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Light-bulb labelling.

Community Veteran
Posts: 2,280
Thanks: 218
Fixes: 1
Registered: 04-08-2009

Light-bulb labelling.

I suppose everyone now knows about the demise of certain light bulbs, but one snippet I wasn't aware of is that from 1st. September, the Eco-design Directive for Energy-using Products (EuP) means that lighting must labelled in terms of lumens, instead of electrical watts. The old 100w bulb had an output of around 1300 lumen...  useful chart shown below.
34 REPLIES
alanf
Aspiring Pro
Posts: 1,931
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Registered: 17-10-2007

Re: Light-bulb labelling.

That's a surprise. LED less efficient than compact fluorescent? I thought LED was going to replace CFL when the price and colour balance was right.
Community Veteran
Posts: 2,280
Thanks: 218
Fixes: 1
Registered: 04-08-2009

Re: Light-bulb labelling.

I think the problem with LEDs at the current stage of evolution is the control gear in the base of the bulb, which isn't as clever as it could be. Give it another 18 months and it will probably change. Compact fluorescents were a bit like this when they first appeared (in jam-jar format).
Community Veteran
Posts: 6,735
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Registered: 02-02-2008

Re: Light-bulb labelling.

I discovered a neat design of compact fluorescent recently called GX53.
It's a sort of flat disc, designed for example for downlighting in fitted firniture, but can be used in many places.
I think they go up to about 13W (as bright as an old 60W bulb)
magnetism2772
Grafter
Posts: 983
Registered: 06-06-2010

Re: Light-bulb labelling.

why?
when the unit of light is the candela
Community Veteran
Posts: 6,735
Thanks: 12
Registered: 02-02-2008

Re: Light-bulb labelling.

Nope.
Lumens is the "amount" of light emitted, candela is the intensity per unit area falling on a surface (roughly).
magnetism2772
Grafter
Posts: 983
Registered: 06-06-2010

Re: Light-bulb labelling.

a lumen is defined as one candela multiplied by one steradian
magnetism2772
Grafter
Posts: 983
Registered: 06-06-2010

Re: Light-bulb labelling.

oh  yes
and  light is radiated
magnetism2772
Grafter
Posts: 983
Registered: 06-06-2010

Re: Light-bulb labelling.

for the most technical
A candela is a measurement of the intensity of light- ie how much light
A lumen is a unit of standard measurement used to describe how much light
is contained in a certain area
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Light-bulb labelling.

well i never
Community Veteran
Posts: 2,280
Thanks: 218
Fixes: 1
Registered: 04-08-2009

Re: Light-bulb labelling.

Come on Pierre, you MUST have!!!!    Cool
magnetism2772
Grafter
Posts: 983
Registered: 06-06-2010

Re: Light-bulb labelling.

the differential equation is saying
a  lumen is the ratio of a small change in a magnetic flux  to a corresponding small change in time
thus the lumen unit is looking at  illumination in more modern terms to include  power (which is the watt per sec)
magnetism2772
Grafter
Posts: 983
Registered: 06-06-2010

Re: Light-bulb labelling.

the candela appears  just as a pure unit of  luminous flow ( to something)
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Light-bulb labelling.

why dont you learn to use joined up writing threads
magnetism2772
Grafter
Posts: 983
Registered: 06-06-2010

Re: Light-bulb labelling.

thanks for your contribution peirre
Do you think what i've said is correct ?