2 tube/3tube/4tube lumens comparison

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stew

Senior Member
the reason for the question is the utility is trying to say that you get as much or more light from a 3 lamp t-8 light as you would from a 4 lamp t-12. I do not see how this is true because you are comparing 4 40 watt tubes with 3 28 or 32 watt tubes. The only difference I see is a reduction in power comsumption. I think that if I have 4 lamp fixtures now I need to stay with 4 lamp fixtures for replacement.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I found this but cannot attest to its' accuracy.

  1. Light Output
  2. Both bulbs put out similar light output although the T8 puts out slightly more light, although the difference is not noticeable to the human eye. According to Philips, a maker of light bulbs and lighting equipment, a T8 bulb produce around 2600 lumens (the unit used to measure light output) while the T12 bulb puts out around 2520 lumens.

    Over time the bulbs begin to lose their intensity and brightness. T8 bulbs have a slower period of decrease, losing only 10 percent of their initial brightness after 7,000 hours of use. In comparison T12 bulbs can lose 20 percent or double the T8 lose after the same number of hours.
 

mcclary's electrical

Senior Member
Location
VA
the reason for the question is the utility is trying to say that you get as much or more light from a 3 lamp t-8 light as you would from a 4 lamp t-12. I do not see how this is true because you are comparing 4 40 watt tubes with 3 28 or 32 watt tubes. The only difference I see is a reduction in power comsumption. I think that if I have 4 lamp fixtures now I need to stay with 4 lamp fixtures for replacement.

The power company is correct, the old magnetic ballast t12 were very wasteful. A electronic ballast t8 will far outperform the old t12's. I have a light meter and have done several different mock comparisons and test. t8's will not disappoint you. Especially if t12's were getting the job done before
 

stew

Senior Member
after looking on the phillips website I find that one of the major differences is in the reflector construction. That is how a 2 tube t8 gives as much or more light than a 4 tube t-12 apparently. Phillips says that the 2 tube t8 is the way to go when replacing the 4 tube old style units. same light and way less energy of course.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
And the LED replacement tubes are probably better than the T-5's. :):)

T5-LED-Replacement-Tubes-High-Voltage-85-265VAC-.jpg
 

raberding

Senior Member
Location
Dayton, OH
Occupation
Consulting Engineer
LEDs

LEDs

LED replacements for linear fluorescents are "not ready for prime time" yet. Too expensive. Not enough output.
Give em a couple years...maybe then.
 

72gs455

Member
Location
Minnesota
I replaced lamps in fixtures and found a drop in foot candles after 100 hours of burn in. We were well above recommended light levels at 62 fc avg and after replacement we have 48.5 fc avg, which is still above IES standards for the area we tested.
Here is what we did...
277v electronic ballasts' (existing)
Removed 32 watt 700 sereis t-8
installed 25 watt 800 series t-8
Extremely happy with results and will start a group relamp of areas to see addition energy savings
 

tshea

Senior Member
Location
Wisconsin
Use a lamp mfr catalog and you can get the lumens per lamp. My bet is the 4-40w T12 are actually 4-34w T12 watt misers.

Ge has new ballasts Ultra MAX that increase the lumens of the lamp! The UltraMax H has a ballast factor of 1.15 which, using the correct lamp will increase lumens to 150% rated!

The lighting game has change immensely in the last 5-10 yrs.

As for T5HO, I have had nothing but bad luck. I prefer T8 at this time. Proven technology.
 

K2X

Senior Member
Location
Colorado Springs
I spent a few years doing 4 lamp t-12's to 2 lamp t-8 conversions with a new reflectors in the Colorado School districts. . We always had 4 or 5 non believers running around with their own light meters but we always got sent on to the next school. Hundreds of schools. More light, better light, (2000 hertz), .5 amps compared to 1.5 amps @ 120 v. It was an easy sell. ..And got rid of their old pcb, (haz waste), ballasts to boot.
 

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
Part of the T8 and T12 differance is that the T8 blocks less light due to being smaller than the T12.
 

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
Some of the light from the top of the lamp bounces back and has to try and travel back through the phospor then through the current stream again; that light is effectivly blocked.
 
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