GU10 Verses MR16 Quality halogen lamps

Is there an equivalent GU10 halogen series similiar to the Osram IRC MR16 series. The GU10's I have seen to date are pretty ordinary.

Either 12V or a 240V solution. Ideally similiar effieciency to the IRC , good quality reflectors (Not made in China). Is going onto a C-Bus dimmer.

Cheers,

Fleetz

 

There is no way you can get the same efficiencies from a 240V MR16 as you can from a 12V.

This is because of 2 things - the higher efficiency from the higher filament current (of 12V) produces some gains, the physically smaller filament makes far better use of the tiny reflector.

I just did a study of the performance of various 50mm diameter reflector lamps. Basically, it was a number of calculations to determine the wattage (including transformer losses) required to achieve a certain light levels. The bottom line summary is ...

GU10 Halogen lamps are approximately 1/2 the efficiency of normal 12V lamps, and only 1/3 of the best IRC lamps

IRC Halogen is approximately 30% more efficient than high quality 50W 12V Halogen lamps

CFL 11W lamps have similar (overall) efficiency as a high quality 12V 50W

CFL 11W is approximately 20% less efficient than 50W IRC Halogen

For a given light level, must use 4.4 times as many 11W CFL lamps compared to 50W 12V (or Osram 35W IRC)

The most efficient (Lux in the room per Watt) is the Osram IRC...

50W GU10 = 16.67W per m? per 100 Lux
50W 12V Quality Brand = 7.88W per m? per 100 Lux
11W CFL = 7.1W per m? per 100 Lux
35W 12V Osram IRC = 5.7W per m? per 100 Lux

 

Hi John,

You blow me away!

You get into lighting pretty deep that information is amazing and very valuable information. Makes what I am having to go through with the dimmable ballast a farce.

So really what I have to do is put more flouro DLs (4.4X) to get the same light output to match what I was going to put in which was the Osram IRC's

I wonder if Malcom Turnbull is across the numbers!!

Cheers,

Fleetz

 

LOL - Lighting Energy Efficiency is what I do for a full time job now days.

For all lamps, the problem of getting efficiency relies upon a geometric relationship between light source size and reflector size. To create a decent beam and harness the light properly, the reflector (or louvre in a linear Fluoro) must be at least 7 times the width of the light source.

For a 240V GU10, the filament is very long and runs up/down in the reflector. The angles between filament and reflector simply do not work, so a lot of light cannot get harnessed properly by the reflector and chucked out where it needs to go.

For a 12V Halogen of same wattage, the filament is MUCH thicker and therefore is much shorter (and more sturdy too = longer life). The "glowing part" of a typical dichrioc lamp is probably 2mm x 5mm max. Placed axially (cheap lamps run transverse filaments) and you have an excellent lightsource (5mm) to reflector (50mm) ratio, so you get great beam control and efficency.

For the MR16-sized fluoros, a T2 tube is wound up into a tiny series of loops. Check the attached file - see how the only part that can actually produce direct light is the 6 ends of the loops? The rest of the light output simply bounces around inside the housing, and eventually "falls out". Heaps is wasted by re-radiation back into the fluoro tube.

A standard TC (PL) type 11W fluoro produces 900 lumens. The Megaman 11W uses just over 11W including ballast losses, so they probably use a 7 to 9W tube of about 400-500 lumens. Already, they are about 1/2 what a bare 12V 50W or 35W IRC Halogen produces (900 lumens). Then, due to inefficiencies of the reflector, only about 1/2 of that can actually get out into the room, the rest is wasted.

Note that these comments ONLY apply to the MR16 size CFLs - other CFL lamps are far more efficienct than halogen providing they are inside a light fitting that is big enough to actually let some light out !

Compact fluorescent lamps are not ALWAYS the best thing for energy efficiency. One particular problem with the compact fluoros is the terrible light output until they warm up - they are definitely not a "instant-on" light source. So, the tendency is therefore to leave them switched on, where a Halogen can immediately porovide power.

Keep in mind that a 11W CFL left switched on for 4 hours uses far more power than a 50W Halogen used for 10 minutes... because what really matters is kWh = kilo Watt hours !!

 

Oh - and just clarifying that the calculations I performed were based on IES photometric data supplied by the manufacturers. But it's easy to see for yourself - try it and you'll be amazed how poor other lamps are in comparison to an IRC lamp.

If you want energy efficiency, use 20W IRC, and stick 3 per transformer. That way you minimise the losses to only 2W per lamp (22W per lamp in total) and still get about twice as much light as the 11W CFLs. Plus you can DIM the halogens

 

Hi John,

Here I was thinking you were a rocket scientist!

Excellent summary indeed from someone who obviously is committed to his chosen field.

I concur with your final suggestion having been again blown away with the facts present. I have already purchased a number of lights GU10 halogen, Osram IRC, Chinese crap halogens, "Normal MR16 halogen", Megamann 11w CFL and I agree the IRC is streets ahead and what I would like to use through out the house (garage excluded) however I have to work around the Bl*#^@y regulations in place in QLD.

This is the reason I am scratching new ground with initially DALI and now with some excellent guidance DSI and 0-10V using dimmable ballasts.

I have spent a good hour or two looking for dimmable ballasts and downlights (with those pesky 4 pin connectors) and there isn't many suppliers jumping out saying "let it be me"!!

What I want to do is just buy a couple of likely suspects in ballasts and downlights (ones with a nice size opening John) probably around 130mm and experiment with them. Looking at light output (I have a lux meter) colour temperature, start up time etc etc. and wheter I can live with fluoros in our living areas!

Cheers,

Fleetz

 

Another undesirable aspect of GU10 is that when the filament blows it can cause

a) A dimmer channel to blow
b) RCD to trip
c) Control unit reset (powers down and up again)

Its so annoying to have channels missing only because the lamp reached End-Of-Life and had some kind of obscene current draw. Yet it is so transient that it does not blow the RCD till it is too late.

The early Phillips GU10 lamp holders were a total POS. On the first lamp change the lamp holder crapped out and no longer took lamps. So I ended up changing all of the original holders with the initial globe change.

I prefer 12V because it "isolates" the lamp from the dimmer unit.

The GU-10 lamps give a very warm light. Much closer to the light bulbs they replace.

 

That would be a sticker made in a Chinese factory to fool people.

 

Reverse psychology!