T12 and T8 fluorescent bulbs intermixed?

[Imthedude]

While looking into replacing a couple of lighting ballast I noticed several of the lights had a
combination of T12 and T8 tubes. Just curious if this is a fairly common practice or not I usually perform new construction work so don't get into the service or retrofit side of this trade very
Often thanks in advance.

 

[sup2]

Lighting mix-up.

Lighting mix-up.

This will only work if the ballasts matches the lamps.:slaphead:

 

[fmtjfw]

The general result of mixing T8 and T12 bulbs on a single ballast is a headache inducing flashing of lights. Indeed putting T12 on T8 ballast or the reverse is generally a really bad idea. I know -- schools are boxes filled with fluorescent lights.

 

[kbsparky]

Usually the result of untrained maintenance personnel replacing burned out or busted bulbs with whatever is found in the closet.

Had one customer complain about pulsating bulbs in one office, and we found exactly that: Mixed bulbs in the same fixture. Once we determined which bulbs should be in there, installing the correct ones solved the problem.

 

[spark master]

It's amazing they didn't make them idiot proof, with a different tomb stone.

 

[kbsparky]

They DID when they invented those T-5's

 

[infinity]

They DID when they invented those T-5's

 

[spark master]

That's only because the lamp ends are physically too small to fit in a T8 tomb stone.

 

[fmtjfw]

That's only because the lamp ends are physically too small to fit in a T8 tomb stone.

Yea, but they could have gone with a single tiny pin that fit in one side of a T12/T8 tombstone.

 

[infinity]

Actually T5 lamps are based on a European metric standard and are not the same lengths as domestic florescent tubes.

 

[TNBaer]

I had a customer complaining about the heat of his T8 Lamps in a low ceilinged office. They kept the lights off it got so hot. I flipped the switch and they seemed awfully bright. Pulled the ballast cover and, sure enough, T12 ballasts.

T12 operates at nearly twice the current of T8, the T8s on those ballasts were being overdriven by a substantial sum and that created all the heat. T12 on a T8 ballast will usually flicker, but you can't tell because T12 flickers no matter what ballast it's on.

 

[kwired]

It's amazing they didn't make them idiot proof, with a different tomb stone.

I think a lot of new T8 fixtures use a shorter height socket and you will not have room to install a T12 lamp, but if you are retrofitting existing T12 fixtures and using original sockets there is no physical problem installing T12 lamps as that is what they were originally designed for.

 

[hillbilly1]

Actually T5 lamps are based on a European metric standard and are not the same lengths as domestic florescent tubes.

I noticed that, but didn't give it much thought as why, so that is the reason then?

 

[Electric-Light]

I noticed that, but didn't give it much thought as why, so that is the reason then?

So they'll fit in 60cm x 120cm grid system. The 119.8cm T8/T12 can't be made to fit within 120cm fixture.

 

[broadgage]

It's amazing they didn't make them idiot proof, with a different tomb stone.

Here in the UK, T8 andT 12 lamps are intended to be interchangeable in many applications.

T12 lamps came, first and T8s were intended to be a slightly lower energy replacement in existing fittings.

5 foot T12S were 65* watt, and the T8 version is 58 watts.
4 foot T12s were 40 watt, and the T8 replacement is 36 watts.

Copper iron ballasts with a starter switch will work both T12 and T8 lamps.
Starterless copper iron ballasts wont reliably start most T8 lamps, they are for T12 only.

Electronic ballasts intended for T8s will work T12s just fine.

Some new fittings are designed to reject the older style T12 lamps in the interests of saving energy. T12s are nearly obsolete in the UK.

*The very first 5 foot lamps in the UK were 80 watts. Modern 58 watt T8 lamps should not be used on 80 watt ballasts, but are fine on 65 watt ballasts, this being the intended use.

Slightly O/T but I have used modern T8 58 watt lamps on old 80 watt ballasts in a walk in freezer. Overunning the lamps thus reduced the life but gave a much improved light output at very low temperatures. On the correct ballasts the lamps took ages to strike and then gave a poor light.

 

[Electric-Light]

In Europe land, F40T12s run on choke ballast which is just one in-line coil and a glow starter.

This setup would work on 277v service, but 120v doesn't provide enough OCV to sustain reliable arc, so we use step-up transformer and rapid start.

A US spec F40T12 electronic ballast should be able to start TL'D 36W, but starting voltage is substantially higher, so they won't start on rapid start magnetic.

Your TL'D is designed for 430mA choke ballast running off of 230v supply. It's a Krypton buffered type.

Our F32T8 is 265mA argon fill and runs at a higher voltage.