Hi, I've just fitted a 4x50w light fitting in the kitchen that uses GU10 50w bulbs. My wife thinks it's too bright so I was going to replace the bulbs with 35w ones, however in the instructions it says to only use GU10 50w bulbs. Is this correct ? Are these fittings designed for a specific watatge of bulb or can I just replace the 50w oens with 35w ? If I can't replace I suppose I'll have to fit a dimmer.
On Sat, 27 Nov 2004 21:27:34 +0000, Bill Scarab strung together this:
That would be a maximum rating, rather than a fixed rating. 35W will be fine.
I'd do that anyway, at least you can make it brighter if you want to. I alays overspec lighting slightly and add a dimmer so that there is always the option of extreme illumination if required!
I suspect what it means is don't use GZ10 lamps, which being dichroic, will overheat the fitting. In theory, they shouldn't fit in the lampholder, but you never know. A 35W GU10 will be fine, and is much more efficient than dimming.
Thanks for the quick reply, I hoped that was the case but never having used these lights before I wanted to check. The main reason for not using a dimmer is that currently theres a security time switch fitted so if i fit a dimmer I'd have to lose that. Thanks again. regards Bill
And what ever you use the feckin bulbs will blow after 100 hours of use no matter what brand you use or whether you use a dimmer as a slow start or not.
so I am not the only one finding this! Put some lights up a few weeks ago with 50W GU10s in and have had 2 bulbs go already. Are there LED alternatives for this brightness yet? (I have seen some LED GU10s but havent really looked close to see how bright they are - wouldnt imagine they were that bright yet)
LED is roughly the same efficiency as halogens. I think the LED ones are all under 10W, so it would be like putting in a 10W halogen. LED lamps are usually much narrower beam and can appear quite bright centre beam, but that's all there is.
The local branch of 'SETS' - which is a distinctly trade-scruffy counter style outlet, has a range of illuminators set into the 'customer-area' ceiling. On request they'll switch them on/off individually and let you compare the different lamps. [I was considering utilising a GU10 40W white LED assembly which I was able to 'see' as opposed to reading in the catalogue. It wasn't quite 'designer decor' setting, but it enabled me to see the lamps illuminated. ] _I_ decided not to go the 40W LED (GU10) route - but your mileage may vary.
Are you sure it was 40W, rather than some waffle words like
40W equivalent light intensity centre beam? I doubt a lamp the size of a GU10 can operate at 40W and still be below the temperature at which LEDs would be destroyed.
You are correct: a re-read of the catalogue confirms GU10 (envelope fitting) direct replacement does not require transformer - light output 20W equivalent
1.8W power consumption; fifteen LED set into GU10 envelope available red. blue, orange, green and blue-white (IMHO that should read very-blue/white) Sorry for the confusion.
What that actually means is light output equivalent to a 1.8W lamp (since halogens and LED's are pretty near each other in efficiency). However, the 4" diameter spot of light it creates on the floor under it might be as bright as if you had a 20W lamp, although a 20W lamp would manage to light a much bigger area to that intensity.
So at this point, I would suggest LED GU10's are about as much use as a chocolate teapot (actually, a chocolate teapot is probably more useful, as you could at least eat it).
You can get 7W compact fluorescent GU10's. They probably have the light output equivalent of 25W, but are wide angle.
) about GU10 as I am in the process of looking at my hall and landing lights. I have some new GU10 units that were supplied with 50w lamps.
One of the things I would like to do if have a child friendly dim light on overnight so that has to be energy efficient. I decided to look at the GU10 LED and CF lamps as well. I am testing them by putting them in a bare fitting on the end of a piece of wood and seeing if they give enough light. In the 'light' (sorry) of the discussion about strength I thought I'd experiment. I don't have a light meter but I do have a photo-voltaic cell based battery trickle charger for the car. The other choice, a Meccano LDR from the 70s only gave point readings and wasn't reproducible. To test the lights I measured the output voltage. I won't bore you with the sizes/distances but they are available. These tests did prove repeatable.
The LED and CF lamps I tested were from QVS - slightly cheaper than TLC in this case but stock not so good. See
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. The TLC catalogue rates the LED as 20w equivalent.
A few observations from my tests with the bulbs about 2.5m from the charger::
(a) 50w B&Q lamps supplied with light fitting gave 6.8v, a softer yellower light than my LV downlighters. (b) 35w 40 degree gave 5.5v and a similar spread of light. (c) 50w 25 degree gave 8.3v and a narrower spread.
The LED gave a narrow beam, that is quite blue still. It didn't produce any power (had to be less than a metre from the PV array to do that but this may be the frequency).
The CF again didn't score anything and is slightly uglier. Wider angle but slightly less bright than the 35w. Took a while to get to maximum brightness.
In conclusion:
I think I will end up using the LEDs in front of the bathroom and over the stairs as child lights. The bulb will be awkward to change as it is
3m from the half-landing. The 35w ones will end up on the landing (which has a security timer on it). Downstairs my long hall will have a mix of the CF lights and 35w on the six-way unit and maybe another CF light at the bottom of the stairs.
If anyone can think of a solution to this
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, about wireless switches as they need to switch these lights, posted a few days ago I'd be grateful as I don't want to chase holes.
If anyone has any other ideas about tests you'd like on these bulbs let me know.
For 'child' (and elderly) friendly dim lights for the hall, I've settled on plug-in photo-voltaic switched lamps. They're available in packs of one/two/three etc in the sheds remarkably cheaply. They seem to utilise 7W candle filament bulbs. I assume you've got at least one 13A three-pin outlet that you can plug into? At 7W only, I'm not really too concerned about efficiency! Using these devices saves all the bother of switching, chasing cables etc and if Two-jags bothers to chastise me for the prolific consumtion I'll ask him how many Joules are locked into the manufacture of cables, switches and fittings for any other solution.
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