"Smarty" wrote in message
...
Just for the record, I have to report that fluorescent fixtures do not
***ALWAYS*** perform the same as incandescents even if they are wired the
same:

I purchased 24 fluorescent strip lights from Home Depot, each containing
an electronic ballast and sockets for 2 fluorescent T-8/T-12 style 32 watt
bulbs. These fixtures use the newest electronic ballasts, are extremely
efficient, make no hum or other noises like magnetic ballasts, and were on
sale for $6.99 per fixture.

When they were all installed as three sets of 8 fixtures, each set on its'
own circuit/switch, I found that an extremely high rate of failures
occurred, arising from what I subsequently learned is called "ballast
fratricide", a process wherein the switching transients from the ballasts
all being simultaneously switched results in spikes which the ballasts are
unable to dissipate without damage.

It turns out that strip lights especially are not filtered adequately,
neither in terms of the emitted spikes which damage other nearby/connected
loads, nor in terms of rejecting fast transient spikes which arise
elsewhere and need to be dissipated.

I spent some time with an oscilloscope and a lot of measurements before
being able to find where the problems were, and have subsequently learned
that others have reported the same type of problem with the newest
electronic ballasts in some commercial installations.

If one takes an in-depth look at the schematic and waveforms produced by
the electronic ballast during the start-up cycle, and also looks at the
chipset spec sheets from the ballast ICs involved, it becomes apparent
that huge switching transients are typical, and that external filtering is
up to the fixture designer who incorporates these ICs into their ballast.

The bottom line is that some fluorescent fixtures cannot be simply wired
as if they are incandescents, since they will destroy their neighbors and
themselves, in my case over only a few days of normal use.

My solution was ultimately to replace all 24 ballasts with another, better
filtered design which, unlike the Home Deport brand, have a lot of spike
filtering as well as a 5 year warranty.

Here is another example of this type of problem:

http://lighting.copperwire.org/7.2.php

Smarty

@ 6.99 per light, you got *exactly* what you paid for.