On Tue, 25 Sep 2018 13:32:13 -0700 (PDT), whit3rd
wrote:

On Tuesday, September 25, 2018 at 12:41:01 PM UTC-7, Ned Simmons wrote:
On Tue, 25 Sep 2018 12:08:10 -0700 (PDT), whit3rd
wrote:

On Tuesday, September 25, 2018 at 5:54:11 AM UTC-7, Ned Simmons wrote:
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd
wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons wrote:

...you can't just connect parallel strings of LED's

Yet, it's done all the time.

Or you could avoid the work-arounds and potential pitfalls: pitch the
ballasts, and purchase lamps with built-in LED drivers that operate on
line voltage.

What kind of 'built-in LED drivers' are you thinking of? Gizmos that
switch OPEN when the current goes too high?
No.

Or, complete current-regulated
DC power supplies?
Yes. I haven't pulled one apart, but I'm pretty confident that the
replacement tubes I purchased have constant current switching power
supplies.

Something as reliable as a magnetic ballast is not
going to look like a silicon IC, and take AC line input, and spikes, gracefully.

I've been designing, building, and installing automation and machine
tools in industrial settings for 35 years. For most of that time the
bulk of the low power loads in control systems have been powered by
switchers with universal inputs; typically 100-265VAC. I've seen very
few failures, so it's possible to build such supplies that survive in
nasty electrical environments. Another example is electronic
fluorescent ballasts, which are only slightly less reliable than
magnetic ballasts.

The quality of the supplies in LED fluorescent replacements
undoubtedly varies and is a legitimate question, but my experience so
far has been more than satisfactory.

--
Ned Simmons