I just completed a job where I swapped out existing 400W MH fixtures for T5 HO fluorescents. To be honest, I was skeptical of this project when it was pitched to me 2 months ago. The application is in a warehouse/distribution center with pick aisles 150' long, 50" wide and with shelving 28' high on each side. The existing lighting was 277V 400W MH fixtuers with alum reflectors. There were 5 fixtures per aisle and the ft candles were about 7 average with dark areas between fixtures registering 2 and the bright areas registering 12. The top 4' of the shelving was dark the whole length. The T5 fixtures were 8' long with 4 lamps and polished reflectors. I replaced the MH fixtures 1 for 1 with the T5s. What an unbeliveable difference! ft candles average 22 with the darkest areas 20 and the brightest at 24. Even lighting from top to bottom of shelving. Here's the kicker; the MH fixtures draw 460W and the T5s draw 234W. 3x the light for 1/2 the electricity! The T5 lamps do get toasty but this is a climate controlled building kept at a constant 74 degrees so the lighting rep says it isn't a concern. The warranty is 5yrs ballast and 5yrs lamp. I did this 50k sq.ft. area first and they are happy. I have 150k sq.ft. to go. The fixtures on each end of the aisles stay on all of the time and the ones in between have bisymetrical motion sensors with a 5 minute delay so the energy savings will be even greater over MH. The ballasts are program start so switching isn't supposed to shorten their lifespan. This was my first experience with T5 HO fixtures and I haven't read too much about them on the forum so I just thought I'd share.
i will ditto's John commet with the T-5HO it do kick butt with alot of light and yes it did save alot of engery on this one and right now if i am " hearing " this one is the POCO is setting up a rebate some say 75 buck and some saying 100 buck rebate for high bay lumiaires.
i did put few on for demo wow you should see the comuster reaction they just about drop the jaw to see how this flourscent lumiaire do kick out that much light level.
i have few orders line up but have to wait for poco to catch up with rebate it going like nuts here now with higher cost of electric rate[s] they will keep going up anyway
they start pretty fast as well but work pretty good in very cool spot but just take a min or two get warm up after that it work fine and they have instast restrike so i dont have to deal with " dirty quatz " bulbs at all
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)
To be fair, both HID lamps and florescent lamps suffer from reduction in efficiency as the lamps age. Comparing _new_ florescent lamps to _old_ HID lamps will bias your results. I still bet you have a win, given the significant results that you've measured.
winnie, T5 lamps only have a reduction in output in the 5-10% range at the end of their life compared to 15-25% for MH. So a T5 near the end of it's life will still out perform a new MH lumen/watt for lumen/watt.
[This message has been edited by Fred (edited 05-08-2006).]
I've installed about 250 of the T5 six lamp fixtures over the past 2 years & I'm really sold on them. As Fred pointed out an additional benefit is that you can do a lot more with occupancy sensors than you can with Metal Halide.
Few things are harder to put up with than the annoyance of a good example.
"You will also lose some light when those silver reflectors start to haze over."
No more loss than when a glass optic gets dusty or a spun alum reflector gets dull or dusty from static. I've seen T8 fixtures with the polished reflectors that have bee up for 5 years and they don't look too "hazed over". Comparing the pros and cons of MH vs T5 the T5 blows MH away in every catagory. I too was a naysayer until I saw for myself the last 2 weeks.
Lighting Technologies are improving at an exponential rate nowadays, and I encourage anyone - involved with or interested in - Lighting designs + Installations, to check out the new types and fields being produced.