T12 bulbs in T8 fixtures saves watts. For real. Constant current circuit

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Electric-Light said:
Name a handful of LED products that you purchased or were available for purchase 18 months ago for which you can get aesthetically harmonious both in off and on state without disrupting the original specification requirements.
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None, and that is actually a sign of progress. LEDs are evolving, and those made today will be phased out by ones that are even more efficient, cooler running and long lasting tomorrow. It won't be long until they start making LED oven bulbs that look identical to what your replacing.



peter d said:
:happyyes::happyyes::thumbsup:
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Just got some of these for my home:

LED-Filament-Bulbs.jpg



I can truly say that within a year or two we will have A19 bulbs that produce light indistinguishable from an incandescent even to the most discerning eye- and A21 LED bulbs that will cover 300 watt and 3 way lighting at a comparable cost. Everything thus far has just been a transition. And its a good thing thats happening:


http://dailycaller.com/2017/01/20/obama-outlaws-more-light-bulbs-on-his-way-out-the-door/

http://www.washingtonexaminer.com/w...-outlawed-your-three-way-bulb/article/2612397


Sneaky yes, but considering that bulb efficiency has gone from 1-2% to over 90% and climbing its not all to bad.
 
Electric-Light said:
As the only downside, the lamp wears out significantly quicker because filaments are designed to operate at a certain amperage and when the current is reduced without giving some auxiliary cathode heater power, the electrodes tend to sputter away and blacken the lamp.
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sputtering is often a problem with this topic, i'll agree.

is your premise that we should buy T-12 lamps, and put them in
T-8 fixtures?
 
Fulthrotl said:
is your premise that we should buy T-12 lamps, and put them in
T-8 fixtures?
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No, I'm just dropping a quick fact that installing T12 into T8 fixture will light up and stabilize in most T8 electronic ballasts and you can get a wattage reduction with proportional light loss that is consistent with many LED retrofits. T12s are rated 24,000hrs or so. If you only get 20% life, that's still a decent 4,800 hrs. That's about half the rated life of CFLs and some budget LEDs.

It's exploring the side of wattage reduction that doesn't require the purchase of costly LED retrofit service and still provide adequate/tolerable level of light. The quality of light is the same as LEDs and T8 for those who happen to have access to high quality surplus T12 lamps like SP35/41, SPEC35/41 to spend down and ok with a relatively short life. 4,800 hrs is still close to two years for a small business that averages 50hrs/week of use. The only cost is time or labor to relamp.

I wouldn't purchase T12s unless you're talking about ReStore find for buck a case or something for RE80 T12 lamps. If you have to buy lamps, the low wattage lamps is the way to go for indoor.

T8 system initial performance cheat sheet. (note: decay is lesser than LEDs)

Numbers shifted a bit for ease of remembering, but they're close. Use these values over instead of anything provided by LED sales rep. Optical performance factors are more complex and not included. Those affect LEDs as well.

32w lamps 2600lm out per 28 w in
28w lamps 2500lm out per 25w in
25w lamps 2222lm out per 22.2w in


mbrooke said:
None, and that is actually a sign of progress. LEDs are evolving, and those made today will be phased out by ones that are even more efficient, cooler running and long lasting tomorrow. It won't be long until they start making LED oven bulbs that look identical to what your replacing.

Just got some of these for my home:

LED-Filament-Bulbs.jpg
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Those are decorative lamps. If you break one of them or the ballast molded into the base fails, there is a chance you have to replace the whole set at once to maintain aesthetic harmony. Visually, the odd shaped one like the one on left would be hard to replace. Dimming inconsistency of different replacement affects them all the same. This is perhaps planned obsolescence to produce demand by forcing people to replace the entire set.

Sneaky yes, but considering that bulb efficiency has gone from 1-2% to over 90% and climbing its not all to bad.
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LEDs are nowhere near 90% efficient.
 
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Those are decorative lamps.
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Of course, I posted clear envelopes to show forum viewers the filament deisgn. Here is the general use version also using the same concept:


https://www.greenliteusa.com/en/lights/1928-led-7w-omni-frost-a19-filament.html

As soon will PAR and high wattage lamps.



If you break one of them or the ballast molded into the base fails, there is a chance you have to replace the whole set at once to maintain aesthetic harmony.
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And this would be of great enough concern (likely to get noticed) to warrant using 5x more energy, especially when the lamp happens to be none decorative ie general purpose for an enclosed flushmount?




Visually, the odd shaped one like the one on left would be hard to replace. Dimming inconsistency of different replacement affects them all the same. This is perhaps planned obsolescence to produce demand by forcing people to replace the entire set.
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How do they dim inconsistently?

LEDs are nowhere near 90% efficient.
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Can you show me the data on here?
 
wwhitney said:
Check out the wikipedia page on "luminous efficacy":

https://en.wikipedia.org/wiki/Luminous_efficacy

A hypothetical 100% efficient electric light source would produce 683 lumens/Watt. So if an LED is producing 95 lumens/Watt, it is about 14% efficient. The rest of the power is going into light outside the visible range or heat.

Cheers, Wayne
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I was looking into that a while back, yes it kinda depressing. Its amazing how little (theoretical) energy it takes to make visible light. Analogous is the refrigeration cycle, where a perfectly efficient refrigeration cycle (called a carnot cycle) would use about a tenth of the energy that the most efficient units today use :rant:
 
wwhitney said:
Check out the wikipedia page on "luminous efficacy":

https://en.wikipedia.org/wiki/Luminous_efficacy

A hypothetical 100% efficient electric light source would produce 683 lumens/Watt. So if an LED is producing 95 lumens/Watt, it is about 14% efficient. The rest of the power is going into light outside the visible range or heat.

Cheers, Wayne
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Ok, now Im confused. :? I swear I read several places that a mercury vapor was about 15-20% efficient, MH about 40% max, HPS about 50%, LPS 80% and LED close to 90%. What am I missing :huh:
 
wwhitney said:
Check out the wikipedia page on "luminous efficacy":

https://en.wikipedia.org/wiki/Luminous_efficacy

A hypothetical 100% efficient electric light source would produce 683 lumens/Watt.
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Followup: the 683 lumens/watt figure is achieved by a monochromatic light source, so the CRI would be beyond lousy. If you ask for a CRI of 95 or above and a color temperature of 2800K, then the best theoretically possible is 370 lumens/watt.

Cheers, Wayne
 
wwhitney said:
Followup: the 683 lumens/watt figure is achieved by a monochromatic light source, so the CRI would be beyond lousy. If you ask for a CRI of 95 or above and a color temperature of 2800K, then the best theoretically possible is 370 lumens/watt.

Cheers, Wayne
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I do not doubt this, but I swear I read several places that the efficiency was as I noted above. :blink: I know you guys are right, but what was I seeing? Was it a marketing spin?
 
mbrooke said:
Ok, now Im confused. :? I swear I read several places that a mercury vapor was about 15-20% efficient, MH about 40% max, HPS about 50%, LPS 80% and LED close to 90%. What am I missing :huh:
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Maybe you (and your other source) are missing what energy is converted to non visible spectrum?
 
kwired said:
Maybe you (and your other source) are missing what energy is converted to non visible spectrum?
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Its not so much that I am missing, just that lighting is not one of my strong subjects and always assumed what I read to be true. But its good that I learned something today :)


kwired said:
I suppose my previously mentioned gas lamps and kerosene lanterns don't meet DOE efficiency requirements:(
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At least I can grasp this :thumbsup::)
 
FWIW

When we replace HID or flouresent fixtures with LED the current drops by 1/3 to 1/2 what it was and the lighting levels appear the same.
 
iwire said:
FWIW

When we replace HID or flouresent fixtures with LED the current drops by 1/3 to 1/2 what it was and the lighting levels appear the same.
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An increase in efficiency, but not to 100%. Power factor can skew the apparent results though.
 
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