lights on dimmer units to no more than 90%

Discussion in 'C-Bus Wired Hardware' started by [email protected], Sep 28, 2005.

  1. arnis@nyherji.is

    [email protected]

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    It has been talked about that it is good for lightbulbs to never be on at 100% and one should config the dimmer units to only go to 90% to extend light bulb life.

    can anyone confirm that this is true and that C-Bus installers do this as a standard practice ?

    Thanks
    Arni
     
    [email protected], Sep 28, 2005
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  2. arnis@nyherji.is

    PSC

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    Reducing the dimmer output to 90% will increase the lamp life by 4 times, the lumen output will be reduced to 69%.

    If you reduce the dimmer output to 95% you will double the life of the lamp, the lumen output will be reduced to 82%.

    I wouldn't say it was common practice, but customers do ask for it from time to time.
     
    PSC, Sep 28, 2005
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  3. arnis@nyherji.is

    znelbok

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    I have also seen comments that if you do do this then you need to occasionally run them at 100% to burn the crap of the filament. I am not sure if this relates to elv lights only. Do a search and you will find some old threads about this topic and what some people do

    Mick
     
    znelbok, Sep 28, 2005
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  4. arnis@nyherji.is

    UncleSam

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    Zen, the 100% burn thing is predominently for LV halogen lamps so that the gas gets hot enough to re combine any tungstan floating about back to the filiment I don't believe that there is a requirement to do this with normal incandescent globes.

    arnie, as PSC says there is a reduction in light level when you under run globes, and this does equate to longer life (as does the C-bus dimmers built in 'soft start' that ensures that rather than being turned hard on the lamp is always ramped up over ~400ms). However because your eye is not sensitive to changes in brightness of bright light a 25% or so drop in light output doesn't look like 25% less light to your eye so it's not as bad as it sounds
     
    UncleSam, Sep 29, 2005
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  5. arnis@nyherji.is

    [email protected]

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    thanks for the responses guys

    I have set all my dimmer channels to 90% max, it will be intrested to see how bulb life will be affected.

    And as you said the softstart also helps, I have seen this especlay in my 240V Halogens, they seem to last much longer beacuse of softstart.
     
    [email protected], Sep 30, 2005
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  6. arnis@nyherji.is

    JohnC

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    That "Run the lamps at 100% occasionally" is an urban myth.

    When dimmed, the Tungsten Evaporation Rate decreases at approximately the same rate as the Halogen Cycle (that replaces the Tungsten upon the filament).

    If the lamp is running at reduced power, then the tungsten filament evaporation is reduced (proportionally). Therefore - if you dim the lamps, the bulbs don't get blackened with evaporated tungsten as fast, so there's not as much need for the Halogen Cycle to replace the tungsten back onto the filament.

    Just think about it and you will figure it out.

    I have dimmed halogen lamps in my own house that are over 10 years old. The bulbs aren't blackened AT ALL... however the silver dichroic coating has completely disappeared on most of them !

    Cheers, john
     
    JohnC, Oct 13, 2005
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  7. arnis@nyherji.is

    Don

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    Spot on

    Glad to see someone debunking that myth.

    I remember one of the technicians conducting an experiment over a period of at least 1 year, where a halogen lamp was left running continuously at approximately 50% brightness in the old Clipsal lab. No visible blackening was discovered. We were satisfied, the report was filed, and we went ahead and developed a few dimmer products especially for this type of lamp. That was about 15 years ago.

    I don't think we could have had much impact in trying to convince others.. myths are sticky.. and besides, we always had a nagging doubt that there might be SOME condition under which the lamps would blacken.. otherwise how did the myth get started in the first place? In any case, we were happy that using a dimmer would not be a problem.

    By the way, I've been running halogens at up to 95% without any darkening effects for a 7 year period at home as well.

    Don
     
    Don, Oct 14, 2005
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  8. arnis@nyherji.is

    JohnC

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    More Info : Dimming Tungsten Halogen Lamp vs Life

    Hi everyone,

    I just found a training presentation I made about this subject - See the attached JPGs

    The graphs were sourced from Osram training materials (a CD for internal usage), but the info is available from other sources as well.

    Refer Slide : "Halogen_Dimming2" [37KB]

    Tungsten Evaporation (bulb blackening) is only significant down to approximately 70% of rated Voltage (30% light output). Below that level, the lamp is running so "cool" (filament is glowing orange, not yellow let alone white) that there is almost zero evaporation.

    The Halogen Cycle functions down to approximately 60% of Rated Voltage (20% light output).

    Refer Slide : "Halogen_Dimming" [41KB]

    At 60% Voltage, lamp life would be many, many hundreds of times longer than Rated Life (95% voltage = life doubled, 90% = quadrupled, etc)

    Dimming below 60% means that lamp life is almost infinity, in which case there will be other reasons that the lamps will need to be changed.

    Perhaps after 50 or 100 years (of running at 60% voltage or less) there might be some bulb blackening, but it's completely irrelevant in the overall scheme of things :D

    -----------------

    Hope that helps - Cheers, John
     

    Attached Files:

    JohnC, Oct 14, 2005
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  9. arnis@nyherji.is

    Don

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    quirky things

    Thanks, John

    I'm very much looking forward to working with LED lighting. These will have their own quirks, of course, but I think the days of either

    1) hot, humming dichroic lamps and associated gear or
    2) ugly, flickering, slow-starting, non-dimmable mercury-filled fluoros

    are soon coming to an end.

    By the way, I notice legislation is being introduced in many places (California, Queensland, etc.) which will make dichroic lamps pretty scarce very soon.

    The next 5 years in this industry is going to be a lot of fun!

    Don
     
    Don, Oct 14, 2005
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  10. arnis@nyherji.is

    JohnC

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    Hi Dan,

    From watching and working with LEDs for the past 5 years or so, I'd say that they have a VERY LONG way to go before they take sales away from other light sources.

    They are NOT efficient, the output of the best white ones is only about the same as halogen (20-30 lumens per watt). And they get TOO HOT to be reliable... a 3w LED needs a substantial heatsink or it will self-destruct !

    Also, the white LEDs are inherently flawed, in that they are actually a blue LED with a yellow phosphor coating at the front to make the appearance of "white". The blue LED might last for 60,000 hours, but the phosphors will be long gone by that time !

    Final nail is the price. We are supplying a large project at the moment where around 200 decorative wall lights are being supplied with High Output LEDs instead of 40w G9 Halogen. The conversion cost (incl gear) is about $150 EACH - no way that you could consider that reasonable or economically viable !

    ----------------

    Fluorescents can do everything on your "wish-list" right now... but you need to use Electronic Control gear. They don't flicker, they start immediately, dimming is very effective. The mercury dose has been reduced to a TINY amount in modern tubes (eg: Philips Alto). For better appearance, use a compact fluroescent rather than linear :)

    ----------------

    Yes, the new MEPs for buildings will have a significant impact on the industry. It is a real pity that the Government has to FORCE people to use their common sense !

    Dichroics etc will still be allowable, providing the overall project meets a specified Watts per sq. Metre. I'd say that people will use Fluoro and Metal Halide (80lm/w) in general areas and display lighting, and use Halogen (25lm/w) as feature lighting only.

    However, when all is said and done, there are many applications where a LV Halogen simply is the best thing for the job... remember that we don't all drive around in the latest technology, most fuel-efficient cars do we ?

    John
     
    JohnC, Oct 17, 2005
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  11. arnis@nyherji.is

    Don

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    Not so much the LEDs but the Legislation

    John,

    My main worry is not so much the new LEDs. I acknowledge that the efficiency of most LEDs currently available is not good, but note that there are a few companies in US offering complete LED luminaires with over 40 luments/watt light output which is as good as some CFL lamps. LEDs themselves can be found with 60 lumens / watt. It will come eventually.

    I am surprised at your quoted efficacy for halogen lighting (25lm/w). The references I've seen are 10 to 19lm / W including transformer losses.

    In Queensland at the moment, there is draft legislation, to be introduced on 1 March, 2006, which demands that 40%, no less, of floor space inside domestic dwellings be externally ballasted CFL or linear fluorescent lamps. No other option.

    40% is significant, and you won't get away with a fluoro in the bathrooms and in the shed anymore. The intention of this legislation is to cut down incandescent lighting.

    Draft legislation:
    http://www.lgp.qld.gov.au/docs/building_codes/queensland_development_code/QDC_Part29_draft.pdf

    More information:
    http://www.qccqld.org.au/files/LGPsuHousing.pdf.

    Don
     
    Last edited by a moderator: Oct 20, 2005
    Don, Oct 17, 2005
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  12. arnis@nyherji.is

    JohnC

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    Whilst I didn't say so, I was referring to current "best practice" for Halogen - using the IRC type lamps, and Low Voltage ones being operated on Electronic gear.

    Using a quality electronic transformer, you should use 3-5w loss maximum per transformer. Using multiple lamps per transformer increases system efficiency and reduces the up-front cost significantly. Figures for common Low Voltage would therefore be :

    2 x 35w on a 70VA transformer :
    - each lamp 900lm using 37w total = 24.32 lm/W

    1 x 50w on a 70VA trans :
    - lamp 1250lm using 54w = 23.15 lm/W

    2 x 50w on 100VA trans:
    - lamp 1250lm using 52w = 24.04 lm/W

    So, I guess I was a little bit off when I posted "25 lm/W", but not by much.

    HOWEVER - using cheap crappy lamps, and conventional transformer is a completely different story ! And the one that 99% of domestic installations use :

    50w crap lamp on 50VA wire-wound trans
    - lamp 850lm using 65w = 13.07 lm/W

    -------------------------

    Even more interesting is to compare these properly - in other words, not just lumens per watt but the actual installed loads based on a certain light level.

    So, lets compare the difference of 4 downlights in a lounge room. We will assume that the "requested" lighting was 4 x cheapo 50w lamps (as used by almost every builder, due to cost) :

    4 x 50w crap lamps on 4 x 50VA wire-wound trans
    - each lamp 900lm - using 260w total
    -vs-
    4 x 35w IRC lamps on 2 x 70VA transformer :
    - each lamp 900lm - using 148w total

    So, there's a 112w or 43% power saving. If they were run 5 hours per day, 365 days a year, that's 204.4kW/h and at 10c/kWh that equates to a saving of $20 per year off your electricity bill (just for ONE ROOM). And, it saves about 200 Kilograms of CO? being released each year.

    And what is silly about it is that the total installed cost for both systems is approximately THE SAME... :eek:

    -------------------------

    Anyway that's enough ranting for now, John
     
    Last edited by a moderator: Oct 31, 2005
    JohnC, Oct 31, 2005
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  13. arnis@nyherji.is

    Don

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    This is exactly the reason why I dread this new legislation.

    I know "thou shalt use externally ballasted fluoros" is easy to say, and possible to police, but it could still result in inefficient lighting if poor quality fittings are installed, and/or installed in silly ways and/or operated with no regard to energy management.

    The legislation will give nobody the chance to install any other type of lighting in a way that can save the same, or more energy.

    Don
     
    Don, Oct 31, 2005
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  14. arnis@nyherji.is

    JohnC

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    LOL, yeah, what would be more efficient :
    - Using 4 x 26w Compact Fluoros
    - OR using 1 x 100w incandescent lamp

    Each one of the CFLs might be more efficient, but there's a lot more to energy savings than that.

    This is a good reason for ppl in QLD to strongly oppose the "MEPs for Buildings" rubbish while it's still a draft. As far as I know it was proposed in NSW and other states and kicked out almost immediately by the industry bodies because it was stupid, unworkable and irrelevant.

    Lighting uses only a small proportion of electricity usage, domestic lighting a small proportion of that proportion ! So any savings made by legislation like you're mentioning is about as relevant as trying to stop beach erosion by saving 8 grains of sand from every beach. :rolleyes:

    I am all in favour of saving energy, and we can make a difference. But it's better to set criteria (eg: max 20w per sq. metre overall) and let the designers work out the best way to cope with it. All the Australian Standards for lighting are written that way - they do not say HOW to do it, but just state what is required.
     
    JohnC, Oct 31, 2005
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  15. arnis@nyherji.is

    Don

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    Well said John!
     
    Don, Nov 1, 2005
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