What (if any problems) will happen if a T8 bulbs are used with T5 ballasts?
Can a T8 bulb work with a T5 ballast
ballastfluorescent
Related Solutions
I'm a bit alarmed when I hear you say "capped off my yellow wires". A few ballasts do give that instruction, but not for 2-bulb use. I fear you might be matching up wire colors and not following the schematic on the ballast. Thing is, if the old ballast was instant-start, that will totally backfire. As you can see in these typical schematics, red and blue do quite different things on the two types of ballast. (ignore the LED one).
These schematics are not universal, only common. Yours is on the label on the ballast.
When converting instant-start to rapid-start, the other issue is shorting . The instant-starts only connect 1 wire to each end of the bulb, but it goes to both pins. This is almost always accomplished with a shorting lampholder (tombstone), which accepts one wire and connects it to both pins.
A shorting lampholder will have 2 holes for wires, but that's for daisy-chaining (as in the red wire above), not for 2 separate wires. A non-shorting lampholder intended for rapid-start ballasts will have 4 wire holes, 2 for each pin. The extras are for daisy-chaining, as in the yellow below.
Unless there's a visible wire to remove, there is no way to turn a shorting lampholder into a non-shorting one. You just need to buy replacements. They are fairly standardized, and I buy mine online for about 60 cents a tombstone. I buy only non-shorting types, it's easy enough to convert one into shorting with a wire.
After scratching my head - I decided to pull the tombstones out and inspect the wiring to make sure there was no sneaky connections and also nothing out of the ordinary. The older ballasts (original diagram are Magnetic Ballasts with PCB) the new ballast are electronic. I contacted the manufacturer and they suggested to verify my grounds for the ballast assembly. Since I had several that were fine and all inline - I verified ground from good unit to ground on unit that I was shocked with. Grounds were good.
So upon pulling the tombstones out and checking the wiring - I tugged on each of the wires, one of the wires just slid out of the connection. While it was inserted in the tombstone connection just fine; it just kind of slid out as if the spring clamp had not locked it in. I removed the wire and installed a new wire into the tombstone making sure it clamped down on the wire. After I had done this there was no longer an issue. I assume the wire was close enough to conduct but far enough away to cause the issue.
I do not understand that engineering wise - but maybe it has something to do with RF, High Voltage and an Air gap.
Related Topic
- HPS bulbs and ballast wattage compatibilty vs replacement technologies
- Electrical – what is the likely cause of a single fluorescent tube not working in a light fixture with a ballast that supports two tubes
- T5 bulbs with T8 Ballasts
- Replaced bad ballast and maginfying light still won’t work
- Same-sized alternatives to F14T12 bulb
Best Answer
It won't work right. It will overdrive the tube (or underdrive the tube) and you'd get short tube life. It may flicker horribly. It may not be able to strike.
Basically the same things that will happen if you put T12 tubes in a T8-ballasted fixture.
It's basically a dumb thing to do.
If you got a wrong thing, take it back and get the right thing.
This may not help, but.. You know, if you have a T8 fixture and it uses anything like standard tombstones (lamp sockets), they sell special extension tombstones to fit a T5 bulb. Or if the fixture already has that upgrade, you can roll it back using standard tombstones.
Though the T5 is slightly more efficient, all things being equal.