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How to make 24' four-tubes fixture?

18 years ago

How to make 24" four-tubes fixture (for T8)? Trying to find cheaper option than ready-made. I'm worried more about mechanical part than electrical, and supplies: what 48" tube holders (they seems to be cheaper) would be suitable to feed 24" tubes. If 2 shoplights have to be connected, what is the good way to do this, including reflectors?

Any advice? Thanks.

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Comments (8)

shrubs_n_bulbs
18 years ago
The holders are just that, holders to position each tube against electrical connectors to the ballast and starter. Very often they include some safety cutout switches or the like, but they might not. The reflector can be anything that sends the light in the direction you want.

I'm not sure what you are trying to achieve with the four foot holders. If you have room for a four foot holder, you should use four foot tubes. You can't mount two two foot tubes in there. You will likely need to change the ballasts to some suitable for your short tubes. Or are you going to cut two feet out of the middle to make a two foot holder?
townhouserOnt
Original Author
18 years ago
2' fluorescent light (I don't know the difference - fixture, light or holder; metal thing with ballast, starter, pins and wires, that holds fluorescent tubes/bulbs?, like sold under names shoplight or under cabinet lighting. Pardon my luck of knowledge) that uses 2 tubes costs CN$80, 4 tubes - above $100. I'm looking for a way to achieve the same result cheaper. The thread below mentiones possibility of making 2' fixture from shoplight (scroll down to post dated Oct 19, 04 at 2:25, Dec 5, 04 at 21:54, and below it).
I only have shelves 27 x 19" (greenhouse shelves), 4' lights are too long. No need in overdriving, just to make short-length lighting tor plants.
I can't find description of mechanical disassembly and modifications, but continue the search. I would like to cut four feet in the middle to make two two-foot holders if I'll know how to make them working again. If possible, tie them together and add common reflector, one power cord instead of two will be better.
Sorry for not being clear.
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townhouserOnt
Original Author
18 years ago
Link is here:

Here is a link that might be useful: I have found the BEST cheap flourescent
shrubs_n_bulbs
18 years ago
You can cut 4' shoplights in half (or take 2' out of the middle) and use them as holders for 2' bulbs. You would probably need to replace the ballast and starter with one for the shorter bulbs.

You can get a 2x24W 24" lamp for under $20, I think that might be a better solution for you. Or you could use a couple of compact fluorescents which can be useful for lighting small areas, maybe even one of the 2-D bulbs.
KayLakeMan
18 years ago
The link is for a well known 'overdriving' experiment and not so much on how to make a 24" light fixture. The process involved using 2 ballasts (one from each fixture) and making a single 2, lamp fixture using a ballast for each of the tubes with a higher 'light' output than a normal 2 lamp fixture...special ballasts required. It also resulted in left over fixtures which some used for other experiments such as cutting down to 24".
If you have not got the extra fixtures to recycle, it is simpler (and likely cheaper) to just buy the 24" fixtures...unless you have an incredibly cheap source for 48" but can only fit 24".
townhouserOnt
Original Author
18 years ago
Canadians and Nort-East of US, where did you saw cheaper 2x24"(or 4x24") FL, that can sent internationally (or are located in Toronto)? My prices are from Ca Tire - CN$80 2x24" and CN$20 shoplight 2x48".
lite
18 years ago
Has anyone tried just cutting down a 4' 2-bulb T8 fixture and using the same electronic balast with 2 2' T8 bulbs? Will this result in "overdrive" similar to the 2-balast/2-bulb systems described for 4' systems? I'm having trouble finding affordable 2' T8 fixtures. 4' fixtures are much more common.
zink
18 years ago
Lite,

I have modified several of 4' shoplights by cutting them down with a Dremel tool. I have made a 36" fixture and several 24" fixtures by cutting them shorter.

It is helpful if you can visualize how the metal end would look if you cut so it can fold back together... just as you would imagine a cardboard box unfolded and folded back together. I have used both rivets and sheet metal screws to refasten the pieces.

If you are making a 36" fixture, you can use two ballasts - one to overdrive each bulb.

If you are making a 24" fixture then you should know this helpful little fact:
You can wire 2-24" 17W lamps, in series, to substitute for a 48" 32w lamp.
--- OR ---
=[17w]==[17w]= is basically the same as =[32w]=

You will get more light by wiring up the modified 24" fixture to overdrive by 2x, using only one ballast and two 24" lamps wired in series. That is as opposed to using the original default wiring scheme, driving each 24" lamp separately in place of each 48" lamp.

I have wired them up both ways. Simply repacing the 48" lamps by the 24" lamps does drive the 24" lamps brighter, but not nearly as bright as wiring the 24" lamps in series and then overdriving by 2x

Good luck.

Zink

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