LED flexible strip as main room lighting?

[dogfonos]

Would appreciate views or experiences on using flexible LED strip lighting as a room's main ceiling light.

I thought it would be interesting to use LED strip lighting, usually marketed as under-cabinet kitchen lighting, to illuminate a kitchen. I intend to use two long strips encased in narrow aluminium profile/channel - fitted with frosted/opaque plastic cover - each running the length of the kitchen ceiling. Anyone tried this? Any downsides (apart from deciding what power the strips need to be)?

 

[ericmark]

Quality varies so much, the standard LED lumen per watt is around 70 to 100, however some of the under cabinet lighting is down to 20 lumen per watt, all well and good to look pretty, but not as your main lighting.

What you need is a set of lamps which are driven from a fixed current supply called a driver, often around 50 volt at 320 mA, not a set of lights running from a 12 volt supply where they use a resistor to limit current, these are waste full.

It is so easy to buy rubbish, OK there is some good stuff, but also a load of rubbish, looks pretty but not much good at lighting.

 

[bernardgreen]

While it is true the resistors in the 12 volt strips do waste some power as heat it is not a great deal of heat. The driver feeding a number of LED elements in series may be more efficient but this carries the risk that one LED element failing and going open circuit will prevent the other LED elements from lighting and thus the lamp has to be replaced.

 

[Iggifer]

A lot of LED fluorescent lookalikes are exactly that, packaged up to look like a fluorescent.

Make sure you go for higher wattage stuff, 5050 LEDs at a minimum, nothing smaller for me

 

[ianniann]

Certainly possible. The difficulties are mainly practical. Cheap strips are very iffy, good ones are likely to be expensive. The ones you'll find in places like B&Q are essentially useless, so you'll have to go online. As mentioned, not especially efficient, but still on a par with many fluorescent lights. Strips with 500-1,000 lumens (really, not what they list in the specs) per meter are fairly easy to find and that adds up to a whole lot of light running along two sides of a room. Do look around for dedicated solid light strips though, since you don't actually need flexibility - if you can find the right length and styling it would be a better solution. Consider a solution with a dimmer, then get more light than you think you'll ever need. The LEDs will be dimmer in 10 years time and your eyes will be worse

 

[StephenStephen]

I've done it a couple of months ago,
The room is approx 5m by 6m, and has a large wooden beam running down the centre of the room, so I've got 5m LED running down either side of the beam.
I looked at covers, but they were going to cost almost as much as the lights and drivers, so they are sat in a long wooden L shape (approx 8mm to a side) fixed to the outsides of the beam, about 20 mm below the ceiling.
They are very bright!
I don't know how much light you'd lose in the plastic covers.

I used:
2 x 99-76-84, Integral 12V IP33 8W LED Strip Light 5 Metres (Warm White)
and
2 x 99-51-39, Integral LED 40W Constant Voltage LED Driver 200-240VAC to 12VDC (White)
from: [email protected]

I found this page on lumens helpful: http://www.integral-led.com/education/what-are-lumens

 

[ianniann]

If you don't have a cover then you may be able to see the SMDs directly. This is very unpleasant, not just because they are tiny intense dots of light, but because they will appear to have different brightnesses and colours depending on the precise angle they are viewed from. The flexible strips inevitably don't sit entirely flat so you will always be seeing some dim or yellow dots. This can be avoided by using indirect light, shining up or against the wall but not visible directly. This can be very effective but you will need to approximately double the amount of light to get the same results as direct lighting. This is entirely practical and 10m of the 120x3528 strips mentioned will give around 7,000 lumens which would be overkill for most rooms but possibly about right with indirect lighting. A diffuser over direct lighting will block around 20% of the light which can usually be ignored when calculating room lumens.

 

[aptsys]

A lot of LED fluorescent lookalikes are exactly that, packaged up to look like a fluorescent.

Make sure you go for higher wattage stuff, 5050 LEDs at a minimum, nothing smaller for me

Most of the strips out there do not have sufficient heatsinking for 5050 sized LEDs. You'll find the phosphor ages more rapidly than it should and if you find part of a strip has failed in a year or two, the colour will have shifted so much that your only option is to replace all of the LED strip in the entire room.

 

[dogfonos]

Thanks for all your views, experiences, suggestions and useful links - much appreciated.

If you don't have a cover then you may be able to see the SMDs directly. This is very unpleasant, not just because they are tiny intense dots of light

Indeed, that's why I will choose a profile fitted with an opaque/frosted cover. Even then, I'm wondering if the intensity of the narrow strip source necessary to adequately illuminate an entire room might still appear unpleasantly bright even in peripheral vision.

Most of the strips out there do not have sufficient heatsinking for 5050 sized LEDs

I thought the aluminium profile that the strips are stuck on to would act as an adequate heatsink? Yes, I'm looking at 5m of 5050 LEDs split into two separate strips (3m + 2m) for a kitchen size 4.4m x 2.8m.

Do look around for dedicated solid light strips though, since you don't actually need flexibility - if you can find the right length and styling it would be a better solution.

So far, the solid tube lighting I've seen looks a little bulky for my tastes but from what has been said here, seems more efficient than flexible LED strips. I'll keep looking.

 

[ianniann]

I don't think the light will be too intense with the frosted covers. Less than traditional bulbs and comparable to fluorescent tubes with a diffuser. Your eyes are well adapted to ignore bright light sources above eye-level.

There are two issues with heatsinking of LED strips, one is the transfer of heat from the LED itself out of the SMD, and the other where the heat goes once it is outside the SMD. 5050 SMDs are a relatively old design that is not especially well-heatsinked internally. It contains three individual diodes, essentially the same as the diodes in a 3528 SMD. When run in RGB mode, essentially with only one diode out of the three running continuously, the heatsinking is up to the job, but with all the diodes running continuously as in a white-light version they are quite stressed. Also as a fairly high-power design, a mounting on wood or plastic isn't sufficient to properly shift the heat away from the strip. Mounted on aluminium they should be OK, especially if it is a quality product. Nevertheless, I'd recommend looking for a newer design such as a 5630/5730 SMD if you really really want something that bright.

Having said all that, I think a 5050 strip will be considerably brighter than you need. It would give something approaching 1,000 lumens/m which would be a total of 5,000 for your room. If you think the room would need four traditional 100W bulbs to be properly lit, then go for it. Otherwise consider a less bright strip.

In the same vein, consider task lighting in addition to the main room lighting. Trying to provide good lighting on the work surfaces using only ceiling lights just doesn't work, not least because you're always creating shade on the working area. There really is no substitute for dedicated task lighting which you can then have at levels which would be glaring for the whole room. A good rule of thumb is 500-1,000 lux for kitchen task lighting and then only 100-200 for ambient lighting. That would mean you only need something like 1,200-2,400 lumens from your ceiling strips.

 

[Iggifer]

Most of the strips out there do not have sufficient heatsinking for 5050 sized LEDs. You'll find the phosphor ages more rapidly than it should and if you find part of a strip has failed in a year or two, the colour will have shifted so much that your only option is to replace all of the LED strip in the entire room.

That's true, but in a profile rather than attached to something else (wood, plaster etc) you have the added heat dispersal of the aluminium to help.

If you stick to not buying the cheap cheap stuff you stand a better chance. If the strip is as wide as one designed for the smaller LEDs is undoubtedly game over but the stuff I fitted in my van is about twice as wide and much thicker so fingers crossed it'll last alright - it is only my van after all

 

[dogfonos]

Having said all that, I think a 5050 strip will be considerably brighter than you need. It would give something approaching 1,000 lumens/m which would be a total of 5,000 for your room. If you think the room would need four traditional 100W bulbs to be properly lit, then go for it. Otherwise consider a less bright strip.

Using the link helpfully provided by StephenStephen in an earlier post, it appears I require around 3500 - 4000 lumens to adequately light my kitchen but, as you say, perhaps around 2000 - 2500 lumens is more reasonable for just ambient lighting. Could go bright and add a dimmer.

In the same vein, consider task lighting in addition to the main room lighting. Trying to provide good lighting on the work surfaces using only ceiling lights just doesn't work, not least because you're always creating shade on the working area. There really is no substitute for dedicated task lighting which you can then have at levels which would be glaring for the whole room.

Agree. We will have task lighting recessed into the bottom surface of all wall units. This should provide good lighting over almost all the worktop surfaces. The lighting issue I'm trying to address with one of the two strip lights (the 2m strip) is decent lighting above the sink area so, as you say, we're not working in our own shadow. The second, 3m strip, won't be positioned above anything in particular as it's just general room lighting.

If you stick to not buying the cheap cheap stuff you stand a better chance. If the strip is as wide as one designed for the smaller LEDs is undoubtedly game over

I'll curb my natural tendencies and avoid the cheap stuff. We have an LED manufacturer not far away who has these strip lights on display so I'll to pay them a visit. Aluminium profile that I like the look of:

http://www.sensio.co.uk/kitchen-lighting/profiles/Continuum.html

 

[ericmark]

While it is true the resistors in the 12 volt strips do waste some power as heat it is not a great deal of heat. The driver feeding a number of LED elements in series may be more efficient but this carries the risk that one LED element failing and going open circuit will prevent the other LED elements from lighting and thus the lamp has to be replaced.

White LED threshold voltage approx 3 volt, typical arrangement 3 LED's and a resistor so on 12 volt resistor uses 1/4 of the power. Even the mains units are often less that 100 lumen per watt so a good proportion wasted. Not sure if you can do anything about the waste however, major problem is items like dimmer switches and PIR's need power to work, so some let through power is required.

I see nothing wrong using LED strips to light a room, however one has to be careful, some of the three colour LED units have a problem that Blue, Green and Red LED's all have different threshold voltages so each colour has different value resistors so they can be used together to produce white or any other colour of light, these units do look good as an effect on the room, but at around 20 lumen per watt are little better than the tungsten they replace. Price has nothing to do with LED lighting, some people are greedy, so paying more does not mean it's good, you have to read the spec sheets.

 

[bernardgreen]

has different value resistors so they can be used together to produce white or any other colour of light,

The white balance is affected by temperature as the Vf of the three LEDs will vary with temperature if the LEDs generate the three colours directly. The effect of temperature on white balance is far less where the three LEDs all produce UV to excite coloured phosphors.

Personally I would use variable tri-colour strips for the "mood" lighting and along side them white strips for work lighting.

 

[ericmark]

Yes I agree, however the point I am trying to make is that it's so hard to select good LED lighting. To my mind any advert which does not have power used to light output some where, be it watts and lumen, or watts per lumen, and volts and amps and lumen, then it is likely rubbish.