Lumens - Effective Lumens - RAW Lumens LED rating?

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It would seem we have Lumens and also Effective Lumens often stated as higher figure and RAW Lumens which is also higher measured before light reduction through glass and per LED x number rather then output as built.

Look at a MR16 spot lamp and typical 100 lumen per watt to 50 lumen per watt and automotive lamps have to be measured after they have warmed up but other lamps can be measured on switch on which will give higher output.

It would seem therefore as far as LED lamps go the lumen means very little so if lumen does not tell use real light output and watts don't tell us real light output how can we select lamps?
 
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A real can of worms.

Does one measure the lumens from the LED when it is carrying it normal operating current. or does one measure the lumens emitted when the LED is carrying a pulse of current several times its normal current. Pulsing an LED with higher than normal current is a way to obtain a brighter light than the LED would otherwise give.
 
I did try pulsing myself and the results did not go as expected however I never considered the accuracy of the lux meter when reading pulsed light. Reduced the lumen by 1/3 in my living room but lights are brighter as to if CFL was over rated or LED under rated can't tell. But lumen is clearly not doing what was intended. 10 LED bulbs in living room 8 x 250 lumen and 2 x 100 lumen looking at bulbs can't say which are which.
 
I have been investigating LED lamps and have a sort-of rule of thumb which is a reasonable guide.

We can all reasonably estimate the light output from tungsten lamps.

1W LED == 10W tungsten.

So if you need the equivalent of a 60W lamp, you will need a 6W LED lamp.

This seems to be more power than the LED manufacturers might lead us to believe but has been born-out by my own disappointment with previous LED lamp purchases.
Frank
 
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My main living room started with 2 x 100W now 27W LED so yes seems about right. Mothers wet room want 150W now 6W in this case does not work out. Both cases light now is ample.

10W was smallest GU10 tungsten I could find and was over kill with bed side lights so swapped for 0.58W which was failure so swapped again to 2W which is like the 10W brighter than required.

But camera is another thing at f3.5 to get 1/30 second need ISO(ASA) setting at 1600 in old days I used 600 ASA film in doors without a problem getting fast enough shutter speed to hand hold without flash.
 
I have been investigating LED lamps and have a sort-of rule of thumb which is a reasonable guide.

We can all reasonably estimate the light output from tungsten lamps.

1W LED == 10W tungsten.

So if you need the equivalent of a 60W lamp, you will need a 6W LED lamp.

This seems to be more power than the LED manufacturers might lead us to believe but has been born-out by my own disappointment with previous LED lamp purchases.
Frank

my equation is very similar at 1=9w 10=90w to not be disappointed
of course there is no one answer


i have recently measured all my led bulbs and the rated wattage varies so much i have 4w leds using 4.4w input and others rated at 4w with similar outputs using 1.7 or 2.2w

i also checked some compact fluroes today and some where around 20-30% over rated value with a phillips 8w =9.5-10.5w but with a similar light output to the just mentioned 1.7 or 4.4w leds
then an 11w on 12-13w giving a good possibly 60w or 7w led bulb

should also mention all my low energy bulbs are at least 5 years old as i have been buying only leds for at least 5 years so most le bulbs are unused

will also say all measurements where with the same plug in meter so inaccuracies will be the same over all bulbs
 
You make a good point. I did check current on first batch of CFL I got as I had problems with florescent tubes. At Sizewell decided to use 60W 110V florescent lamps for some tunnels assuming approx 0.5A each should get 32 on a 16A plug so not wanting to get too near to the edge put 25 lamps on a string. After they tripped about 5 times we realised something wrong so clamp on ammeter and drawing 20 amp clearly a problem when on 16A MCB.

I took a lamp in the workshop and tested it and found drawing 0.9A instead of 0.55A expected. As they were 110 there was a 110 volt and 128 volt tapping on the auto transformer so moved to 128 volt and current dropped to 0.6A with no real drop in light output. So moved tapping and tested last few in string would not light so returned last 5 to 110 volt tapping total then at 15 amp so all running A1 after that.

When years latter I measured a HF florescent I realised that these much better adjusted to low or high voltage and had far less problems so was not sure with CFL if HF or induction controlled so tested. Result as label said.

I note with LED lamps low voltage the range of voltage is huge often 85 - 260 volt clearly some electronic control within the lamp likely some switch mode unit.

This likely means the LED also gets pulses which then means we have a measurement problem. Get a light meter and the question is damping methods used to give a steady reading? It may give peak or average light so can give a completely erroneous reading if LED's are switching on and off. I would guess OK at 100Hz and above as that would be standard with florescent lamp but same applies measuring the amps. Also with amps any switch mode power supply could cause peaks which can upset meters.

To measure 5 amps with either my clamp on or plug in meter I would say reasonable accurate but to measure 0.013 amps (3W) is really just too small of a current for these to measure. I note on stand-by my free to air satellite box measures as using nothing even when set to auto record must be using some current just too small for the meter to measure.

So to measure would mean using something like my AVO Mk8.

Lamp life is a problem also. Most LED lamps have more than 1 LED and as the LED's fail the lamp will get dimmer so when quoting 10,000 hours is this point where 50% of 100 lamps will have failed completely or is it when 50% of the LED's within the bulb fail or when the light output from 100 bulbs is reduced to 50%?

It just seems with both CFL and LED lamps there is a complete lack of standards! I was considering using LED lamps in the caravan used may be 5 weeks a year and light on may be 2 hours a day so 10,000 hours = 142 years don't think I will be returning any! Even with the house 5 hours a day with lights on equals five and a half years can you see Lidi taking back bulbs even 2 years old? Oh dear lost my receipt.
 
You make a good point. I did check current on first batch of CFL ~~snip~~I took a lamp in the workshop and tested it and found drawing 0.9A instead of 0.55A expected.
One of my projects was measuring the current on the feed to lights in pedestrian underpasses with the aim of detecting when a lamp failed or was vandalised. One feed to groups of between 10 to 20 lamps.

The results were logged and in cases of vandalism would be used with CCTV to identify the culprits. ( No CCTV in the underpasses so people walking to and from at the time were prime suspects ).

Due to the variations of current during normal operation the results were not as good as hoped for. Current changes due to vandalism were also very variable. A fitting with smashed tubes could take more current than before the vandalism.
 
Yes I have been surprised but think Vandalism is rather raciest the Vandals did a lot of good too. ;)

I do remember driving into a car park and watching the snow like effect in mirror then realised it was my aerial smashing the florescent tubes. Stopped removed mag mount and hid it then carried on and parked.

Remember a client taking time lapse photos and saying our cranes were not working and I had to fit data loggers to show they were.

But as to bulbs back in 1960 a bulb was cheap and although they may have not lasted as long as they should have no one was that bothered when one failed.

Today however a LED bulb costs a fair bit of money so we want to select correct size first time and for them to last as it says on the packet.

Using 10 bulbs in my living room when one fails at £3 each not a big issue but with 2 bulbs at £15 each then one is more worried about bulbs failing prematurely. This idea of bulb life being how long it takes for 50% of the bulbs to fail may have been valid for tungsten bulbs but is hardly valid for florescent and LED where unlike the tungsten they get dimmer with age so need changing before they actually fail.

I have gone into a dimly lit warehouse and changed the tubes and after needed sun glasses the point is it takes so long for the light output to fall off we don't realise how dark the area has become.

My son at work uses a meter to measure the light and has had complaints that new LED lights were too dim yet the meter showed they were same as florescent they replaced. He had to move the LED lights to corridors and return to discharge in the factory floor.

He has noted when reading the spec there is no comfortably between makes some state hours until 80% of original light output some state hours to 40% of original light output.

So in maybe a years time I may have to get a full set of lamps for living room and then use the lamps from living room in dinning room where not as much light is required.

This idea of moving lamps means we want to use many small bulbs all same type rather than one bulb per room. It means a re-think on where to position ceiling roses and although with new build easy enough to adapt adding ceiling roses is not what most people want to do.
 
I have been investigating LED lamps and have a sort-of rule of thumb which is a reasonable guide.

We can all reasonably estimate the light output from tungsten lamps.

1W LED == 10W tungsten.

So if you need the equivalent of a 60W lamp, you will need a 6W LED lamp.

This seems to be more power than the LED manufacturers might lead us to believe but has been born-out by my own disappointment with previous LED lamp purchases.
Frank

my equation is very similar at 1=9w 10=90w to not be disappointed
of course there is no one answer


i have recently measured all my led bulbs and the rated wattage varies so much i have 4w leds using 4.4w input and others rated at 4w with similar outputs using 1.7 or 2.2w

i also checked some compact fluroes today and some where around 20-30% over rated value with a phillips 8w =9.5-10.5w but with a similar light output to the just mentioned 1.7 or 4.4w leds
then an 11w on 12-13w giving a good possibly 60w or 7w led bulb

should also mention all my low energy bulbs are at least 5 years old as i have been buying only leds for at least 5 years so most le bulbs are unused

will also say all measurements where with the same plug in meter so inaccuracies will be the same over all bulbs


But are you actually measuring real power (Watts) or apparent power (VA ... volts x amps)?

The units I have played with have a terrible power factor so volts x amps would be way off.
 
i didnt check for any voltage fluctuations
but they where all meassured from the same socket with nothing in the house drawing any real amperage possibly 1kw total max

i checked some previously monitored bulbs on each occasion and none gave a different reading[the wattage penciled in on the bulb body along with date off use]
 
Ok...... so you measure current and assume volts?

I'm sorry to say that just wont work.

To get the real power (watts) you need to multiply the actual voltage by the in-phase component of the current.

Simply multiplying volts x amps gives you apparent power, otherwise known as VA, this is NOT the same as Watts.

The relationship is Watts = VA * power factor. The power factor for these lamps is really poor 0.6 to 0.8 at best.
 

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