Electric-Light
Senior Member
The InstantFit is line of phosphor fluorescence based LED T8 lamps that is compatible with some instant-start T8 fluorescent electronic ballast.
The earlier version used plastic and despite their skewed and clever marketing attempts, the output is considerably lower than 25W 48" T8.
The newer, cheaper version uses shatterable glass bulb. The LED strip is glued to the back of the glass tube and ditches the aluminum tray insert. This must be their small business/DIY market. Higher output, but correspondingly higher power consumption. Endurance is shaved down 28% to 36k hrs to 30% LED degradation.
Philips rates everything based on 0.88 BF two lamp ballst of their choice. They recognize use with high BF ballast, but explicitly say life rating is only valid for BF 0.88 or less. This means high BF = faster degradation as well as lower lumens per watt.
My analysis:
The InstantFit LED costs slightly less per lamp than 2XL 25W HPT8 and boasts a refreshing 11.9% lead fresh out of the box efficacy of 105 lm/W and look fabulous on post-installation evaluation. This isn't for long as it goes on a steady down hill rides before cutting off at 73.5 lm/W at 36K hours. The hot temperature characteristics look comparable and cold temperature performance is much better. It is indeed a great fluorescent substitute for low hour applications, such as storage rooms and residential use that sees frequent short cycles. Nonetheless, it falls significantly short of high quality long life traditional fluorescent technology in long burning applications these lamps are generally marketed to, such as convenience stores and small business offices.
The real implication is that overcoming lamp degradation that far exceeds F40T12 requires the use of old approach used for metal halide lamps which is to of overshoot by a large amount so that initial lumen is 43% above the acceptable minimum level or costly active control that is beyond the scope of this thread. Overshoot only needs to be 8.6% for 8% degradation of HPT8 2XL. When lamps go out on a T8 fluorescent lamps, the remaining lamps get driven a bit harder which cancels out some of output drop due to lamp burn outs. There's no compensation for LED fouling. The useful life of InstantFit T8 is considerably lower than 2XL fluorescent and the performance during lifecycle is rather poor.
I was conservative in using 50K hours to assume group replacement at 10% outage while very generous to the LED for letting it use the entire rated life and assume zero total failure.
LED marketing department love fresh out of the box specs, because it makes them look more presentable. Lower upfront cost means LEDs are driven hard to reduce chip quantity. The initial performance is of little relevance for something whose selling point is extreme durability. What really got rare earth bearing T8 systems ahead is the lower degradation that allowed systems to be designed with less initial overshoot. Allowing LEDs to get away with degradation performance worse than F96T12/HO/CW/110W is a step backward.
There is a higher spec line offering 18W/2500 lm, 70K hours to 30% degradation avaiable, but you have to pay considerably more for this upfront.
Reference benchmark: Philips 2XL T8 25W $6.90/lamp @ HD Supply
48" T8 25W. 2110 new lamp lm at 22.5W line input per lamp. 1940 LM (92%)@ 60k hrs.
B50@68K hrs. L10 (10% outage) would be about 50K hrs on 12 hour cycle.
Older InstantFit:
Plastic.
1650 new lamp lumens per 16 system watts. 50,000 hr rated life to 30% LED degradation.
170 degree beam spread. $20+/lamp
New version: InstantFit LED T8 - 4' Glass. $6.35/lamp in 10 pack @ Home Depot
Shatterable GLASS
2100 new lamp lumens per 20 system watts. (rated on 0.88 BF)
2450 new lamp lumens per 26.5 system watts (at 1.18 BF.. life rating not valid under this use)
36,000 rated life.(DLC listed, therefore color stability isn't a requirement and color shift can force early retirement not covered under warranty)
Read here for more information about L70/B50 rating http://www.osram-os.com/osram_os/en...chnology/2014/how-long-do-leds-last/index.jsp
References consulted:
Philips InstantFit product bulletin
http://images.philips.com/is/conten...01_UPD_en_US_PLt-1309BN_LED T8_Web_682016.pdf
Philips T8 48" 25W 2XL specification sheet
2XL T8 fluorescent lamp:
Advance 2 lamp ballast datasheet
The earlier version used plastic and despite their skewed and clever marketing attempts, the output is considerably lower than 25W 48" T8.
The newer, cheaper version uses shatterable glass bulb. The LED strip is glued to the back of the glass tube and ditches the aluminum tray insert. This must be their small business/DIY market. Higher output, but correspondingly higher power consumption. Endurance is shaved down 28% to 36k hrs to 30% LED degradation.
Philips rates everything based on 0.88 BF two lamp ballst of their choice. They recognize use with high BF ballast, but explicitly say life rating is only valid for BF 0.88 or less. This means high BF = faster degradation as well as lower lumens per watt.
My analysis:
The InstantFit LED costs slightly less per lamp than 2XL 25W HPT8 and boasts a refreshing 11.9% lead fresh out of the box efficacy of 105 lm/W and look fabulous on post-installation evaluation. This isn't for long as it goes on a steady down hill rides before cutting off at 73.5 lm/W at 36K hours. The hot temperature characteristics look comparable and cold temperature performance is much better. It is indeed a great fluorescent substitute for low hour applications, such as storage rooms and residential use that sees frequent short cycles. Nonetheless, it falls significantly short of high quality long life traditional fluorescent technology in long burning applications these lamps are generally marketed to, such as convenience stores and small business offices.
The real implication is that overcoming lamp degradation that far exceeds F40T12 requires the use of old approach used for metal halide lamps which is to of overshoot by a large amount so that initial lumen is 43% above the acceptable minimum level or costly active control that is beyond the scope of this thread. Overshoot only needs to be 8.6% for 8% degradation of HPT8 2XL. When lamps go out on a T8 fluorescent lamps, the remaining lamps get driven a bit harder which cancels out some of output drop due to lamp burn outs. There's no compensation for LED fouling. The useful life of InstantFit T8 is considerably lower than 2XL fluorescent and the performance during lifecycle is rather poor.
I was conservative in using 50K hours to assume group replacement at 10% outage while very generous to the LED for letting it use the entire rated life and assume zero total failure.
LED marketing department love fresh out of the box specs, because it makes them look more presentable. Lower upfront cost means LEDs are driven hard to reduce chip quantity. The initial performance is of little relevance for something whose selling point is extreme durability. What really got rare earth bearing T8 systems ahead is the lower degradation that allowed systems to be designed with less initial overshoot. Allowing LEDs to get away with degradation performance worse than F96T12/HO/CW/110W is a step backward.
There is a higher spec line offering 18W/2500 lm, 70K hours to 30% degradation avaiable, but you have to pay considerably more for this upfront.
Reference benchmark: Philips 2XL T8 25W $6.90/lamp @ HD Supply
48" T8 25W. 2110 new lamp lm at 22.5W line input per lamp. 1940 LM (92%)@ 60k hrs.
B50@68K hrs. L10 (10% outage) would be about 50K hrs on 12 hour cycle.
Older InstantFit:
Plastic.
1650 new lamp lumens per 16 system watts. 50,000 hr rated life to 30% LED degradation.
170 degree beam spread. $20+/lamp
New version: InstantFit LED T8 - 4' Glass. $6.35/lamp in 10 pack @ Home Depot
Shatterable GLASS
2100 new lamp lumens per 20 system watts. (rated on 0.88 BF)
2450 new lamp lumens per 26.5 system watts (at 1.18 BF.. life rating not valid under this use)
36,000 rated life.(DLC listed, therefore color stability isn't a requirement and color shift can force early retirement not covered under warranty)
Read here for more information about L70/B50 rating http://www.osram-os.com/osram_os/en...chnology/2014/how-long-do-leds-last/index.jsp
References consulted:
Philips InstantFit product bulletin
http://images.philips.com/is/conten...01_UPD_en_US_PLt-1309BN_LED T8_Web_682016.pdf
Philips T8 48" 25W 2XL specification sheet
2XL T8 fluorescent lamp:
Advance 2 lamp ballast datasheet
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