On 12/6/2010 2:09 PM, Mike Marlow wrote:
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

Trying, usually, to answer questions for myself before and after I
post, I ran across the following tidbit. It isn't that helpful
though. BTW, I have no reason to believe THD is accumulated if
fixtures are wired in a series, but I would certainly be interested
in knowing if anything of that nature is true.


THD stands for Total Harmonic Distortion. The distortion is feedback
caused by deviation from the sinusoidal waveform. The industry
standard is less than 20%. If the THD is very high (around 150%), an
electrical fire can occur. Magnetic ballast run 90%-120% THD.

The information above was copied from :
http://www.ace-ballast.com/articles/...last_Questions

Bill

Interesting stuff Bill. Though - I doubt I'll worry much about THD on the
next flourescent light I purchase.

You'll probably save $14 too! I'm considering purchasing about 15--and
I want 'em quiet! : )

When I built my last computer, I used a fanless graphics card and tossed
in an extra $100 for a quiet (decent quality) power supply. No hard
drives either--SSD. Maybe having quiet is a lot like having a sharp
Brad point drill... : )

Bill