Bulbs, wattage, heat and maximum ratings

[Bert Coules]

I need wall lights with individual switches for the bungalow I'm doing up. Wickes have these:

use SES globe bulbs and carry the message "maximum wattage 40W" but just how critical is that warning? Is it a question of heat output? Wickes stock low-energy bulbs marked as equivalent to 35W and others rated as equal to 50W: is there really so much difference between the two that using the higher-rated ones could actually be dangerous?

It's not clear from the photo of the unit but the curved glass shade is open top and bottom and also stands clear of the wall on either vertical edge. The bulb itself is not enclosed and I would have thought that there's a good deal of air circulation around it.

Many thanks.

[Dave Liquorice]

Reasonably, the plastics will fail a lot quicker if overheated or any glass crack.

The "maximum wattage 40W" refers to power input, so a 40W incandescent bulb or a 40W rated, not equivalent, CFL. The largest commonly available CFL's are about 20W input.

Your biggest problem might be finding a low energy bulb that fits the space and still looks OK. I suspect that by "SES globe" you mean something the size of a golf ball not a base ball.

[Dave Plowman (News)]

Unless it says otherwise, I'd take the rating to refer to the actual power consumption of the lamp - not the equivalent rating of a CFL.

[meow2222]

Find one that uses BC bulbs, then you can pt any type in in future

[Bert Coules]

Thanks for that. It doesn't say otherwise.

This is a really naive question, but am I right in thinking that when the CFL spec gives an equivalent rating it relates to light output? So, for example, a bulb labeled "11W (60W)" will give a significantly brighter light than one that's "8W (40W)"?

If so, and assuming that you're right, I could quite safely use an 11W CFL.

[Bert Coules]

Thanks for that. You're right about the size: mini-globe is the spec. The highest-rated CFL I've found that will physically fit that particular unit is 11W (60W): above that, the size starts being an issue. But a light output equivalent to a 60W incandescent (assuming that I'm right in thinking that's what the figures indicate) is considerably better than I thought I could safely get.

Ah, it's not clear from the photo but the curved glass shield is frosted: the bulb can't be seen when not turned on, and I think that its shape will only be vaguely discernable when lit.

[meow2222]

11w is 40w, not 60. The packs compare to soft filament lamps, not GLS

[meow2222]

And its when new, or at 200hrs IIRC. CFLs lose output much more than filament, so now you're down to 30w or so equivalent, once they're no longer new.

NT

[Bert Coules]

Thanks. I was going by this site

where the 11W bulbs are clearly listed as 11W (60W).

[harry]

You shouldn't exceed the maximum wattage on any account. There's a good chance of starting a fire. At best bulb life would be reduced.

CFLs are not the answer as they are more easily damaged by overheating. (ie damaged at lower temperatures)

[Dave Liquorice]

The only really naive question is the one that isn't asked.

Ish. Equivalent light output of a incandescant bulb, that may or may not be clear/pearl... Pearl knocks about 10% off the light output.

It will give out more light yes but 11W(60W) is a tad optomestic IMHO. CFLS use about 1/4 the power for the same light output so a 60W equivalent CFL should consume aroud 15W.

The only real way to comapre light sources is to compare the lumens but don't fret about the odd 10 or so. Packaging these days should have the lumens on.

[GMM]

I would interpret that as requiring the globe bulb because it's small than some others so will be concealed within the fitting and the wattage as the potential to overheat the thing. Mind you, it would probably look a bit weird with 40W of CFL light! (If such were even possible)

[Dave Plowman (News)]

The first part - 11W or 8W - is the part you need to know for safety in your fitting. The second part (60W) or (40W) is the so called equivalent light output, which is a bit misleading. As it is usually quite a bit less than a normal lamp of that size.

Yes. You could safely use any CFL up to 40w - assuming you can find one which will fit.

[Mike Tomlinson]

En el artículo , Bert Coules escribió:

It'll also make the light more pleasant - I have a couple of CFLs (which I can't stand normally) behind frosted glass and they look fine.

[Bert Coules]

With apologies for the blanket response, many thanks to everyone for the latest replies. I now have a much clearer idea of the situation.

[Man at B&Q]

That's what they want you to think. In practice 4x is a more reasonable multiplier from actual to equivalent.

MBQ

[chris French]

Yeah, well, they are way optimistic with those comparable wattage figures. 4xCFL wattage is a better guide

[Arfa Daily]

1 x half-burnt match per watt is even better ... :-)

Arfa

[Arfa Daily]

Are you sure ... ? d;-)

Arfa

[Graham.]

Yes, ban all CFLs forthwith, and bring back gas Mantles.