Bill writes:
On 12/6/2010 11:01 AM, Bill wrote:
On 12/6/2010 10:50 AM, Bill wrote:
Someone suggested (I could not locate the post) that if I wanted quiet
fluorescent lights, then I should look for those with an "A" rating.

Putting that detail aside temporarily. What would be the practical
differences between a "standard electronic ballast with 20% THD"
and an "instant on electronic ballast with 10% THD"?

Bill

Continuing to research my question, evidently low THD is better for
the components in the lighting system (capacitors, etc) and may provide
lower cost in the form of the longer life for the system.


Pitiful question: If 8 fluorescent fixtures are wired in a series, and
the ballast in one of them fails, do all of the lights go out? Assume a
"modern" fixture.

Why would you ever wire them in series? Each ballast needs to be
connected to the next in parallel when they're on the same circuit.

Some two-lamp ballasts (usually older magnetic) will wire the lamps
in series, and losing a single lamp (bulb) may cause the other bulb
to not light. This is generally not a problem with electronic ballasts.


If the answer to the question above is yes, this suggests "Lew's wiring
design" should be wired (using 12-3 THHN) with 2 parallel (pairs of)

There is no such thing a "12-3 THHN".

The ballast in each fixture must be wired in parallel with respect
to all other ballasts on the same circuit the same way one wires multiple
incandescent fixtures on the same circuit.

----black------------+----------------+----------------+
| | |
ballast1 ballast2 ballast3
| | |
----white------------+----------------+----------------+

scott