Mixing ballasts and tubes

[oil pan 4]

Do at your own risk.
Lethal voltage and current present in on energized systems.
But it seems to work. It all started where I work, had some T5 high output lights with burned out ballasts.
But our supply department was out of T5 ballasts and hadn't ordered more but they had standard 34w T8 ballasts (non rapid start) and my boss who had been an electrician for a long time told me to put T8 ballasts in them and rewirw th like a T8 so I did.
This started 2 or 3 years ago.
The 34w T8 ballasts powered T5 lamps are still working just fine to this day. So I know they work and work for a long time.
They are just not as bright, which is to be expected.
So ballasts are expensive, I'm cheap, plus I consider reduce, reuse and recycling hobbies.
I figure that even if the T8 ballast powered T5 lamps aren't as efficient as T5 ballast powered T5 tubes it will take a long time for an occasional use light to use up the $30 to $40 difference in KWHs.

So I have 2 types of ballast left over from my t8 LED upgrade.
I have some old looking and heavy T12 rapid start ballasts for 4 foot 40w tubes, this tube ballast combo sucked the tubes wouldn't even come on at or below freezing.
These may just be junk.
But it would be nice to have some free 40w rapid start ballasts for my dead T5 fixtures.
The other standard T8 ballasts are non rapid starting but will work fine for lights that are kept inside.

I found that pin to pin on the rapid start T8 tubes is about 2 ohms, my German made T5 pin to pin are 1.1 ohm, the cheap Chinese GE T5 tubes are 1.6 ohms pin to pin.
So the GE tubes are going on the T12 rapid start ballasts, so the end filament doesn't get burned up as fast.

Note: all T5, T8 and T12 light fixtures are 4 foot and all ballasts used are listed for use on 4 foot tubes.