new t12 bulbs wont fire

[jmaster]

over this summer i finally got around to replacing the 8' t12 tubes in both my fixtures above the work bench. all 4 new ones are in but they wont light up. i get flickering when power goes to them. they were working before, i doubt both the ballasts went out at the same time. (these are old, i'm pretty sure they're the magnetic ones)

the tubes were sylvania eco something or another and they're the right kind with the nipple on the end. tried swapping in all positions, nothing.

 

[jmaster]

would being a different wattage make a difference?

 

[expat]

Have you tried twisting them to see if that makes a difference.

Sometimes the tombstones get bad.

 

[Rand]

Temp might make a difference. Some bulbs dont like 40F in a detached garage for example.

 

[eljefino]

Could be a bad ground. They need grounds, believe it or not. Particularly if the bulb "catches" when you touch the fixture.

 

[George7941]

Originally Posted By: expat
Have you tried twisting them to see if that makes a difference.

Sometimes the tombstones get bad.


I think the OP has the Instant Start tubes with single contacts at the ends, not the double contacts of a Rapid Start.

The Instant Start tubes are particularly sensitive to temperature.

After verifying ground as eljefino mentioned, your next step is to replace the ballasts.

 

[jmaster]

yes they have the single contact ends. i will check the grounds, if the ballasts are bad i'll be retrofitting to led.

thanks!

 

[edhackett]

Originally Posted By: jmaster
yes they have the single contact ends. i will check the grounds, if the ballasts are bad i'll be retrofitting to led.

thanks!


Do the math carefully on the LED retrofit. A T8 LED replacement is only 1700 Lumens vs 2800-3000 for a 4 ft. T8. You will need 40% more bulbs for equal light at 10X the cost and only 12-13% energy savings.

Ed

 

[pkunk]

Check earthled.com. I just replaced 20 - 4ft tubes at $8.99 each and at 18 watts & a brighter light it's quite a savings.
Originally Posted By: edhackett
Originally Posted By: jmaster
yes they have the single contact ends. i will check the grounds, if the ballasts are bad i'll be retrofitting to led.

thanks!


Do the math carefully on the LED retrofit. A T8 LED replacement is only 1700 Lumens vs 2800-3000 for a 4 ft. T8. You will need 40% more bulbs for equal light at 10X the cost and only 12-13% energy savings.

Ed

 

[edhackett]

Originally Posted By: pkunk
Check earthled.com. I just replaced 20 - 4ft tubes at $8.99 each and at 18 watts & a brighter light it's quite a savings.
Originally Posted By: edhackett
Originally Posted By: jmaster
yes they have the single contact ends. i will check the grounds, if the ballasts are bad i'll be retrofitting to led.

thanks!


Do the math carefully on the LED retrofit. A T8 LED replacement is only 1700 Lumens vs 2800-3000 for a 4 ft. T8. You will need 40% more bulbs for equal light at 10X the cost and only 12-13% energy savings.

Ed


As I said, you have to do the math carefully. Carefully includes doing the calculations on an equal lumen basis.

32W 2950 lumen T8 30K hr. life: $3.85/year, $3.00
18W 1800 lumen LED 30K hr. life: $2.17/year, $9.00

20 ea. T8: 59,000 lumens, $60, $77.00/year
33 ea LED: 59,400 lumens, $297, $71.60/year

$237 additional cost of LED. $5.40/year energy savings(7%) = 43.9 year payback. That's twice the life of the bulb.

If you have a need for only a few bulbs and just want "some light" the LED might make sense for you. If you are trying to light to a specific level, say for doing mechanical work or machining, T8 fluorescent are still the cheaper overall way to achieve that specific lighting level.

Ed

 

[jmaster]

i'm still considering a t8 retrofit. i was thinking about making my own led setup to keep cost down. or i can be real cheap and do what this guy did.> youtube.com

the lighting isn't that critical, they hang above the storage area of my shop near the work bench. that being said the other half of the shop is lit with screw base e39 bulbs. i have random 100 and 200 watt incandescent bulbs, 42 watt and crud 12 watt cfls. theres 9 in total. the ceiling is 10'. this is where i do work on my vehicles and more light would be great.

 

[Rand]

leds which are aimed downwards from the bulb seem to be more efficient than florescent bulbs that are omnidirectional.

so on a lumen to lumen basis its not directly comparable.

http://www.hoveyelectric.com/hovey-elect...uorescent-Bulbs

I googled this link for something else but it directly supports

its a decent interesting read.. far beyond led lumen to florescent lumen.

 

[edhackett]

Originally Posted By: Rand
leds which are aimed downwards from the bulb seem to be more efficient than florescent bulbs that are omnidirectional.

so on a lumen to lumen basis its not directly comparable.

http://www.hoveyelectric.com/hovey-elect...uorescent-Bulbs

I googled this link for something else but it directly supports

its a decent interesting read.. far beyond led lumen to florescent lumen.


Thanks for the info on directionality. That will make a difference. The ones I looked at were opaque enough I couldn't see that the LEDs were directional.

One thing your source mentions is that fluorescent bulbs loose light output as they age. They neglected to mention that LEDs also loose output as they age at higher rate and magnitude than an 800 series T8. Just one more thing to take into consideration.

http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/lifetime_white_leds.pdf

Ed

 

[JTK]

Originally Posted By: jmaster
over this summer i finally got around to replacing the 8' t12 tubes in both my fixtures above the work bench. all 4 new ones are in but they wont light up. i get flickering when power goes to them. they were working before, i doubt both the ballasts went out at the same time. (these are old, i'm pretty sure they're the magnetic ones)

the tubes were sylvania eco something or another and they're the right kind with the nipple on the end. tried swapping in all positions, nothing.


I know the 8ft tubes aren't what they used to be. We've got a bunch of 8ft fixtures at work from when the plant was built in 1980. New lamps either fail within weeks, or last a few years.

The only other thing I can think of was I recall the 8ft lamps being available in standard or "HO" for high-output. I don't recall if the ends were different or not. Maybe you've got a miss-match?

 

[George7941]

High Output, Rapid Start, Instant Start all have different contacts at the ends, no way can they be mixed up.

 

[PandaBear]

I just did a direct wire T8 LED retrofit for my old T12 fixture in the kitchen. Talking about the difference in brightness!

In theory the T12 4' would be brighter by 50%, but after a few (likely 6-8) years of use vs the T12's directional tube, I can honestly say the LED is at least 50% brighter. A lot of work though, so I'd say if you do it for the office it is not worth the labor, but for a home project it is definitely direct wire / ballast bypass all the way.

 

[mjoekingz28]

You also may wish to study the light quality. CRI, K temperature, and penetration. And the sound they make(ballasts buzzing/humming) how often you turn them on/off, run time........


As for the problem, did the OP put the old bulbs back in place since I thnk they were 'known working'?