Looking for 4 bank T12 Fluorescent Ballasts

[Matt Irwin]

I've been on the hunt for some 4 ft. 4-lamp T12 electronic ballasts for some custom fluo lights I'm building. Unfortunately, 4 bank T12 ballasts are being phased out in the States and they are really hard to find. Does anyone know of a place in the LA area that has any in stock? These aren't Kino or Magic ballasts, just regular brick ballasts.

 

[before someone brings it up, two 2-bank ballasts won't work because of the way they have to be wired (I'm wiring them to be used with add-a-taps). I spent a few hours with a gaffer trying to make them work, and no dice.]

 

Thanks,

MI

[Phil Rhodes]

Hi,

 

Don't get why 2-lamp ballasts can't work. If you want to run four tubes, what's the problem?

 

I can give you a box with two two-lamp ballasts in it which will work almost identically to a four, although it occurs to me that this might be one of those situations where the different ways flos are run on 110V mains may make my experience different to yours. Electronic ballasts do work the same way, though.

 

Phil

[Chris Keth]

[before someone brings it up, two 2-bank ballasts won't work because of the way they have to be wired (I'm wiring them to be used with add-a-taps). I spent a few hours with a gaffer trying to make them work, and no dice.]

 

Why is that? I see no electrical reason why 2 ballasts couldn't work.

[Matt Irwin]

Why is that? I see no electrical reason why 2 ballasts couldn't work.

Neither did we...

We tried both a magnetic and an electronic and could only get one tube to fire no matter what we did to the wiring. We followed the diagram on the ballast as a guide (like we do with the 4-tube units) and got nothing. We then tried some other combinations, and still nothing.

 

**I realize I should have worded the original post better: We were trying to wire the 2 bank ballast alone, not with two to make a 4 bank. I decided to just look for some more 4 bank ballasts because I need some anyway.**

 

Mind you, we weren't wiring a shoplight fixture-- we were connecting the leads to zip cord and add-a-taps, not exactly the textbook way of doing it. It is also possible that both the ballasts were defective, but it seems like it would be pretty rare to get two unidentical ballasts like that.

 

I would post pics of our wiring, but I'm not at our workspace right now.

 

I can give you a box with two two-lamp ballasts in it which will work almost identically to a four, although it occurs to me that this might be one of those situations where the different ways flos are run on 110V mains may make my experience different to yours.

I don't see how it would be different in 220 land. There are plenty of 4-tube fixtures here that have 2 ballasts.

Although, you made me realize... I should just go buy a fully assembled shoplight, see how it's wired, and check it against ours.

[Phil Rhodes]

Hi,

 

What sort of wiring you use shouldn't make much difference, although trying to put the tubes more than the usual distance from the ballasts can incur some extra radiated interference which could cause consternation with the sound department.

 

Assuming the ballasts are known good, as you say, there's usually a diagram printed on the back which makes it fairly difficult to screw up. You're not trying to wire electronic ballasts with starters or something? If you're not sure about your starters on a magnetic ballasted unit, try replacing them with a momentary switch (or just tap the ends of the wires together, but keep your fingers clear.) With the magnetic ballast, did you get an orange glow at one or both ends of the tube when attempting to start? You can also try placing the tube near a grounded metal object, usually the reflector, which can aid starting by providing a capacitive path to ground.

 

Old-style magnetic ballasts work differently in 110V countries, generally comprising a step-up autotransformer and current-limiting inductor as opposed to just the inductor. The running voltage of a 4-foot tube is generally 80-100V, and 110V mains doesn't provide enough of an overhead to start or run reliably with simple ballasts. This doesn't really apply to electronic ballasts, though.

 

Rapid start ballasts, electronic or magnetic, can have additional issues. More info helpful.

 

Phil

[Matt Irwin]

Assuming the ballasts are known good, as you say, there's usually a diagram printed on the back which makes it fairly difficult to screw up. You're not trying to wire electronic ballasts with starters or something?

The first thing we did was follow the diagram, and only got one tube to fire. No, no starters, just the ballast alone with an ac plug and two add-a-taps.

With the magnetic ballast, did you get an orange glow at one or both ends of the tube when attempting to start?

Not exactly. One of the two tubes would fully fire or none would fire. On the electronic ballast, we got a very dim glow all the way across one tube only.

Rapid start ballasts, electronic or magnetic, can have additional issues.

Both ballasts are Advance brand Rapid Start. What kinds of issues are we talking about?

 

I'm sorry I am unable to be more descriptive. I'll be at the workshop on Friday, so I'll take some pictures and post them here. Thanks for your help, Phil.