Fluorescent Lamp Sockets for Exposure Box

I'm in the process of putting together an exposure box for contact printing and am a little confused on the sockets. The lamps will be F20T12BL, 24" long (because of limited counter space) and will have medium bi-pin connectors. In shopping, virtually all of the lamp holders (sockets) I've seen have grooves which are designed to mate with a stamped or punched rectangular opening in 22ga (or so) sheet metal. I'm not set up to do sheet metal work. What I'd like to do is mount the sockets directly to the plywood from which the box is constructed. The standard sockets have a single screw hole, but it doesn't look very secure.

Does anyone have any suggestions?

Thanks,
Will

Will, at work right now but think I found a web site that has some that can be screw mounted. Update when I get home. Good question because the one I built was using a shop type single light, harder to keep the lights closer.

photomc said:

Will, at work right now but think I found a web site that has some that can be screw mounted. Update when I get home. Good question because the one I built was using a shop type single light, harder to keep the lights closer.

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Will, as promised.. http://doityourself.com/store/fluorescentfixturepartsandpan.htm

Keep posted on your light source. The first one I did is a proto type for the next one. Also, I could not find electronic ballast for the F20T12 bulbs, so if you do let me know.

Will,

The sockets can be screwed on. I've made 3 12 tube units with sockets that are srewed on. The sockets are 1-3/4 inch OC which means the tube gap is very tight, but that also means the illumination is very even.

Don Bryant

There is only one screw per socket, so theoretically the wear and tear fairy could loosen that screw enough to turn in your box when replacing bulbs. I solved this (I think - mine is less than a year old) by backing up each socket with a strip of wood. This traps the base so it can't swivel. I used a #8 x 3/4 round headed wood screw into fir, and put a bit of Elmer's glue on the base for good measure. The cutout for the screw is shouldered in the plastic and the final result seems very stable.

I looked for a ballast that would support 4 bulbs, but did not find any. Therefore I have 6 ballasts for 12 bulbs. It was painful at the checkout counter, but made wiring a snap.

I spaced the C/L of the sockets 1-1/2 in. apart. This means no finger room between bulbs, and I have to remove #s 12, 11, 10, and 9 to get to #8. This gives a nice, even illumination and relatively short exposures when 4 in. away from the print frame.

Mike,

Thanks for the link. Those look almost identical to the ones I found at Home Depot. They do have one hole for screw mounting, but it seemed a little inadequate. Probably it will work just fine, though, as Don indicates. And their price certainly looks favorable.

I have found a link for electronic ballasts at American Light. They also have a 3-bulb model for around $28.00 which the salesperson told me about, but which I did not find listed on the page. It may be more economical depending upon your application. I don't see any reason not to use the 3-bulb ballasts and will probably order those myself.

-Will

photomc said:

...could not find electronic ballast for the F20T12 bulbs, so if you do let me know.

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Will, Thanks for the info on the ballast. Had looked there, but did not consider calling because nothing was listed. Don't see any reason a 3 bulb would not work. BTW, mis-read your original post, thought you needed to find a screw in lampholder, sorry. I agree that it does not seem all that stable, wonder if a thin strip of wood or other support on each side of the holder would help. Interested to here what others have done.

photomc said:

Will, Thanks for the info on the ballast. Had looked there, but did not consider calling because nothing was listed. Don't see any reason a 3 bulb would not work. BTW, mis-read your original post, thought you needed to find a screw in lampholder, sorry. I agree that it does not seem all that stable, wonder if a thin strip of wood or other support on each side of the holder would help. Interested to here what others have done.

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The screw mounted sockets are very stable, I place a large washer under each socket. On each side of the of the surface the sockets are mounted to, I've cut a large slot, that allows the sockets to be easily moved in one direction or the other to make socket positioning easy, accurate, and provides simple routing of the wires going to each of the sockets.

Don Bryant

Mike,

I think between Glenn's and Don's suggestions I now feel reassured that the readily available bi-pin holders will work fine, anchored as they've suggested. I'll go ahead with what I've got on hand and probably order the rest from the link you provided.

Now that I'm home and have my notes, the ballast for 2 bulbs is the REL2S40SC which at this writing has a price of $22.62. The 3-bulb ballast is REL3S40SC which is priced at 27.62. American Light has several offices apparently. The one I called is in Dallas at (214) 217-0190.

I appreciate everyone's input. As I progress with this, I may have more questions. It will be nice to be able to finally get around to printing!

-Will

photomc said:

Had looked there, but did not consider calling because nothing was listed.

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Here's the ballast that I am using in mine. Five lights to one ballast sure holds the weight down as well as making the building easier.

Fulham workhorse ballasts

Hope this may help.

Kind Regards,