LED lamps vs fluorescent lamps?

[Nigel Goodwin]

regarding office lighting and industrial lighting, the prevalence of fluorescent tubes shows you what is more efficient and cheaper......they wouldn't use them if leds were cheaper or more efficient.

You're confusing yourself - as I said earlier, fluorescents are considerably cheaper to install, but their running costs are a lot higher, and so are their maintenance costs.

It's false economy to fit fluorescents, LED lighting is considerably cheaper in the long term, and gives a more pleasing light as well.

I'm happily sat in my new small workshop with two LED panels in the suspended ceiling, the large revamped shop downstairs has a large number of the identical lights.

 

[Flyback]

Pocket torches and vehicle lights are directional lights, so yes, leds are great for them..........having said that, I used to work in a company that made the led headlights for Bentleys, audis etc etc.......the size of the led heatsink (and its complexity in terms of the multiple cooling protrusions) is quite phenominal.......its a big , big chunk of aluminium.
LED street lights...well,other posts on this forum have said that led is not suitable for >40W lighting. induction lamps are better...see page 9, post number #87 of this thread.........

https://www.electro-tech-online.com/threads/worldwide-lighting-made-20-more-efficienct.135162/

The average large area LED light is around 35 - 55 lumens per watt with the best putting out 70 lumens per watt whereas any induction bulb above 20 watts tends to run between 65 and 85 lumens per watt.

Plus induction lights don't need heat sinks either.

LED streetlights are only made because politicians want to trial leds out in a place where they can see them....there is the "theory" that led streetlights last longer than other forms of lighting, and they believe this may be useful for street lighting, where its an expensive pain to replace the lamps.
LED street lights can also be more easily and accurately dimmed than other lighting types....so the theory is that officials with RF dimmers, will go under each street light at night, and dim the street light until it produces just enough light, ...this will save energy overall, in spite of the fact that leds are not as efficient as induction lamps.

 

[audioguru]

The new LED street lights in my city appear to have a small whip antenna on top. Maybe they are turned on and off with RF but many of the lights are turned on during daytime so the RF doesn't work properly or is mixed up.

 

[MrAl]

Hi,

For me LED lighting just works out better all around. Maybe if i could get those small curly bulbs in cool white i might be happy with them too. I'll have to look around i guess. I also assume i will get very long life so hopefully they are designed right in the first place.

Also, i should have mentioned that i dont mind experimenting a little when it comes to new lighting and some other new technology. If it looks like it has promise and isnt exceptionally outright expensive i might give it a try to test it and see how i like it over time. Since i have found LED's in other lighting types like flashlights to be invaluable, i thought i might as well give line operated LED's a shot too.

My first encounter with this type was quite a while back now, when i got my first multi LED line operated 'bulb'. it was made from a whole bunch of small LED's mounted close together in the shape of a spot light. It was very cheap and also has a standard base. I liked it right away even though it was not that bright really. It was quite good for some uses so i used it for a few years. Made a nice desk lamp.
Now the new ones are much brighter so i am not using it now but i am sure i will again in the future.

 

[Nigel Goodwin]

Also, i should have mentioned that i dont mind experimenting a little when it comes to new lighting and some other new technology. If it looks like it has promise and isnt exceptionally outright expensive i might give it a try to test it and see how i like it over time. Since i have found LED's in other lighting types like flashlights to be invaluable, i thought i might as well give line operated LED's a shot too.

The ceiling panel lights we've fitted at work are 2 foot square, and drop in standard suspended ceilings.

They consist of a plastic diffuser sheet about 1/4 inch thick with rows of SM LED's on two opposite sides aimed into the diffuser. The LED's are connected in series parallel, and the unit is powered by an external constant current PSU.

They give a really nice pure white light, and a nice even spread - they aren't dimmable though, but you can pay more for dimmable ones.

 

[Flyback]

The ceiling panel lights we've fitted at work are 2 foot square

..yes I believe you mentioned these in a previous post,-you kindly commented that they comprise series parallel leds, and there is no limiting resistor in the series chains.
We have one at work, though I haven't been able to examine it.
I suppose the leds must be angled downward into the diffusor somehow?....it is a very nice looking light, but I bet theres a lot of light power loss in that diffusor.

 

[Nigel Goodwin]

..yes I believe you mentioned these in a previous post,-you kindly commented that they comprise series parallel leds, and there is no limiting resistor in the series chains.
We have one at work, though I haven't been able to examine it.

If it's anything like these ones, there's LOAD'S of screws to take out to get them to pieces - basically there's an L shaped cast aluminium frame, the diffuser drops in that - but isn't square, it's shorter in one direction to allow space for the LED assemblies. The LED assemblies simply drop in place at either end of the diffuser, then there's a simple aluminium plate that screws on top (LOT's of self tappers in to the frame) and sandwiches it all together.

I suppose the leds must be angled downward into the diffusor somehow?....it is a very nice looking light, but I bet theres a lot of light power loss in that diffusor.

No the LED's are mounted on thin ceramic substrates and point directly into the edge of the plastic diffuser, the top of which is covered by an aluminium plate, so all the light comes out of the bottom of the diffuser. I find diffuser technology VERY impressive, both in this case, and in LCD TV's, where the evenness of the light amazes me.

 

[unclejed613]

....high frequency electronic ballasts don't have starters......youre talking about the old fashioned 50hz fluorescents....a totally different thing.

With the HF ballasts, the tubes definitely don't flicker if the ballast is designed properly.

i had what looked like a standard fluorescent light, but had a solid state (high frequency) ballast. it lasted about 2 years. when it failed, the only fix was to replace the whole fixture, since the circuit boards were not available separately, and the switching transformers on the PCBs were what had failed (caused by dried out electrolytics and shorted transistors).

 

[Flyback]

No the LED's are mounted on thin ceramic substrates and point directly into the edge of the plastic diffuser, the top of which is covered by an aluminium plate, so all the light comes out of the bottom of the diffuser.

-seems strange that they use an aluminium plate over the whole back surface of the diffusor...surely the diffusor plastic doesn't get hot?...or maybe the aluminium is to make it structurally strong in case somebody gets in the ceiling space and puts their weight on it?..i would have thought that backplate would better be a piece of opaque plastic, or better still, plastic coated with that shiny stuff like the plastic reflectors you see above fluorescent tubes to reflect the light back down. It seems overly expensive putting a whole 2 foot square piece of aluminium there.

 

[Nigel Goodwin]

-seems strange that they use an aluminium plate over the whole back surface of the diffusor...surely the diffusor plastic doesn't get hot?...or maybe the aluminium is to make it structurally strong in case somebody gets in the ceiling space and puts their weight on it?..i would have thought that backplate would better be a piece of opaque plastic, or better still, plastic coated with that shiny stuff like the plastic reflectors you see above fluorescent tubes to reflect the light back down. It seems overly expensive putting a whole 2 foot square piece of aluminium there.

I presumed the aluminium was there basically as a reflector, but also it gives some structural strength to the assembly - and of course it's THIN - which is probably an important consideration.

 

[Flyback]

No the LED's are mounted on thin ceramic substrates and point directly into the edge of the plastic diffuser

I wonder how much light energy is lost due to the diffusor?
I believe (I know) the lights you speak of are very aesthetically pleasing, but I don't think they are meant to be very efficient at actually giving out light. I think theres a lot of loss of light power due to the diffusor?

 

[Nigel Goodwin]

I wonder how much light energy is lost due to the diffusor?
I believe (I know) the lights you speak of are very aesthetically pleasing, but I don't think they are meant to be very efficient at actually giving out light. I think theres a lot of loss of light power due to the diffusor?

Possibly?, but it's still much more efficient than fluorescents.

 

[dr pepper]

I recently fitted a load of the led panels in the canteen, similar to nige's probably, the directionality of the leds is well and truly sorted, the surface of the panel has a near contstant brightness right accross, the wattage used by 14 of these panels is less than half used by the origninal fluorescents and the light as mentioned is much more pleasing to do most things by.
The panels look as though they are a series of leds probably 1w around the edge firing into a top diffuser and then out through a bottom diffuser, some light will be lost but overall a marked improvement on the old 4 fluo tube lamops that had at least 1 tube out all the time, and the diffuser doesnt go yellow and trap dead flies, and no glass, all of these are good for a plant that handles food items.

 

[MrAl]

The ceiling panel lights we've fitted at work are 2 foot square, and drop in standard suspended ceilings.

They consist of a plastic diffuser sheet about 1/4 inch thick with rows of SM LED's on two opposite sides aimed into the diffuser. The LED's are connected in series parallel, and the unit is powered by an external constant current PSU.

They give a really nice pure white light, and a nice even spread - they aren't dimmable though, but you can pay more for dimmable ones.

Wow they do sound very nice. Are they available commercially?

Quote Originally Posted by Flyback View Post
..yes I believe you mentioned these in a previous post,-you kindly commented that they comprise series parallel leds, and there is no limiting resistor in the series chains.
We have one at work, though I haven't been able to examine it.
If it's anything like these ones, there's LOAD'S of screws to take out to get them to pieces - basically there's an L shaped cast aluminium frame, the diffuser drops in that - but isn't square, it's shorter in one direction to allow space for the LED assemblies. The LED assemblies simply drop in place at either end of the diffuser, then there's a simple aluminium plate that screws on top (LOT's of self tappers in to the frame) and sandwiches it all together.


I suppose the leds must be angled downward into the diffusor somehow?....it is a very nice looking light, but I bet theres a lot of light power loss in that diffusor.
No the LED's are mounted on thin ceramic substrates and point directly into the edge of the plastic diffuser, the top of which is covered by an aluminium plate, so all the light comes out of the bottom of the diffuser. I find diffuser technology VERY impressive, both in this case, and in LCD TV's, where the evenness of the light amazes me.

Flyback:
You dont seem to like LED's for some reason. You might be one of the few people i've ever talked to that does not like them. In fact, maybe the only one? Is there something you really dont like about them? Maybe you work for a company that makes other types of lighting

 

[alec_t]

The aluminium could also be acting as a heatsink?

 

[Flyback]

The aluminium could also be acting as a heatsink?

I hope not, that really is a problem for the diffusor if it is.
I live in UK and there is I believe just one UK owned lighting company in the UK, I think its in Wakefield, and I don't work there, or any other lighting place
I think ledlightsense make the panels or similar.

As the report says (first post), a lot of the comparisons generally heard between led and fluo are invalid.
Though those panel lights are mega expensive
**broken link removed**
£150 for a 44w light panel is not a nice price.

 

[alec_t]

I hope not, that really is a problem for the diffusor if it is

I doubt it. The large surface area of the ali would make it a pretty efficient heatsink, so its temperature could be well below anything likely to damage the diffusor.

 

[Flyback]

I should have explained better, -I meant that if the diffusor is getting so hot that it needs a heatsink then that means the luminaire has problems.

If diffusors do take some of the energy out of the light, does that mean it turns to heat and heats up the diffusor?

 

[Nigel Goodwin]

Wow they do sound very nice. Are they available commercially?

Yes, we bought them commercially - they came from a company in Leicester, UK - but are made in China

 

[Nigel Goodwin]

I should have explained better, -I meant that if the diffusor is getting so hot that it needs a heatsink then that means the luminaire has problems.

They don't run hot, the only components inside are the LED's and some SM resistors and those are right at the edge, any heat goes in the aluminium frame.

The aluminium is a reflector, as I said.

However - what you don't want to do is run them disassembled - they are seriously BRIGHT!!. I had one in pieces looking for a dry joint (one chain of LED's was intermittent, giving a darkish patch in one corner). Initially I just powered it up, but it was so bright it was impossible to work on - so I ran it from a variable supply via a current limiting resistor, and adjusted it for a sensible level, and soon found the dry joint on one of the LED's.