Ref Part L2 (B) Lumens per watt when only Candelas stated!

[toplightco]

Most reflector type lamps do not state their output in Lumens but in Candelas. Clearly the two cannot be converted, so how does one calculate the Lumens per Watt thing?!

 

[wallyanker]

Hi,
Not sure about lumens to watts but I can tell you the calculation for lux levels on a work surface for eg.

Formula: E(lux) = I(candela) / d(distance)squared


So, if you have a lamp of 3000 candela 3 metres above a work bench, the lux level on the bench would be

3000 / 3squared = 333.33 lux

Hope this helps

 

[acat]

How to Calculate Lumens Per Watt | eHow.com

Hope that link solves the problem for you


Chris