaelgilligan61133]

For info … I've just found the OEM of the Diall lamps; and it appears that they also manufacture for Philips.

Interesting times we live in.

MichaelG.

[WALLACEParticipant @wallace]

I recently bought some cheap and cheerful 12 volt MR16 led bulbs to turn into bike lights from ebay – incidently all UK suppliers – and deliberately broke the glass away to free up the circuit board with the leds mounted on them.

The red lights had a small bridge rectifier plus a current limiting resistor on the boards, the two white ones were a lot more sophisticated with a separate small pcb with not only rectifiers but a small surface mounted chip, various resistors plus an electrolytic capacitor and inductor.

So they must be ok to run on ac – and I would imagine the white ones would be fine with a few volts either way as well. They weren’t dimable ones which presumably won’t vary much in brightness with input voltage – I must admit I only ran them on 12v dc.

An unregulated nominal 12v ac supply should therefore fine ..IMHO !

W.

W.

[Les Jones 1Participant @lesjones1]

Hi Wallace,
I too have dismantled some some MR16 LED lamps. I think you will find that the chip is an MC34063 switch mode voltage regulator. (Or similar.) The ones I took apart used the over current protection sensing to control the LED current which is not very accurate as it senses the input current. I think they used them this way to avoid the 1.25 volts that would be required across a current sensing resistor in series with the LEDs if the chip was used in its normal mode. The larger "Home Bargain" shops sell 5 watt G10 LED lamps. I have bought some that seem to work well and reliably at about £3.00 each. Last time I looked they had then for 2 for £5.00 but they were a different design. I have not tried these.

Les.

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