Electric-Light
Senior Member
Intro
Electricians, utilities, facility owners and anyone interested in realistic performance of the typical existing T8 lighting systems and retrofit, modification and upgrade options should read this post for continuing education or as a resource to help make an informed decision. This post is compiled from realistic stuff. It doesn't go along with the interest of LED Sales Representatives looking for ways to get LEDs to move through the pipes or sell LED installs. Sidenote: LEDs did make huge improvements in the past few years.
Average existing T8
Snapshot of a system representative of overwhelming majority of T8 systems
Baseline
Efficiency for 2 lamp system using the basic model ballast and cheap lamps from early 2000s.
About 85 LPW with new lamps. About 80 LPW maintained.
About 90/(85) for 4 lamp systems.
Wattage input for basic early 2000s systems with 32W lamps
1L: 30W 2L: 59W 3L: 86W 4L: 112W
Existing T8 Ballasts:
Vast majority of T8 lights use an instant start electronic designed to run lamps to push 87-89% of their spec lumens. Best efficiency ballasts sold today are a couple percent more efficient than the typical ones from early 2000s. Not that much. +4-5% more efficient for 2 lamp. +2-3% for 4 lamp.
Sales managers from "rewire LED" shops can probably track down a magnetic ballast for two F32T8 that draws 75W and rated 1.0BF. Such a ballast exists in catalog, but they are RARELY used.
Existing T8 Lamps
The cheapest basic lamps: 700 series 32W 78 CRI, 4100K.
Philips... in 2002 catalog: 2850, 2710@8000hrs. 20K hr life.
Sylvania in 2010 catalog: 2800, 2520@10000hrs. 25K hr life.
Worse lamps exist if you look hard.
Fixtures
Fixtures can range anywhere from 50-95% efficient depending on light pattern. Example for modern high efficiecy recessed type. Kenall 1x4 CSEFO14P is at 83.4%. 2x4 @ 85% using fluorescent lamps. These are ITL Boulder tested values, so I trust it. http://www.kenall.com/Kenall-Files/Product-Files/specificationsheets/CSEFO14P.pdf
Deteriorated reflectors and fixtures that don't do a good job of directing the light from upper half of the lamps to where it's needed unduly favor LEDs retrofits.
Upgrade options for indoor use
Premium T8 drop in.
Wait until you need to replace the lamps.
No change in light pattern for fluorescent drop-ins.
Material: $4.16 to 5 per lamp
Labor: none if you wait until you're due for re-lamp. Additional if the fixtures are dirty and need cleaning.
$4.16/ea for 32,000/38,000hr rated (3 hr per start, 12hr per start)
$5/ea for 40,000/46,000 XLL. Competitive with LED's life.
(HOME DEPOT online in case quantity, delivered. 30/cs)
I think its more reliable than LED claims. We've had T8s since 1990s and tens of thousands of real life usage, so I think there's enough data to support the light loss prediction.
LEDs are only tested to 6,000 hrs. Engineers think that deterioration settle down after those 6,000 hours and the rated life is EXTRAPOLATED to guess how many hours it takes to drop to 70% of new output. I don't know of any GSFL linear lamps that lose anything close to 30%.
Electricians, utilities, facility owners and anyone interested in realistic performance of the typical existing T8 lighting systems and retrofit, modification and upgrade options should read this post for continuing education or as a resource to help make an informed decision. This post is compiled from realistic stuff. It doesn't go along with the interest of LED Sales Representatives looking for ways to get LEDs to move through the pipes or sell LED installs. Sidenote: LEDs did make huge improvements in the past few years.
Average existing T8
Snapshot of a system representative of overwhelming majority of T8 systems
Baseline
Efficiency for 2 lamp system using the basic model ballast and cheap lamps from early 2000s.
About 85 LPW with new lamps. About 80 LPW maintained.
About 90/(85) for 4 lamp systems.
Wattage input for basic early 2000s systems with 32W lamps
1L: 30W 2L: 59W 3L: 86W 4L: 112W
Existing T8 Ballasts:
Vast majority of T8 lights use an instant start electronic designed to run lamps to push 87-89% of their spec lumens. Best efficiency ballasts sold today are a couple percent more efficient than the typical ones from early 2000s. Not that much. +4-5% more efficient for 2 lamp. +2-3% for 4 lamp.
Sales managers from "rewire LED" shops can probably track down a magnetic ballast for two F32T8 that draws 75W and rated 1.0BF. Such a ballast exists in catalog, but they are RARELY used.
Existing T8 Lamps
The cheapest basic lamps: 700 series 32W 78 CRI, 4100K.
Philips... in 2002 catalog: 2850, 2710@8000hrs. 20K hr life.
Sylvania in 2010 catalog: 2800, 2520@10000hrs. 25K hr life.
Worse lamps exist if you look hard.
Fixtures
Fixtures can range anywhere from 50-95% efficient depending on light pattern. Example for modern high efficiecy recessed type. Kenall 1x4 CSEFO14P is at 83.4%. 2x4 @ 85% using fluorescent lamps. These are ITL Boulder tested values, so I trust it. http://www.kenall.com/Kenall-Files/Product-Files/specificationsheets/CSEFO14P.pdf
Deteriorated reflectors and fixtures that don't do a good job of directing the light from upper half of the lamps to where it's needed unduly favor LEDs retrofits.
Upgrade options for indoor use
Premium T8 drop in.
Wait until you need to replace the lamps.
No change in light pattern for fluorescent drop-ins.
Material: $4.16 to 5 per lamp
Labor: none if you wait until you're due for re-lamp. Additional if the fixtures are dirty and need cleaning.
- 28W drop-in A very close match for basic 32W 700 series lamp.
About 12% reduction in watts, same output.
Power usage(typical) 52W for 2lamp. 98W for 4L.
- 25W drop-in. Reduction to about 2000-2100 lumens per lamp.
about 10% reduction in light.
About 22% reduction in watts.
Typical watts: 46W for 2L, 87W for 4L.
Good: economical. Unparalleled lumen maintenance. 94% lumen maintenance after 40,000 hr burn time.
Bad: Not for use below 60F.
$4.16/ea for 32,000/38,000hr rated (3 hr per start, 12hr per start)
$5/ea for 40,000/46,000 XLL. Competitive with LED's life.
(HOME DEPOT online in case quantity, delivered. 30/cs)
I think its more reliable than LED claims. We've had T8s since 1990s and tens of thousands of real life usage, so I think there's enough data to support the light loss prediction.
LEDs are only tested to 6,000 hrs. Engineers think that deterioration settle down after those 6,000 hours and the rated life is EXTRAPOLATED to guess how many hours it takes to drop to 70% of new output. I don't know of any GSFL linear lamps that lose anything close to 30%.