re:Instant Start

> From: Erik Olson <eriko at wrq_com>
> > From: "shaji (s.) bhaskar" <bhaskar at nortel_ca>
> >
> > To set the context - both bulbs *and* ballasts are classified as
> > either instant-start or rapid-start. Most combinations of ballasts
> > and bulbs will work:
> >
> >                          Instant-start bulb    Rapid-start bulb
> >                        -----------------------------------------
> > Instant-start ballast  |        OK            |      OK        |
> >                        -----------------------------------------
> > Rapid-start ballast    |     WON'T WORK       |      OK        |
> >                        -----------------------------------------
> >
> > Rapid-start bulbs have two pins at each end, while instant-start bulbs
> > have only one pin at each end.  What Erik is using is apparently an
> > instant-start ballast with rapid-start bulbs.
> Are you sure 'bout that?  I wonder if the two pins in the T-8 48" bulbs
> are there just because a 1-pin 48" mounting doesn't really exist.  (Note
> this is pure speculation; I have no facts to back this up, at least until
> I go talk to my local lighting people).  Are folks using rapid-start
> ballasts with T-8's?

I'm positive that instant-start (I-S) ballasts can start rapid-start
(R-S) bulbs.  I am also positive that T-8 R-S bulbs and ballasts
exist.  As to whether your particular bulb is I-S, I can't really
say. It is possible that you have an I-S bulb with two pins just so
that retrofits of existing fixtures are easy (retrofits are a big
market segment for commercial lighting).  My best guess is still that
your bulbs are R-S.

Here is a related quote from http://www.facilitiesnet.com/NS/NS3ball.html
by Steven Mesh (a man with impeccable credentials, he's apparently an
academic :-)) on the differences between R-S and I-S.  BTW,
http://www.facilitiesnet.com is a good site for lighting info - just
use the search engine. 

*********** Begin Quote **************

Rapid-start fluorescent lamps contain electrodes (filaments) at either
end of the lamp. They can be identified by bi-pin bases. These
electrodes are preheated for at least one-half second. Once the
electrodes are brought to the appropriate temperature, the arc is
struck and the lamp produces light. Instant-start lamps have
single-pin bases, so there is no opportunity for preheating the
electrodes. Instead, the ballast applies roughly three times more
voltage to the lamp than a rapid-start system.

This jolt of electricity can be detrimental to the life of the lamp's
components, especially the electrodes. Therefore, instant-start lamps
typically have a rated life of 15,000 hours versus 20,000 hours for
rapid-start. These figures are based on three hours of operation per
start. In the past, many lighting systems were designed on the basis
of 12 or more hours of operation per start. At that rate, both lamp
types approach the same life -- 29,000 hours.

Incidentally, rapid-start lamps can be operated by instant-start
ballasts. In this case, the life of the rapid-start lamp is derated to
15,000 hours at three hours per start. Instant-start lamps cannot be
powered by rapid-start ballasts since there is only one pin at each
end of the lamp. (Preheating of the electrode requires a complete loop
of electricity, hence the filament and bi-pin base.)

Typically, rapid-start lamps maintain the electrode heat during normal
operation. This consumes an additional three watts of power not
converted into light.  Instant-start lamps do not require electrode
heating. Therefore, an instant-start lamp and ballast combination can
slightly reduce energy use. This is a similar technique to using a
hybrid (heater cutout) ballast.

Depending on the operation of a particular facility, it may be
possible to save money by using instant-start technology. On the other
hand, many states now require owners to equip their facilities with
motion detectors, infrared sensors, local wall box switches and even
photocells for daylight sensing. In these cases, the energy and cost
savings may be diminished because the reduction in lamp life will
increase costs for relamping and labor.

********** End quote *************