Rating of "low energy" bulbs versus the lamp shade

[Fleabag]

I bought a lamp shade for use on a ceiling pendant. The label on the wrapping for the lamp shade stated it is rated at 60W for a conventional incandescent light bulb, or 11W for a low energy "60W equivalent".

The room is a little on the large side for a single pendant but up until now I have used a 100W bulb in a suitable shade and its been light enough.

I know that low energy bulbs can still run pretty hot, but my question is why can I only use an 11W low energy bulb in this shade? I would really like to use a 20W low energy bulb as this would be bright enought. Naively, and subjectively, I would have thought that these low energy bulbs would be bright but cooler than the incandescent and therefore not as much of a fire risk?

Thanks in advance for any explanations offered

Fleabag.

 

[ericmark]

We are obliged to follow manufactures recommendations I would agree it seems odd but maybe there is something we are unaware of.

 

[davelx]

If the lamp is rated for a bulb that dissipates energy at a rate of 60W I can conceive of not reason that you cannot use one that only dissipates 20W! It's the heating effect we are concerned with and 20W is only 1/3 of 60W for the greater light output,

The 11W=60W is only a way of showing the efficiency and comparing the light output.

I suspect that the manufacturer just hasn't thought about it and is taking the easy option, and probably knows SFA about basic physics/thermodynamics

 

[big-all]

as an aside do not belive the manufacturers claims if you expect the low energy bulbs to be 5 to 5.5 times there value you will be dissapointed go for 4 times then they wont be too dim

so an 11w would = 44w

and a 20w would = 80w

as for the heat issue it is less but more concentrated and in the plastic base

if the shade is like an upturned bowl without any gaps the i would be carefull off exceding the limits
if there is some gaps to let the air flow then i would say up to 50% more would be equivilent to a 60w bulb so 16w would be the maximum
if theres a decent gap then i would definatly risk 20w but check every 15 mins for the first hour then 2x30 mins in the next hour

 

[Steve]

Just FYI, I have a 20 watt lamp in my landing pendant with a shade rated for 60w. When its been running for several hours, I can wrap my hand around the lamp, still on, with no ill effect.

They run "very warm", not hot.