On Thursday, December 3, 2015 at 7:47:53 PM UTC-5, wrote:
On Thu, 03 Dec 2015 14:08:34 -0700, Don Y
wrote:

No, that's the lazy approach. That's the way auto mechanics start swapping
things (charging you for each "new replacement" -- even if it didn't FIX
the problem) out until they stumble on the "solution".

Since you are not paying for things you try that is not really a good
analogy but without the right test equipment, eliminating things in
the path is probably the only real way to go.


I always start on the path of trying to fully diagnose the problem
instead of swapping parts. But anyone who has worked on cars has sure
had many times where they wished they had the dealers stock of parts
to try swapping something that is easily swappable to see if it fixes it.


If I was really willing to "diagnose" this I would get a device type
GFCI, Disable the trip mechanism and look at the output of the
differential amplifier with a scope as I plugged in the lights, cords
etc looking for the one that is the offender. You could calibrate your
result using a pot and introducing a known fault value.
My bet is you will see this thing cruising in the 3-4 ma range so any
little glitch pushes it over.

Agree, that's the problem and why you're left with swapping. To conduct
the required tests is going to require some advanced gear that homeowner's
typically don't have. Even if I had it or had access to it, I wouldn't
waste my time trying to figure it out.