Technical question

[sally_maria]

For them that knows about electricity etc. ;-)

For quite a few years now, a lot of British lightshades have had warnings on them that they shouldn't be used with bulbs more powerful than 60 watts. This made perfect sense - bulbs get hot, and you don't want a too hot bulb in an enclosed space.

What's baffling us is that new lightshades have transferred that to the new low-energy light bulbs - so a shade that can only take a 60 watt normal bulb, can apparently only cope with an 11 watt low-energy bulb. How does that makes sense? Surely the point is that an 11 watt low-energy bulb puts out the same amount of light as a 60 watt traditional one, while using less energy, i.e. not wasting it as heat. So why can lightshade that can cope with 60 watts not cope with 17?

Or had we completely misunderstood what the issue was, and there's some very good reason why we can only use very dull bulbs?

Comments

[alitalf]

That may be incorrect. There is a theory that an 11W low consumption lamp gives the same amount of light as a 60W one (though I have yet to see one that does) so the shade must only be able to cope with that much light.

Actually, it is the heat that would be the problem. If you put a 100W lamp into a shade really only suitable for 60W, then the heat could cause damage. Maybe the shade would discolour much faster than otherwise.

The 11W lamp would not get nearly as hot, but even lower temperatures can damage the electronics in low consumption lamps, so they need to be kept significantly cooler than ordinary filament lamps. It would be true to say that if the shade traps heat close to the lamp, then you need to use a lower power because the temperature of low consumption lamps needs to be kept relatively low.

[sally_maria]

Thank you very much for this - that does make sense, and we'll bear that in mind. :-)