In article , walter wrote:

I am switching from T12 shop lights to T8 shoplights. Still have several T12
fixtures. I bought a lot of T8 bulbs but I am out of T12 bulbs.

Can I use T8 bulbs in fixtures that previously used T12 bulbs? Of course, T8
bulbs are 32 watt and T12 are 40W. Will the T8 bulbs kill the ballasts in
my remaining T12 fixtures? Will the old T12 ballasts kill my new T8 bulbs?

I have seen 2 T8 bulbs in a fixture that apparently has a T12 ballast.
The bulbs have trucked on over a year already.

However, there are predictable effects from the abuse case of running
32W T8 bulbs from a 40W-per-bulb T12 ballast:

* Bulbs may have trouble starting, sometimes intermittent. (T8 bulbs
have a higher requirement of ballast output voltage than true 40 watt
T12 bulbs have.)

* 32W T8 bulbs powered by a 40W/bulb T12 ballast can easily be
overpowered if they start. That is likely to shorten the life of the
bulbs, fair chance disproportionately.

* A 32W T8 bulb being powered by a 40W/bulb ballast can have its running
being less stable - as in increased vulnerability to flickering effects
and increased effects of cold temperatures on stability and ability to
start.

There is another matter: Using a bulb of type other than the one or
ones on any combination of the ballast label (or nameplate), fixture
label, fixture documentation or fixture packaging - is abuse of electrical
equipment. Fire insurance companies could give huge major trouble if a
fire starts in electrical equipment that is being abused. You could need
a good lawyer and good expert witnesses to have only fair-good chance of
prevailing if the fire was caused solely by factors other than abuse of
electrical equipment.
--
- Don Klipstein )