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## switchlighting

18 posts

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Lets assume we want the efficiency from a 3000K light (assume the led die temp is 85 deg C)

Here are the incorrect ways (but most common) in order of how wrong it is.

- 1000 lumen / 10 watts = 100 L/watt (it will say on box "for 5000k led")
- 850 lumen / 10 watts = 85 L/watt
- 1000 lumen / 13 watts = 77 L/watt (it will say on box "for 5000k led")
- 850 lumen / 13 watts = 65 L/watt

(To stay competitive we have also had to published efficiencies based on the above)

The correct way is as follows:

(750 x .9 x .91) /13 = 47L/watt

The best way is to have the light output measured by a integrating sphere to calculate the output lumen.

In practise it is not easy to make a focused dimming light with an efficiency over 60 - 65 L/watt

## timmmay

13237 posts

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switchlighting:
The correct way is as follows:

(750 x .9 x .91) /13 = 47L/watt

Assuming 750 is lumens you have two magic numbers in there... what are .9 and .91, and where did you get them from?

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## switchlighting

18 posts

Geek

lens loss = 0.1 so multiply by 0.9
Glass loss = 0.09 so multiply by 0.91

These are approximate real life losses.

## CYaBro

2796 posts

Uber Geek

timmmay: I think it's these ones, but the Lighting Direct website seems to be down. It's these ones, in white. 11W, 600 lumen, 54 lumen per watt. I wasn't that bothered about absolute efficiency, they're nice looking lights that are bright enough and use less power than most others. If I was putting them through my entire house I may have paid more attention to efficiency, but in the bathroom that's only used an hour a day it doesn't matter.

Not bad but the driver is built in to the unit so I wouldn't have chosen them.
They also don't say if they are dimmable or not, so I would assume not, which is a feature that I wanted.
It also doesn't say what brand of LED they have in them.

## timmmay

13237 posts

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CYaBro:
timmmay: I think it's these ones, but the Lighting Direct website seems to be down. It's these ones, in white. 11W, 600 lumen, 54 lumen per watt. I wasn't that bothered about absolute efficiency, they're nice looking lights that are bright enough and use less power than most others. If I was putting them through my entire house I may have paid more attention to efficiency, but in the bathroom that's only used an hour a day it doesn't matter.

Not bad but the driver is built in to the unit so I wouldn't have chosen them.
They also don't say if they are dimmable or not, so I would assume not, which is a feature that I wanted.

Not dimmable, apparently the dimmable model is out soon.

The driver's not inside the light, there's a cord between them. I doubt you can replace it if it breaks, but honestly at \$80 the lights are so cheap that if they fail after 5 years I just replace the whole unit.

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## CYaBro

2796 posts

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timmmay:
CYaBro:
timmmay: I think it's these ones, but the Lighting Direct website seems to be down. It's these ones, in white. 11W, 600 lumen, 54 lumen per watt. I wasn't that bothered about absolute efficiency, they're nice looking lights that are bright enough and use less power than most others. If I was putting them through my entire house I may have paid more attention to efficiency, but in the bathroom that's only used an hour a day it doesn't matter.

Not bad but the driver is built in to the unit so I wouldn't have chosen them.
They also don't say if they are dimmable or not, so I would assume not, which is a feature that I wanted.

Not dimmable, apparently the dimmable model is out soon.

The driver's not inside the light, there's a cord between them. I doubt you can replace it if it breaks, but honestly at \$80 the lights are so cheap that if they fail after 5 years I just replace the whole unit.
g

Bugger!  Your link is working now and the price is only \$67.90 at the moment. :D

## richms

20354 posts

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CYaBro:

Bugger!  Your link is working now and the price is only \$67.90 at the moment. :D

I can only find 3000k on lighting direct. At that price if they do 4000k or better then it becomes a no brainer to install them, so long as the beam spread is acceptable for in home use.

Richard rich.ms

1052 posts

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switchlighting, will the new EECA / Energy Star luminaire labelling standards address the inconsistancies with claimed light output and efficiencies. All I am aware of is the CFLs will now have to be labelled with light output (in lumens).

## timmmay

13237 posts

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richms:
CYaBro:

Bugger!  Your link is working now and the price is only \$67.90 at the moment. :D

I can only find 3000k on lighting direct. At that price if they do 4000k or better then it becomes a no brainer to install them, so long as the beam spread is acceptable for in home use.

I can't remember what I got, and they're not installed yet. From memory I got one that's neither a cool white nor a warm white, a nice balance.

It has a beam spread of around 90 degrees, with a translucent diffuser, so it's pretty good. I had one working in my hand, it's really pretty bright.

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## richms

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Ok, will be interesting to see how they go.

I am very happy with the 7w viribrights in normal downlights around the house so would only be considering these for the bath areas, would want the same colour as the rest of the house.

If the price approches the price of a viribright in a cheapish recessed E27 GLS fitting then I might opt for them in other places too, but really I think just kitchen and bathroom need the IP fittings.

Richard rich.ms

## CYaBro

2796 posts

Uber Geek

Lights arrived this morning.
Just wired one up temporarily on the workbench at work and almost blinded myself!
Not a good idea to be looking directly at the LED when you turn it on. :)

## timmmay

13237 posts

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I had the same experience with my LEDs, super bright... just like any light bulb really.

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## richms

20354 posts

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Ive just got my 10W bare LEDs on a heatsink from ebay that I am going to be putting in the aquarium, cant recall if I got the 10000k or 12000k now, but till my drivers arrive I cant really see how they go.

Richard rich.ms

## switchlighting

18 posts

Geek

Interesting question.... Only lights that pass the rigorous energy star testing will have to display any of the energy star required markings. I have had a quick look through the energy star tests and packaging but cannot find a requirement to mark with lumen output.... not sayings it not their though as the document is 40 pages long. I would imagine if it is energy star then it should be correct though.

Cheers.

## networkn

14884 posts

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Do you think it would be reasonable to use LED lighting in a kitchen?

http://www.houzz.com/photos/kitchen-lighting-and-cabinet-lighting/

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