That last line off of the pcb should read 94V-0, and not 9rV-0.

Ed

Wouldn't it be easier just to use T8s? You can get virtually the same light intensity from standard T8 tubes as from overdriven T12s, since you can pack the smaller tubes closer together. And you'll use much less electricity, run cooler, the tubes will last longer, and you don't have to worry about rewiring ballasts and whether the ballast is even overdrivable.

Thanks for the reply, shrubs_n_bulbs. Well, after going through the effort to figure out what I needed, needed to do, and the best course of attempting it...I started stumbling upon the excess heat issue regarding overdriving and seedlings. Seems to me that the basic undriven 40w T12 lamp fixture would probably do what I need it to do...get some tomato, broccoli, etc., seedlings ready for transplanting. But, if brighter is better...

The idea of using mltiple T8's sounds good, but is there a readymade (fairly inexpensive) multiple (more than two tube) fixture for T8's or do I need to get the dremel out and start assaulting a shoplight? The fixtures I've seen that are stated as being ok for T8's allow only two tubes and they're also for T12's so there's no spacing savings...I might as well use T12's. I did a short search and found a 3-tube T8 fixture on eBay that would run around $90...maybe that's why I was looking at the overdriven $20 T12 setup???? I'd really like a cooler running setup, but that extra $70 hurts. Got any suggestions for me...I'm definitely open for them! :)

Thanks,
Ed

My opinion is that the readymade fluorescent fittings are not that useful as plant lights. They have silly things like diffusers or baffles that we don't want, and other than that are just a pretty surround for the wiring. They may or may not have a useful reflector but you'll certainly want a larger reflector anyway or a white covering around the tubes, and possibly completely around the plants.

Look for a high frequency electronic ballast that will drive the number of tubes you want. They are readily available for up to four tubes in the four-foot length, and a four-tube ballast costs little more than a single tube one. Here's an example for $25.

Get some end caps and a few dozen feet of wire and you have a lighting system.

Oh, you'll need some tubes too :) F32T8 tubes are a couple of dollars each or less for the 20,000 hours 3,000-ish lumen variety. Four foot 40W tubes would be nice but are near impossible to find. In the UK we have standadised on 36W T8s which are nice with 3,300+ lumens.

Ed,

"The idea of using multiple T8's sounds good, but is there a readymade (fairly inexpensive) multiple (more than two tube) fixture for T8's or do I need to get the dremel out and start assaulting a shoplight?"

No need to assault the shoplights. Just hang them side-by-side. Home Depot's Commercial Electric 732-334 ShopLights take two T8 or T12 bulbs and are only 5 inches wide, so you can easily get three of them over an 18-inch-deep shelf or four of them over a 24-inch shelf. The 732-334 ShopLights cost only about $8 each. Philips cool white T8 bulbs cost $2 each. That lets you get a lot of light for a reasonable investment.

Since overdriving them gives 50% more light, that is the equivalent of 9 T8 bulbs over an 18-inch shelf or 12 T8 bulbs over a 24-inch shelf. That's plenty of light for growing healthy stocky seedlings to a reasonably large size for setting out. And that's much more light then you get from expensive commercial plant stands. Here in our short Maine growing season I have been setting out pepper plants with sizable peppers already set on them.

If you don't want to cannabilize the shoplights for extra ballasts, you can purchase the SL15T ballasts separately at the Sunpark Electronics online store for $6.50 each. That's cheaper than paying $8 for a shoplight to cannabilize for the ballast.

"The fixtures I've seen that are stated as being ok for T8's allow only two tubes and they're also for T12's so there's no spacing savings...I might as well use T12's."

The 40-watt T12's aren't as efficient as the 32-watt T8's, so the T8's put out less heat for the same amount of light. The overdriven T8s are warmer to the touch than the normally driven ones, but still not hot. As long as you maintain at least an inch or two clearance between the bulbs and your plants, heat from overdriven lighting hasn't been a problem for me.

MM

Howdy MM and shurbs. I checked the HD in Montgomery and didn't see the suggested shoplights. The ones HD had in the $8 range specifically stated they had magnetic ballasts. That's why I opted for the $8 Wallyworld ones.

I'm thinking of setting up two fixtures. I've got an old home built stand that was designed for two fixtures hanging side-by-side. If I'm figuring it right, if I overdrive the fixtures I should be able to roughly attain a 6-tube illumination for each shelf (using to fixtures per shelf).

As for ordering the Sunpark ballasts, if the Wallyworld ones will work it's probably about as cheap to use them (figuring shipping vs. tax, etc.). I think I'll go ahead with the Wallyworld fixtures and see how they work. That would use both "proprietory" ballast end caps. Once I get that fixture going I'll have a metal fixture and two "non-ballasted" end caps that in conjunction with the Sunpark ballasts will build another OD fixture. Being as I've got a couple of older, magnetic ballasted fixtures out in the shed I might go ahead and order extra Sunpark's when I order.

Thanks for the info regarding the heat aspect of the T8's. That helps, especially coming from someone up north that seriously relies on the lights. I guess I when looking a the wattage rating of the bulbs I was stuck in the incandescent mentality of higher wattage being brighter. I guess the form-factor (T8 being skinnier than T12) somehow allows the T8 to be as bright but use fewer watts????

Ed

Ed,

It's not just the form factor that makes T8's more efficient than T12s. It's a much more modern design, by many decades. And the T8s contain significantly less mercury.

MM

The "less mercury" part is all I need to know to persuade me to go the T8 route.

Sometimes progress in technology actually ends up being good, eh? :)

Ed

What MM says is partially true. It is possible to find T12 tubes with virtually the same performance as the best T8s (and equally possible to find terrible T8s). But in my experience top class T12s are not easy to find, suitable electronic ballasts are also not the easiest to find, they may be more expensive since they are not such a mainstream item as the T8s now, and they will always suffer as a plant light from being larger than the T8s. So there just isn't a reason to buy them any more. We may be saying the same about T8s one day if T5 technology ever becomes widespread enough that the price drops to below T8 levels.

Ok, I'm going with the T8's...seems they'll be the "standard" before long. :)

In case anybody's interested here is the information from the box the shop lights came in:

Brand: Lights of America
Model: 8045 E (same as on ballast covering)
Description on box: Shop Light - Electronic - White Finish

Soon as I get the time I'm going to go ahead and OD one fixture and see how/if the ballast/tube works. If all goes well I'll add the ballast from the other fixture for the second tube. :)

Ed

Well, I hacked the LOA shoplights and the resulting OD'd shoplight appears to be working fine. I don't have a regular light to do a side-by-side comparison with, but the light definitely appears brighter. Before I set up the growing station I'll be hacking a couple of more lights so before I hack them I'll compare the OD'd one to a non-OD'd one.

The T8 Phillips Deluxe Daylight tubes heat up a bit more than I expected but hopefully not so much to be a problem.

Now on to the chore of making room somewhere to set up the light and germination trays (will probably be more difficult than modifying the shoplight(grin)).

Ed

I have a few lights with that ballast that says "8045E Series/8055 Series" ... One fixture I cut in half and made an overdriven 2' fixture ... and a couple others I cut down to make 3' fixtures without any rewiring ... mine have worked just fine.

Just to clarify what I did on OD'ing the LOA shoplights...

1. Remove ballast ends from two shoplights and the non-ballasted receptacle end from the shoplight fixture that will house the OD'd lighting.

2. Took a ballast and cut a red and black wire from one side of the ballast and spliced these into the other red and black...red to red and black to black. This was repeated on the other ballast.

(at this point I'm working with two "ballasted" end caps...the regular, non-ballasted end caps are not used.)

3. Took long wires from a ballast going to the other end of the light, splicing the yellow and red wires together. This spliced wire connected to one pin of the opposing receptacle. The single black wire connected to the other pin. This created one overdriven lamp. Repeating this procedure gives you a twin-tube, OD'd fixture with a ballasted end cap at each end.

4. I did not splice the power cords, but simply have both power cords still attached to the end caps.

FWIW,
Ed

I overdrove one of these 8045/8055 models last night and it worked great. In case anyone is confused by the models at Walmart let me explain.

$8 > 8045 E - White finish without pull chain switch
$10 > 8055 - White finish with pull chain switch
$15 > 8055 SS - Silver finish (called "stainless") with switch

They all have the same ballast. An 8055 ballast is just a black 8045 ballast with a switch wired to it. You can wire a switch to the 8045 as well, the same holes exist to solder into.

Here's the really weird thing, when I overdrove the lights I got 100% more power.

T8 (32w) bulb - 37 watts into ballast normally (1 bulb), 59 watts overdriven, 100% brighter

T12 (34w) bulb - 34 watts into ballast normally (1 bulb), 54 watts overdriven, 100% brighter

The brightness measurements were taken against an 18% grey card that was in a fixed position with 3 different digital cameras. Two of the cameras flickered back to 2/3rds of a stop brighter so the actual brightness difference may only be 85% or so, as the resolution of the cameras is only 1/6th of a stop.

Jason

On one of my lights I rewired the one ballast to overdrive one lamp, but then instead of driving a 4' lamp I drove two 2' lamps in series (cutting the fixture in half and making a 2' overdriven shop light). I used the more expensive "stainless steel finish" lights with the pull chain switch. I wasn't sure what light to get, and I was going to get the cheaper white ones, but the box seemed to weigh twice as much. If somebody is going to cut a reflector down and make a light shorter than 4', the "stainless steel finish" light might be thinner metal and easier to cut.

Well I guess I need a correction.

I was working with the guy at Walmart to try to figure out what the difference between the $8 8045E lamp and the $10 8055 lamp were and on the unit we opened there was no switch like the photo of dirt tracker's above. However, I bought 3 of them the other day and they all had switches.

One other thing to note. I found a Walmart locally that sells the 8045E for $10 instead of $8. I asked them why it was more and they said they get that question a lot, and that each Walmart can charge what they want. I don't know, it seems like they may be phasing out the no switch option and are charging more. Not sure.

Jason

Jason: It wouldn't suprise me at all that Wallyworld would stick a 10-cent switch on the same lamp and charge $2 more...the American way.(groan) Interesting, though, that the two pcb's are a different color.

Mikeybob: Would the end results have been the same if you had just cut the fixture down to size for the 2' tubes and left the ballast/end-caps wired as they were?

Ed

It seems to me like one of the lights at Lowes said on the box that it was for T12 lamps and another said that it was for T12 & T8 ...

I believe that someone said they cut a light in half and made a 2' fixture without rewiring, and someone else said that it would be brighter if it was rewired.

Many (most?) electronic ballasts will correctly operate fluorescent tubes in many different lengths, therefore it wouldn't be surprising for a 32W ballast to operate a 18W tube at normal brightness. It sounds pretty "smart" but most T8 tubes run on exactly the same current (265mA) and the ballast must regulate this current over a wide range of voltages even for a single 4' tube. Not a big step to build it to regulate exactly the same current over a slightly wider range of voltages and operate many different tube lengths.

There is a slight wrinkle when it comes to running T8 or T12 tubes. T12 (normal output) tubes throughout the world run on 430mA, while most T8 tubes in North America run on 265mA. Therefore many ballasts will not correctly operate the two types of tube, or they may normally operate a T12 and overdrive a T8. In Europe, T8 tubes also run on 430mA and these tubes can also sometimes be found in the US. Any T8 marked as 36W will be a 430mA tube, whereas the standard 32W T8 runs at 265mA. Confused yet?

Just for completeness, there are T8 HO tubes, rarely seen that run at 380mA typically in a 44W power. T12 HO tubes run at 800mA and 60W in a 4' length. T12 VHO tubes run at 1500mA and 116W at 4' long but usually supplied as longer tubes. T5 tubes run at 460mA and are often called High Output (HO) but that is somewhat meaningless since there is only one kind.

SnB,

Thanks for the good info.

MM

Here is a schematic of the ballast under discussion.
The JPEG resolution gets squashed by the host site
so if someone offers a better home for the document
I'll be happy to copy the JPEG/PDF there.

Here is a link that might be useful: {{gwi:1030211}}