Clever idea needed (electrical stuff)

[mr messy]

Don't forget the lifespan of light emitters in any equation.....

 

[Custom24]

[QUOTE 2985792, member: 9609"]I would just wire it into the ceiling rose.

Haven't bought the LEDs yet, just trying to work out if it's worth it. At present in the kitchen, we have two mini tracks both supporting 4 x 50w mains halogen, that's a whopping 400watts (bloody ridiculous) - Personally I would take the things down and put up a couple of florescent tubes, but the wife likes these horribly glary halogin things. Anyway I have sourced some very good 7.5w LEDs that really do replace the 50w halogens, but they are a whopping £19 each.

So before I splash out £150 on bulbs I want to know a pay back time! And considering that for 9 months of the year the 400w of heat energy produced by the halogens supplements the gas central heating, and the other 3 months they are not on much as it's summer, payback is likely to be decades!

However first things first, I want to know how many hours per week they are on.[/QUOTE]
Yes, I thought it might be the ceiling rose, hence the "bang" comments by some others.

£19 for a LED is a bit much. For example, check out http://www.robertdyas.co.uk/lighting/light-bulbs/led/led-gu10. You can probably do better than that too. Also, you may find you don't need that much light. I was also using 50W halogens and I think I replaced them with 35W equivalents and didn't notice any difference. I'll have a look tonight to see what I have.

 

[mr messy]

[QUOTE 2985809, member: 9609"]Indeed, but can the figure be believed, the LEDs promise 25,000 hours, (at 3hrs a day = 23 years hmmm) The present mains halogen promise 5,000 hours but I doubt they come anyway near that. I was going to factor in 1 year for the halogen and 5 years for the LEDs...[/QUOTE]
Number of switchings on and off affects lifespan too.
Think might need a "Sheldon" out there with an algorithm

 

[Arch]

That looks uncannily like a bomb...

We got LEDs for our 6 bedroom up lighters, at a tenner each. If the figures are right, and given only a hour use a day, if that, we'll be leaving them in our wills.

 

[mr messy]

[QUOTE 2986017, member: 9609"]Big thanks to @slowmotion for loaning me a proper timer.

But did work out a bodge up that works. 12v transformer connected to a relay out of a car that controls the 1.5v battery powered alarm clock. Just wire the transformer up to the ceiling rose, and every time the lights are switched on the clock starts ticking ..... brilliant even if i say so myself,

[/QUOTE]
Erm don't be surprised to get a knock at the door in the early hours by dozen men in black with Heckler and Kochs.......

 

[cosmicbike]

All my 50W halogens, 12 in total at the moment (600W), were replaced with Phillips 3W LED GU10's (36W), which give very similar light levels and excellent colour rendering. I didn't pay more than £8 for each one, and in fact got 6 on BOGOF at Sainsburys. I didn't bother with timing stuff, just random guessed at how long they were on for.
Assuming 10p/Kwh, the halogens cost 60p for 10hrs, the LED's give 166hrs for the same cost.

 

[Custom24]

All my 50W halogens, 12 in total at the moment (600W), were replaced with Phillips 3W LED GU10's (36W), which give very similar light levels and excellent colour rendering. I didn't pay more than £8 for each one, and in fact got 6 on BOGOF at Sainsburys. I didn't bother with timing stuff, just random guessed at how long they were on for.
Assuming 10p/Kwh, the halogens cost 60p for 10hrs, the LED's give 166hrs for the same cost.

Yep, just checked and mine are similar. I replaced my 50w ones with Osram 4w 35w equivalents which were on offer in Robert dyas. They are slightly dimmer than the halogens, but not much.

 

[slowmotion]

[QUOTE 2986017, member: 9609"]Big thanks to @slowmotion for loaning me a proper timer.

But did work out a bodge up that works. 12v transformer connected to a relay out of a car that controls the 1.5v battery powered alarm clock. Just wire the transformer up to the ceiling rose, and every time the lights are switched on the clock starts ticking ..... brilliant even if i say so myself,

[/QUOTE]

Class! GCHQ is almost certainly studying that magnificent piece of boffinry as we speak. Do you need a detonator and some home-brew Semtex?

BTW, let me know if you still want my hours-run timer by PM.

 

[Smurfy]

[QUOTE 2985792, member: 9609"]At present in the kitchen, we have two mini tracks both supporting 4 x 50w mains halogen, that's a whopping 400watts (bloody ridiculous) [/QUOTE]
A long time ago I bought some low-energy (fluorescent) 7 watt E14 R50 bulbs from Ikea to replace some rather energy-hungry 50W spotlights. They take a minute to warm up, but after that they're ok. Ikea don't sell them anymore, but I think they are similar to these:

http://www.tradelighting.co.uk/mega...0-warm-white?gclid=CJ_Q7tvYn70CFcHnwgodSoUAuA

http://www.lamps-on-line.com/low-energy-r50-7w-e14-827.html

 

[Smurfy]

[QUOTE 2986384, member: 9609"]Good grief they wouldn't be allowed, anyway, 7w fluorescent would be as dull as dishwater.[/QUOTE]
How dull it is depends entirely on the space to be illuminated. I used to have eight in the kitchen, and that was dimmer than having 8 x 50W, but still plenty of light, and it cut my electricity by 85%.

 

[Smurfy]

[QUOTE 2986415, member: 9609"]As I said earlier I would just put up a couple of fluorescent tubes, I still think it is the best lighting, but I am not allowed to do that, My attempt to save-the-planet is handicapped by my wife who wishes her kitchen to be bathed in sparkling light.[/QUOTE]
'Sparkling Light'? Maybe you need to consider colour temperature (assuming you haven't already). Fluorescent tubes can be had in a variety of colour temperatures (same as LEDS) e.g. cold white, white, warm white.
http://en.wikipedia.org/wiki/Color_temperature#Lighting

 

[slowmotion]

For general illumination, low voltage halogens are pretty useless. They work well at highlighting small areas but you probably don't need that in a working kitchen. The thing is that a lot of people like their kitchens to be more than a strictly utilitarian space. I'm one of them. I stuck 12 recessed MR16 directional spotlighters in our kitchen ceiling in 1998. It was the fashion at the time. Quite mad really.....600 watts of lighting... and they don't actually give out much more light than 150 watts of incandescents.
Thank you all for pointing me in the direction of LEDs. The deal-breaker is how long they last. Manufacturers' figures on longevity are usually total balls. They test them under totally unrealistic conditions, not cycled on and off like ordinary people do.

 

[slowmotion]

[QUOTE 2986449, member: 9609"]I totally agree but they give this sparkling effect that some people like (I think they are a bit glaring and don't like them) . The recessed ones can be a total waste as all that heat energy is lost into the voids. not a complete waste when there is a room above, but if it is just loft space then that energy is mostly gone/wasted.[/QUOTE]

The room above has my Class A valve amplifier. 600 watts of glowing thermionic valves and hot copper transformers, no matter what the volume setting might be. It gets quite cosy.

 

[Fnaar]

I have a low tech solution: stand in the kitchen for several years, starting a stopwatch every time the lights get switched on.

 

[TeeQue]

Why didn't I think of the car!? I didn't mention relays because I just assumed you wouldn't have any lying around but of course there's loads in a car!

Nice bodge, I like it.