I have seen a light fitting that I like - it has 7 x 12 volt 10watt bulbs.
Can anyone give me an idea how this would compare with typical mains bulbs. Currently I have fitting with 3 x 60watt Halogena bulbs and don't want anything less in brightness.
3 x 60= 180W
The new fitting will not be as bright.
It's 70 Watts compared with 180 Watts, what do YOU think?
It's not quite that simple. LV produces *a lot* more light than GLS types.
In message , "Dave Plowman (News)" writes
That's true, but I still don't think the fitting the OP mentioned, (7x12V/10W capsule bulbs) is going to match the output of the existing fitting though.
Not sure I'd want to faff about with those bulbs in such a light fitting either, though their use does enable some nice interesting lights.
On the face of it, you've got 70 watts rather than 180 - so it should be a lot less bright.
However, the filaments in 12v bulbs are short and fat compared with long and thin ones in mains bulbs. This means that they can be run much hotter. A higher colour temperature means that much more of the electrical energy is converted to *visible* light rather than heat. [Compare the brightness of a
60 watt car headlamp bulb with that of a domestic (mains) 60 watt bulb].My guess is that the 12v lamps will give less light than the current fitting - but far more than the 39% suggested by the input power ratio.
But 60/240 = 0.4 Amp 10/12 = nearly an Amp.
It is the relationship between mains voltage and low voltage that is causing me some confusion. A web site (Next) gives this:
"Requires 10 x 12v 10w G4 halogen bulbs (included). Halogen is an efficient source of light using small compact bulbs. It provides a bright, clear light and is ideal for reading and working. A 20 watt halogen bulb provides approximately the same amount of light as a regular 60 watt bulb and lasts approx. twice as long."
What do I believe before spending my beer tokens. The small size of the 12v filament gives the impression of higher brightness.
Yes for the same wattage lamps.
Efficiency drops off for the lower wattage ones, so I would not expect any more pro rata, indeed I wouldn't be surprised if it was less. I have a 10 x 10W LV lamp, and the output is less than a 100W GLS, whereas if I fitted 1 x 100W LV instead, it would be significantly higher than the light output of the GLS.
Well put it this way, regardless of how much light the bulb actually produces, the overall light level of the room will be lower with a 20w halogen bulb than with a 60w gls bulb. They do look nice though :)
Alex
Whilst the light output might be correct, the life thing is wrong - in my experience. Certainly with GEC or Ring makes commonly found.
Not necessarily so. LV bulbs have internal reflectors, so direct the light were needed. Of course with white everything, the difference will not be so marked.
I understand your point Dave, but, and of course this is just my experience - my bathroom is currently just painted white all over (aside from floor) as I have yet to tear it all down. It used to be lit by two 60w bulbs, which I replaced with 3 x 20w halogen downlights that I was given. The room 'feels' much darker when you enter it now (unless you turn on the whopping great flourscent above the mirror left by the previous owners, in which case you blind yourself).
Alex
The type I am considering do NOT have reflectors - they are G4 (12v) or G9 (240v) Capsule bulbs.
How much do replacement bulbs cost?
Alex
It's not. Halogen bulbs produce a few percent more than ordinary bulbs, as they are run hotter, and hence are more efficient. LV halogens produce a few percent more than mains ones, but this all adds up to well under 50% more.
20W producing as much as a 60W bulb? That'd be what's known in the lighting trade as a pork pie.In message , Alex writes
20xG4 for GBP8 from screwfix, but i've seen them for over 2 quid a shot.
My guess lines up with yours; the use of capsule bulbs suggests that there won't be quite the fierce directionality of 12V spotlights bulbs discussed in The Other Bathroom Lighting Thread this week.
However, there is another downside of using 7 10W bulbs: they will need changing no less, and probably more, often than the 3X60W mains bulbs. Even though each bulb might have twice the life of a mains bulb (and I'm not sure if the little capsule bulbs have the same longer-life advantage as 12V spots have), there are just over twice as many of them - so On Average you'll be changing the damn bulbettes just often, ass-U-ming your "must fit a new bulb" threshold kicks in as soon as one blows...
Stefek
Too much - they will either fall in price or become obsolete I guess.
now youre introducing yet another factor, the inefficinecy of downlighters. Due to the way the light is directed, downlighters are normally much less efficient than uplights and trad wall lights.
Re the original question, LV halogens typically produce about 2x the light per watt compared to GLS, so 70w of LV halogen would be equiv to about 140w of GLS. The 10 watters may be a bit less efficient than 50 watt LVs, so it may translate to less than that, so really for identical ligth level you'd want that fitting plus a smaller 2nd light source - which is usually easily arranged. The bathroom cabinet / mirror is a very practical place to put a little extra lower power lighting. So is a low power uplighter.
NT
Unless you're talking CFLs, in which case it is pessimistic. Halogens look very nice and give a pleasant highlighting effect, but I can't help seeing the blood of Bangladeshi children dripping from the bulb. The guilt outweighs the quality of light.
Christian.
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