# changed 2k f32t8 lamps to the energy saving 25 watt lamps



## erics37 (May 7, 2009)

An older school setting is nice for that sort of stuff, minimal starts and reasonably long run/burn-in times. Plus it's indoors. It's an ideal setting for those lamps, but if you've got all sorts of different kinds of ballasts, then all bets are off. I'd sell them up on fixture upgrade kits rather than just relamping. You might get some warranty callbacks a few months down the road.


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## MDShunk (Jan 7, 2007)

You did all 2,000 lamps, huh? Sorry about that. I meant to send you to the building next door. Can you switch them back quick?


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## knowshorts (Jan 9, 2009)

Are all T8 ballasts even rated for 25 watts? And no ghostbuster effect?


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## mbednarik (Oct 10, 2011)

So far no problems. They are all rated for F25T8, but really don't say for a 25w F32T8 replacement. I told them if there are ballast issues that it would be extra to swap em out, but so far so good.


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## knowshorts (Jan 9, 2009)

Mayby I'm not quite awake, but isn't an f25t8 a 3' lamp? Interesting thread, keep us informed.


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## HARRY304E (Sep 15, 2010)

knowshorts said:


> Mayby I'm not quite awake, but isn't an f25t8 a 3' lamp? Interesting thread, keep us informed.


Yes they are but they do make a 4' t-8 that is 25 watts it is Lamp Designation F32T8/25W/SPX*/ECO, 

http://www.grainger.com/Grainger/GE-LIGHTING-Fluorescent-Lamp-2ETR8?Pid=search


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## knowshorts (Jan 9, 2009)

I am awake now. I know about the 25 watt 4' lamps. I've heard the sales guys claiming they save 22%. But, I always wondered if they would truly work properly on a ballast that doesn't say 25 watts. I've seen ballasts show a wattage column and I've seen them without. I've also heard 25 watt lamps also cause the ghostbuster effect unless properly mated with anti-striation (sp?) ballasts.


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## RePhase277 (Feb 5, 2008)

Once you close the lens, you can't see the ghost buster effect:laughing:


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## Cletis (Aug 20, 2010)

*HZ*



knowshorts said:


> I am awake now. I know about the 25 watt 4' lamps. I've heard the sales guys claiming they save 22%. But, I always wondered if they would truly work properly on a ballast that doesn't say 25 watts. I've seen ballasts show a wattage column and I've seen them without. I've also heard 25 watt lamps also cause the ghostbuster effect unless properly mated with anti-striation (sp?) ballasts.


Thats what happens when you use 60Hz ballast. I only use 10kHZ ballast. No appearent flickering to the eye


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## noarcflash (Sep 14, 2011)

Did you amp one ballast before and after? I'd be curious to know.
How is the lighting ?
Is the less wattage noticeable?


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## Electric_Light (Apr 6, 2010)

F25T8 is a 3' lamp. 

F32T8/25W is a 48" T8 with predominantly Krypton fill with a lower discharge voltage which operates at a lower power on a constant current source. 



Cletis said:


> Thats what happens when you use 60Hz ballast. I only use 10kHZ ballast. No appearent flickering to the eye


No, krypton filled lamps like 48" T8 25W is susceptible to striation effect, which looks like spiraling effect. Ballasts designed for Energy Saver lamps have a frequency modulation circuit that mitigates striation.


As for energy savings, it depends on each ballast design. In response to reduced operating voltage, some ballast will increase current, thus reducing savings. 

Thermal characteristics are also different from normal F32T8. In my experience, 48" T8 25W lamps do not come down in power as much as F32T8s as the lamps warm up inside the fixture. 

If the electronic ballasts are fairly new, the power factor is close to unity, so, measured voltage x measured current (you need to use a clamp meter that can accurately measure down to 0.1A at below 30A, many clamp meters rated to 200A are not accurate in this range) gives a fairly accurate wattage. Testing on one ballast won't give a good idea here since you mentioned there are several different ballasts. 

Allow the existing setup to run for several hours then measure at the switch.

Change lamps, then measure after they've be on long enough to fully warm up. Measure. 

The difference between the two is the real world saving.


Although the 25W 48" lamps have a lower discharge voltage once started, the voltage needed to strike is higher. So, older rapidstart Motorola ballast with low OCV may not start reliably. Lamps are also not guaranteed to start reliably below 60F. 

Electrically, the lamps behave similar to 3' F25T8 once started. So, some old ballasts that is rated only for F32T8 and not rated for F25T8 may fail.


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## wanderer (Jul 19, 2011)

Electric_Light said:


> F25T8 is a 3' lamp.
> 
> F32T8/25W is a 48" T8 with predominantly Krypton fill with a lower discharge voltage which operates at a lower power on a constant current source.
> 
> ...


Does this apply to the 48" 28W lamps, as well?


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## Cletis (Aug 20, 2010)

*Ok*

code blue. 

In my humble opinion it is much better just to use a full spectrum 32W t-8 with a high grade phosphor (limits light degradation) and underdrive the ballast. it gives you the best light, longest lumen depreciation, and best ROI.


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## Electric_Light (Apr 6, 2010)

Cletis said:


> code blue.
> 
> In my humble opinion it is much better just to use a full spectrum 32W t-8 with a high grade phosphor (limits light degradation) and underdrive the ballast. it gives you the best light, longest lumen depreciation, and best ROI.


The idea behind 25W lamps is to avoid the cost of ballast replacement. 
25W 48" lamps already use the best available phosphor (ADVANTAGE 8xx phosphor). 

25W lamps do reduce the total output compared to 32W lamps. What I'm saying is that the savings is not 25/32 x current power usage, but they do provide reduction in power.


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## Cletis (Aug 20, 2010)

*lights*



Electric_Light said:


> The idea behind 25W lamps is to avoid the cost of ballast replacement.
> 25W 48" lamps already use the best available phosphor (ADVANTAGE 8xx phosphor).
> 
> 25W lamps do reduce the total output compared to 32W lamps. What I'm saying is that the savings is not 25/32 x current power usage, but they do provide reduction in power.


Well. The best formula for me is using t-8 high grade phosphor and beefy cathode tubes (7 yr life) with underdriven ballast (30yr life) with miro 4 relector. I think we get 20-30% more "usable" light using on 2 bulbs per fixture say replacing an old 4 bulb 40W T-12 system. The ROI is pretty good and the 10 yr cost savings is huge


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## Electric_Light (Apr 6, 2010)

wanderer said:


> Does this apply to the 48" 28W lamps, as well?


For the most part yes, but 25W is more likely to give snaking effect and experience starting difficulty. Though it varies from mfr to mfr, dimming is not advisable on 25W lamps. 

They require 600V OCV and >60F ambient for reliable starting, which older Motorola rapid start electronic ballasts do not provide. 25W lamp is more likely to experience starting failure than 30W. 

Ballasts rated for F32T8 only may fail prematurely. Modern ballasts rated for 17, 25 and 32 should be fine and the only concern is snaking effect which is not a safety/reliability issue, but an annoyance. 

Newer programmed rapid start and all instant start ballasts rated for 0*F starting shouldn't have any starting problems. 


48" T8 lamps come in 32, 30, 28 and 25W 
32W is the most common and can be operated on any ballast meant for T8, magnetic and electronic. The 28 and 25W require much higher voltage to ignite and won't start (reliably, if at all) on magnetic.


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## kbsparky (Sep 20, 2007)

knowshorts said:


> Are all T8 ballasts even rated for 25 watts? And no ghostbuster effect?


I have discovered that reversing the bulb usually corrects the "Ghostbuster" effect.


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## Electric_Light (Apr 6, 2010)

Cletis said:


> Well. The best formula for me is using t-8 high grade phosphor and beefy cathode tubes (7 yr life) with underdriven ballast (30yr life) with miro 4 relector. I think we get 20-30% more "usable" light using on 2 bulbs per fixture say replacing an old 4 bulb 40W T-12 system. The ROI is pretty good and the 10 yr cost savings is huge


If the existing system warrants an upgrade, it's a viable option.


25W lamps are costly, but if the area is over-lit by (OSHA requirements) and customer is ok with level getting lowered so long as it meets OSHA reqs, it has a very fast payback.

There is no incremental labor cost if you wait until the scheduled group re-lamp.


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## 3rdgenwireman (Dec 12, 2010)

If you use a 20 gigawatt flux capacitor, it will fix everything.:no:


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