sid Posted February 22, 2011 Share Posted February 22, 2011 My rudimentary knowledge of physics has let me down!Take a ceiling light fitting with a maximum allowable wattage of 60W; is a new engery saving bulb rated at 15W (but equivalent output 75W) too powerful for this fitting? I'm assuming that the marked maximum ratings are based on the heat produced by a normal incandescent bulb? The newer ones don't get as hot, do they?Also, and this is where my O level physics fails me, I don't understand how you can input 15W of power and get 75W of light out. Where's the other 60W come from? [blink]I'm sure someone will provide an explanation, but first and foremost I need the answer to the light fitting/bulb query, 'cos I'm doing that today!Sid Link to comment Share on other sites More sharing options...
andyh4 Posted February 22, 2011 Share Posted February 22, 2011 Sid 15W low energy bulb in a 60W fitting is just fine. The ratings for fittings is because conventional incandescent bulbs give out a lot of heat (that is the missing 60W and more) and this melts and degrades the fittings. Link to comment Share on other sites More sharing options...
JohnRoss Posted February 22, 2011 Share Posted February 22, 2011 An incandescent bulb outputs most of the energy as heat and not light, as much as 95%. The modern high efficiency bulbs output much more of the energy as light and not heat therefore you need fewer watts, the rate of doing work, than you do with incandescent bulbs to get the same amount of light. Having said that I don't like them in situations where you only want light for a short time, like loos, as they are slow to produce full light output taking several minutes to warm up......................JR Link to comment Share on other sites More sharing options...
sid Posted February 22, 2011 Author Share Posted February 22, 2011 Thanks guys!John, I agree about them being slow to warm up; not ideal for a stairway for example. They do seem to be getting better though; I've got a couple of the "folded fluorescent types" (Philips) which must be 10 years old now, and they take ages. Having said that, how many ordinary bulbs would last that long!Sid Link to comment Share on other sites More sharing options...
Quillan Posted February 22, 2011 Share Posted February 22, 2011 You know the old story about these bulbs. Apparently designed by a woman so that when you go for a pee they only become bright enough for you too see when you have already peed on your foot. [;-)] Actually I got some from Carrefour recently that get to full brightness within seconds unlike others I have bought in the past. Link to comment Share on other sites More sharing options...
Théière Posted February 22, 2011 Share Posted February 22, 2011 It's all to do with lumens per watt not watts consumed hence "equivalent too" in light output (allegedly) [geek]LED's have now passed CFL's in light output so the CFL's are history.........wonder if you'll stock pile those when the legislation forces change [;-)]Led's are also near instant to full brightness so no peeing anywhere but where you wanted to [:-))] Link to comment Share on other sites More sharing options...
PaulT Posted February 22, 2011 Share Posted February 22, 2011 About to put our UK house on the market so needed to obtain an Energy Performance Certificate. Thought 'I'll put in some low energy bulbs'. It is not the time that they take to come to full brightness it is the greeny light they give off.Got the certificate so the ordinary ones will go back in.Paul Link to comment Share on other sites More sharing options...
sid Posted February 22, 2011 Author Share Posted February 22, 2011 [quote user="Théière"] It's all to do with lumens per watt not watts consumed hence "equivalent too" in light output (allegedly) [geek]LED's have now passed CFL's in light output so the CFL's are history.........wonder if you'll stock pile those when the legislation forces change [;-)]Led's are also near instant to full brightness so no peeing anywhere but where you wanted to [:-))][/quote]I notice that there is a lumen figure quoted now; 799 for the ones I bought recently 15W (75W equivalent). Still quite expensive here and these were a box of 7 for 14€ at Leroy Merlin; I haven't seen any cheaper over here. I'm sure the LEDs will take over but I don't think I'll be running round the house replacing the existing bulbs until the prices come down or stocks of existing ones dry up completely. Link to comment Share on other sites More sharing options...
JohnRoss Posted February 22, 2011 Share Posted February 22, 2011 The new light emitting diodes are very bright and I bought a small LED type pocket torch, 4 AAA size cells, which was on offer at Lidl the other week. Much brighter than a conventional torch with a filament bulb. It gave a very bright white light but there was a warning not to shine in the face of animals or people as may damage the eyes and after using it for a time makes my eyes ache a bit even not looking directly at the beam. I would not want to sit in a room with this type of lighting!......................JR Link to comment Share on other sites More sharing options...
woolybanana Posted February 22, 2011 Share Posted February 22, 2011 Recent government research in France indicates that LED lights are definitely not safe to use close to for long periods and are particularly bad for children. It is the blue light that is the problem somehow. So, the uptake here might well be limited to non high use areas.And I do wonder if they would be safe for the doggies eyes! Link to comment Share on other sites More sharing options...
Quillan Posted February 22, 2011 Share Posted February 22, 2011 I seem to remember from years ago that you can't actually get white LED's. To get what appears to be 'white light' they 'cheat'. I agree with the torches, I bought one with just two LED's and its got about a 50M range, ideal for walking or finding the dogs at night.My biggest problem is we inherited out house with loads and loads of 'candle stick' type lights some of which have glass tubes over the lamps. The low energy bulbs don't fit and the other fittings that don't have glass covers need opaque lamps which they seem to have stopped selling recently. For up lighters I have been using either low energy or for dimming these tungsten or whatever they are called bulbs but at four to five Euros a pop they are just as expensive. Somebody told me Ikea do pretty good deals on bulk buys of low energy bulbs and that they are quite good although I have no first hand knowledge. Link to comment Share on other sites More sharing options...
Babbles Posted February 22, 2011 Share Posted February 22, 2011 We have quite a few vintage chandeliers where the bulb is visible and you can now get LED that look like the original twisted tip bulb. I was panicking that our supply of incandescent ones had run out and I'd have to use ugly bulbs, not sure how long they'll last but at least they are more energy efficient and we can keep our vintage lighting, I found Leroy Merlin to be the cheapest (surprisingly!) Link to comment Share on other sites More sharing options...
Bob T Posted February 22, 2011 Share Posted February 22, 2011 LEDs last much linger than any other bulbs. I have two 3 watt spotlight LEDs above my desk and they have a bright white beam. I am slowly changing most of the bulbs in the house to LEDs, but buying them on ebay as they are much cheaper. A 50 watt halogen GU10 can be replaced with a 3 watt LED and for less than a tenth of the power puts out just as much light. Link to comment Share on other sites More sharing options...
just john Posted February 22, 2011 Share Posted February 22, 2011 I've just bought a set of shower down lights for a bathroom which are to the new regs, IP65, GU10 with a 21 LED but warm white. They claim to only use 1.8 watts of energy with a life expectancy of 50000 hours and suitable for zones1 2 & 3. We'll see. Link to comment Share on other sites More sharing options...
Théière Posted February 22, 2011 Share Posted February 22, 2011 The coldness you speak of is usually due to the light wave length or put succinctly the Kelvin factor. 3000-3500 is warm light (yellow end of the spectrum) and 6000-6500 is cold light (blue end of the spectrum) So be sure to specify when ordering. The Kelvin factor does not relate to light output although the blue end seems brighter (lumen's are the measure of brightness) SMD (surface mounted diodes) are more powerful than the normal single LED's that you see clustered together, the current series to look out for is the 5050 SMD lamps as these are very bright. Link to comment Share on other sites More sharing options...
sid Posted February 22, 2011 Author Share Posted February 22, 2011 Now that we've drifted onto LEDs I'll mention that I have an LED head-torch which I've found absolutely brilliant (pun intended) for working in dark corners or when the electricity is off while I'm rewiring. Also handy for walking at night especially here where it is really dark!! Naturally the light shines wherever you happen to be looking! Link to comment Share on other sites More sharing options...
Théière Posted February 22, 2011 Share Posted February 22, 2011 Me too, one of them clips to the peak of my cap if that's what I am wearing, low profile so you don't look like a miner [:)] Link to comment Share on other sites More sharing options...
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