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#179995 08/08/08 11:29 AM
Joined: Jan 2005
Posts: 61
jkochan Offline OP
Our commercial building of 1001 thousand square feet and about 1100, T-8 three bulb parabolic troffer fixtures is coming up on 10 years old. We have re-bulbed three times and are coming up on the fourth. The existing ballasts are Advance PEL-3P32-RH-TP, 277V, 60Hz, .32A and have been to this point, remarkably dependable. Does anyone have any experience with ballast longevity in the ten year + range ? We have a number of options: 1) Re-bulb as-is and hope that the ballast don’t fail before the next re-bulb. 2) Re-bulb and re-ballast as existing. 3) Retro-fit to 2 bulb T8 conversion with new reflectors and ballasts to eliminate one bulb. Numbers two and three will most likely fall into the capital expense category and there by saving 1100 trips up and down a ladder that option number 1 will involve since we can’t use a lift in most of theses areas. The conversion to T-5 has been ruled out as too expensive. So, in your opinion(s) should we be concerned about the ballasts’ life at this point? Are new ballasts appreciably more efficient that what we have now? Will it be cost effective to replace them all versus an as- they -fail senario? I’m interested in all view points. I’m hearing what appears to be some pretty tall tales from various lighting manufacturers about “energy savings”. In a perfect world, what would our power consumption be on a single three bulb fixture with the ballast listed above, with three 28 watt bulbs running for one hour? Are we consumint 28 watts x 3 for one hour or .32 A for one hour?

Joined: Oct 2006
Posts: 745
The biggest killer of ballasts is failure to relamp immediately upon lamp failure. A good maintenance program will allow you to easily see 20+ years life out of a modern ballast. It's just the same as keeping the oil changed in your car; take care of it and it will take care of you.


"But the guy at Home Depot said it would work."
Joined: Sep 2004
Posts: 68
If you multiply the .32 amps by the 277 volts, it is about 88 watts which is your connected load. (3X28 plus what it takes to run the ballast).

One other possibility is looking at the ballast wiring diagram. Many of the instant start ballasts are designed to run both two or three lamp fixtures. Those ballasts allow you to connect two lamps and cap the third wire with a wire nut. Perhaps many areas of your building especially over furniture cubicles could get by with two lamps.

Also look at corridors and hallways--many buildings have more light than what is required by the code for egress and life safety. Disconnecting and or removing selected fixtures in a large building can save a lot of electricity in just one year's time.

Obviously there may be aesthetic and or work environment issues involved here as well- there are many studies that link loss of worker productivity to lowering lighting levels in the workplace.

Joined: Nov 2005
Posts: 31
Junior Member
I don't believe there is that much saving trying to go down the 28 watt lamps or going to electronic ballasts. You may wish try going to a brighter lamp. the standard t8 stuff is 3500k, try going to 4100k and reducing to two lamps. That should not be problem because the t8's are parallel feed type lamps. If you can reduce one lamp, now that is 32 watts not 6 watts, with that you will see savings. Also try to reduce the hallways to one lamp. Many of the large retailers are do this to reduce energy costs.

Joe Ogle

Joined: Jan 2005
Posts: 5,370
Likes: 1
Cat Servant
For the OP: I've seen plenty of the old-fashioned ballasts last decades - as evidenced by the paint on the fixtures, from tenant changes.
I fully expect your electronic T-8 ballasts to run until the end of the world (in 2012, according to the Mayan calender).

T-8 fixtures seem to operate just fine with fewer lamps than the fixture is intended to have. Indeed, I notice that replacement ballasts are often rated for a variety of bulb combinations. I'd feel comfortable operating them without a bulb in every set of sockets, if the light is too bright for comfort.

I really, really detest poorly lit, cave-like hallways. If you're worried about energy costs, I'd first actually measure, and see what is REALLY running up the power bill. Last Spring I went through this with one plant manager; in the end, the real culprit was one of his production lines.

There IS something to be said for better lighting control .... either multiple light levels, or local lighting control. The old idea of all the lights being controlled by a single switch disgusts me.

I have, in fact, measured considerable energy savings between T-12 and T-8 lighting. A reduction of 30% is not to be ignored. I do not, in most situations, recommend changing from T-8 to T-5.

The T-5 is, however, the cats' meow as a replacement for MH high bay fixtures. If the high bays are HPS ... well, I'll get banned if I say what I think of the designer who put those things indoors.

Finally, as for the practices of major retailers .... I have a ring-side seat to this very debate. "Corporate" wants the lights dimmed .... the store managers do what they can to defy this edict, simply because they can see an immediate, and direct, effect on their sales (and thus their bonus).
I suspect the same can be said for productivity in most places. The nickel you save by reducing the lighting could very well be the most expensive 'savings' you've ever had.

Joined: Jul 2004
Posts: 625
Originally Posted by renosteinke
I really, really detest poorly lit, cave-like hallways.

"Corporate" wants the lights dimmed .... the store managers do what they can to defy this edict, simply because they can see an immediate, and direct, effect on their sales (and thus their bonus).

I suspect the same can be said for productivity in most places. The nickel you save by reducing the lighting could very well be the most expensive 'savings' you've ever had.

I can testify to this first-hand. I can't work at a long-term job in most commercial buildings here in sunny California, because (thanks to Title 24) they're too dark inside. After several weeks, I start to run down, and go into "hibernation", and lose my ability to focus and be effective at my work.

(This, incidentally, is why I'm "SolarPowered"--my body seems to be powered by the sun. cool (And you thought my screenname had something to do with where I get my electricity from-- wink ))

This is why I'm in business for myself, because I need to be able to control my environment so that I get enough sunlight.

Joined: Mar 2007
Posts: 404
One thing I've wondered about the commercial applications, where all lamps are replaced at the same time--what happens to the ones that still work? Do they get recycled with the dead ones? I'd be a willing foster home for some of these lamps, even if it means I have to break out the ladder and change a few more often. It's really no inconvenience to me, since we change the rest of the lighting around every few weeks anyway.

Joined: Jan 2005
Posts: 61
jkochan Offline OP
We used to send all of the removed bulbs for recycling. At this time of yea, we are in a voluntary load shedding schedule with our lighting reduced to 95% of normal levels between the hours of 10 AM and 7 PM, which coincide with our peak demand hours. The rank and file generally like it because it makes it easier to see their computer screens. We supply desk top lights for those who find it too dark. For the most part every body likes it.( the oooh factor) This usually wears off in about 8 weeks and as the day shorten we usually have to adjust the timing on the controllers to compensate. So far I seem to have two different opinions on whether or not removing bulbs from the fixture has a detrimental effect on the lighting ballast. Are there any other opinions on this? I’m about ready to start calling the Mfg’s , but they always tell you what you want to hear (as long as it’s to their benefit).

Joined: Aug 2006
Posts: 3
Junior Member
The ballast label will tell you if removing one lamp is ok. 89VA per ballast is not bad (VA, not w).

You might consider the higher efficiency T8 lamps now available at slightly higher cost. Do the math to see if they really pay in your application.

If your ballasts are doing so well, leave well enough alone.

Joined: Jun 2006
Posts: 613
I have a question about t12 lamps in the US. They are to be unavailable in another year or two which is forcing Canadians to upgrade to t8. Is this also happening on the south side of the border?
Back in the 80s I did a lot of relamping and I'd go and replace all the bulbs in 1 shot as well as remove the third lamp and ballast where installed. We would show big energy savings and everyone patted themselves on the back. Cleaning the fixtures, new slightly brighter lamps at the beginning of their life all looks like the same light levels at 2/3 the cost. Except after 6 or 8 months and winter arriving the light levels would drop below the industrial standard and I would return to reballast 1/2 of the fixtures I just stripped out. Frustrating!!
JDO1942 You mention going from 3500K lamps to 4100k as brighter. Not necessarily so, the K is for Kelvin and it is the color of the light not a measure of the brightness.
You will often see car lamps in the blue range, 6000K I believe, advertised as brighter than the 4200K lamps. They often do appear brighter but measured with a light meter are sometimes less bright. The OSHA people use a light meter not a color meter and even though we perceive bluer light as brighter often the yellower colors are actually brighter.

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