LED bulbs lumen and watts.

[ericmark]

Large room had single lamp in centre which at 12.5 watt LED did not really cut it, so been looking for a light fitting to take multiple bulbs to increase output, found a fitting with 8 E14 bulbs so fitted that, leaving just buying the largest E14 (SES) bulb I could find. Wife picked up 2 at 5.5W 470 lumen at £2.20 plus vat. My existing stock were 2W in the main.

So into HomeBargains and picked up 8 x 6W bulbs around £2.29 each, rated 470 lumen then noticed the 5W bulb at around £1.29 also rated at 470 lumen. So swapped the bulbs in the basket. Both bulbs were same make.

So why three bulbs all 470 lumen with 3 different wattage ratings? And higher the wattage or the less energy efficient the more they cost. With such a low wattage can't really measure with plug in energy meter, and £10.32 for 3760 lumen is good valve.

But why do same make of bulb vary so much in price from same shop.

 

[333rocky333]

was some dimmable. that may affect the cost

 

[SFK]

Why "the higher the watage .... the more they cost (when the have same luminance rating".

I always saw this because many people only look at the wattage and do not understand lm, and so base their purchase decision on higher wattage is more light and should cost more. Seller knows this and so reflects this in price.

Sfk

 

[ericmark]

I think you are both correct, the dimmer-able bulb in general uses a simple capacitor as current limiter which is not as efficient as a pulse width modulated current limiter so one would expect the non dimmer-able costing a little more, but this is the reverse.