Test: overdriving 48" T8 tubes for 2x or more light output

[rehabkicksass]

This is popular with aquarium people. Apparently all you have to do is re-wire a 2-tube standard T8 shop light with a 4-tube T8 electronic ballast (or stick another 2-tube ballast into a 2-tube fixture) and the result is amplified light output at the same color temp, at the cost of shorter tube life and a little extra heat.

Basically, two 2-tube ballasts run one tube each or a 4-tube ballast runs 2 tubes instead of 4. They actually use less amperage to run brighter lights, from what I read. I'm getting a Kill-A-Watt soon to test with.

I bought a new T8 fixture($11, Wal-Mart), 2700lm @ 6500k tubes($8, Lowes) and a new 4-tube ballast($17, Home Depot) yesterday. I have a digital light meter. Will report back on before and after numbers soon.

If this works I can pump over 10k lumens @ 6500k out of 2 48" tubes at a lower current draw than 2 standard tubes in a single fixture for a grand total of $36 invested.

 

[rehabkicksass]

It works great.

New fixture with 6500k 32W tubes: as advertised, 2700 lm each. 70 degree temps @ 15 minutes run-time with analog thermometer at 2" from tubes.

New fixture, rewired with 4-tube ballast and same tubes: 3800 lm each. 80 degree temps, same thermometer, same time, same place.

Before: 5400 lumens combined.
After: 7600 lumens combined.

That's a 2200 lumen gain from an $11 48" light for an additional $17. :D

 

[LiquidSkyDreams]

i wonder if this shortens the life span of the lamp

 

[seebobsled]

LiquidSkyDreams:

"and the result is amplified light output at the same color temp, at the cost of shorter tube life and a little extra heat."

Great post rehabkicksass

That is what I do for veg too!! And I have diy 6 light with 2 t8 3500k bulbs
overdrive and 4 t8 6500k normal. That is 2, 4 lamp ballasts,one for 4 and one for 2 lights I did this to balance the spectrum and lumen output. The 3500k's have a lower lumen rating. I have the same bulbs going for 3 or so years so not bad for life but heat it does add as said, plus 10 or so degrees. This is a great t5 replacement on the cheap for bulb price with great results.

The secret to bulb life is to burn in your new bulb 12 to 24 hours uninterrupted the first time on min. I did t8 retrofits all over like Sears,Macy's, office and school buildings. We always left the lights on after we finished the job and told to leave on for 24 hours. I had only a few bulbs fail in 4 to 5 years installing in the 90's when t8's went popular. Also If bulb appears like smoke streams floating in the bulb take out and shake the gas in bulb and reinstall it to get the best burn in.

If you go camping, think of changing the mantel on the lantern. The life is impacted by the way it burns in. ( FYI, match light till all white
no lighters!! it blows the filament apart after it lights)

 

[FatMarty]

This works great.
I'm getting @ 22,000 - 24,000 lumens from 6 T8's overdriven 2x.
The 'daylight' 6500k tubes really glow using this method while the 'soft white' 3000k tubes don't get so blinding.

I used a 'high bay' 6 lamp fixture that I got at Home Depot for $85. It has a 95% reflective aluminum reflector that directs most of the light downward even though they have vents behind the bulds to aid cooling. Turns out these vents are perfect for the extra heat overdriving tubes creates. It's made by Lithonia Lighting and I only see it sold at Home Depot when I google it online.

What I did isn't exactly cheap.
With bulbs, and 3 new ballasts at $20 apiece, it cost just about double the original $85 to $170 plus taxes.
I think this is cost effective over a T5 8 lamp unit rated at the same or lower lumen output. But mostly I went this way because T8 tubes run a whole lot cooler than T5 tubes and even tubes that are overdriven 2x don't require much air movement to get a year or more off a set of tubes.
At @$8 for a T8 two-lamp package it is no big deal to swap them occassionally.

The hardest part of doing this is working with the fluorescent lamp sockets.
Not many know how to get the wires in and out of them and you need to know whether thay are "shunted" or not to properly wire your fixture.

Here's a couple images showing my Home Depot fixture retrofitted:

First image shows where you take out one of 4 sheet metal screws that holds the reflector assembly on. (Helps to know how to take apart to save time and stress).

Once reflector is off the internal wiring is exposed in the fixture and you can see here where I used "Ideal" snap connectors that are UL listed/approved for our needs to lengthen and connect primary, secondary, and line wiring in second image.

Third image shows the 3 new ballasts mounted inside the fixture under test, (without reflector assembly). Notice how the wires are positioned away from direct contact with ballast cases and the ballasts are clearly marked as OD wiring. I am religious about safety so I can sleep at night.

 

[FatMarty]

LiquidSkyDreams:

"and the result is amplified light output at the same color temp, at the cost of shorter tube life and a little extra heat."

Great post rehabkicksass

That is what I do for veg too!! And I have diy 6 light with 2 t8 3500k bulbs
overdrive and 4 t8 6500k normal. That is 2, 4 lamp ballasts,one for 4 and one for 2 lights I did this to balance the spectrum and lumen output. The 3500k's have a lower lumen rating. I have the same bulbs going for 3 or so years so not bad for life but heat it does add as said, plus 10 or so degrees. This is a great t5 replacement on the cheap for bulb price with great results.

The secret to bulb life is to burn in your new bulb 12 to 24 hours uninterrupted the first time on min. I did t8 retrofits all over like Sears,Macy's, office and school buildings. We always left the lights on after we finished the job and told to leave on for 24 hours. I had only a few bulbs fail in 4 to 5 years installing in the 90's when t8's went popular. Also If bulb appears like smoke streams floating in the bulb take out and shake the gas in bulb and reinstall it to get the best burn in.

If you go camping, think of changing the mantel on the lantern. The life is impacted by the way it burns in. ( FYI, match light till all white
no lighters!! it blows the filament apart after it lights)

Good post with lots of info man - Thanks.
I'm going to try the burn-in period next time I swap bulbs.

 

[FatMarty]

Here's some more info on working with the sockets and wiring it all up.

First 4 images show how to modify the lamp sockets that come with the Lithonia model I used; you could just use new ones if you can find standarnd medium bi-pin 'snap-in' type holders rated for 600 vac or more. I couldn't find any local quick; so I modified mine as shown. Just be careful prying the plastic pieces apart from the locked position and it's pretty basic stuff.

If you have the older sockets with what appears to be a staple holding a piece of cardboard on the back of it: it is what it looks like and can be lifted out with a hacksaw blade or similar inserted under the staple to pry it up. Wires will fall out of socket once it's apart. You can remove wires from unopened sockets quite easy by inserting a stripped end of solid wire into the tip of the slot the 'held' wire is located while gently tugging held wire.

Last image is a diagram showing how to wire ballast I found on google.

Remember this diagram is for "Instant-Start" ELECTRONIC ballast.
Magnetic, (old style), ballasts can not be overdriven. "Rapid-Start" electronic ballasts use a different wiring configuration for OD; so diagram is no good for those either.

 

[seebobsled]

yes the lamp holders in last pic can get at Graingers .com and are alot easier to work with. They come in different heights to fit all fixtures. Hey pay it forward!

 

[FatMarty]

yes the lamp holders in last pic can get at Graingers .com and are alot easier to work with. They come in different heights to fit all fixtures. Hey pay it forward!

Cool deal seebobsled.
This fixture uses the standard profile medium bi-pin models.
I measured about 7/8" to 15/16" height to center of pins from mount hardware.

 

[rehabkicksass]

Thanks for the replies, everyone. My OD lights are still running just fine!

A quick reading of my OD 2-tube T8 with 3000k tubes in it shows 4000+ lm each. I have achieved 2000 lumens at the floor with the room empty and the lights at 32".

Current flower setup is 3 overhead 2-tube T8 fixtures (one overdriven) with 4 3000k tubes and 2 6500k tubes. 8x 26W 2700k CFL's (4x per side) in y-splitter config hanging on each side. 2x 80mm computer fans, one large dual window fan blowing at floor level, all vented to a 5" fan in the attic.

My next project is adding over 350 5mm LED's in 2 spectrum colors. They'll be configured in a 2" strip to the side of the overheads on adjustable brackets. I discovered that LED third brake lights at the junkyard are effing CHEAP and run on 12 volts. Ford Explorer 3rd lights have 620nm red LED's, Chevy Venture and Astro 3rd lights have 660nm LED's. I'm using 11 of them to make a Fire Stick! I'm not hoping for much, but extra red light can't hurt when flowering! I'm also adding two 120mm fans (39 cfm) at tube level to help cool the reflectors and tubes.

This is all homebuilt because I'm unemployed, what I'm using is what I had on hand and just growing for myself. First real grow, doing beautiful so far. It's very annoying, I have to keep raising the damn overheads!

 

[Iwannagrow]

To Rehabkicksass

I read your post and am considering a grow with the new Litro lights, but would like to supplement them with a more red spectrum T8 light. Would you consider guiding me through the conversion techniques as the lighting materials you used are readily available to me. Thank you for any assistance you can render. For what it's worth, I am a retired hippie from Williams and Takilma Oregon. Thanks.

 

[rehabkicksass]

This video shows how to combine 2 $10 fixtures to produce a single 2-tube overdriven unit. I wouldn't really put much stock in his estimate of "twice as much light" without seeing a light meter reading, though. - http://www.youtube.com/watch?v=WJncJmkQPtM

For more info Google "overdriving fluorescent tubes". That's where I got my info.

 

[rehabkicksass]

New setup: 8-tube T5HO grow light plus a two-tube overdriven T8 fixture. Plants on 3rd week flower and looking great. Buds everywhere! Still working on the LED idea, went and got another ten LED strips from the junkyard the other day for $10. Tested each for output and brightness, choosing only the brightest ones. I've gotta de-solder some things and solder them back together with a power supply but it will work out soon.

 

[rehabkicksass]

Oh, and FYI: I got a 2100 lumen total increase at an expense of 26 watts extra and a negligible increase in temps. The fixture now uses 91 watts as opposed to a standard use of 65 watts. Temps increased by 10 degrees F at the tubes, room temps might have gone up by one or two degrees overall but nothing extreme. (5' x 2' x 7' room)

 

[orbad]

I converted a 2-bulb T12 to a 4 bulb T8 ballast for a buddy tonight and it works great. Quite a bit brighter.