On Tue, 2022-02-22 at 10:31 -0600, Roger Heflin wrote:
> I have a wind meter on my roof hooked to a device that counts it's
> rotations, and that serial port device would randomly stop working
> requiring a reset of the usb-to-serial communication to get it to
> function again (I had a cron job to reload/reset the usb nightly
> because it was happening often enough). I guessed ground loop ran a
> ground wire to house ground and grounded the hw device doing the
> counting years ago, and that solved the issue.

That one may have been static build-up.  Things with wind blowing over
them often have such problems.

Ground loops are where there's a loop formed by several grounds that
connect together.  When you have faults caused by ungrounded things
that go away when you add a ground, that's not a ground loop fault,
that's a lack of grounding problem.

If you find that strapping the cabinets of equipment together helps
reduce faults, it could be the house mains wiring has an earthing fault
(or the wall socket, or power strip, you're using).

You can find with a lot of modern equipment, they don't ground the
internals, and it becomes susceptible to static build up and discharge
faults.  

Mains spikes can cause failure as the modern groundless power supplies
will capacitively couple active and neutral to the common rail of the
power supplies output.  Now, instead of current going to the mains
power earth, it goes through the equipment.  Even without any spikes,
the output floats at a high voltage, and when you connect things
together sparks fly between the two (hence the recommendation to hook
equipment together *before* plugging the mains power in).  That kind of
thing was the cause of death of CD player outputs, home video camera DV
ports, etc.  They didn't like a 400 volt sudden charge through
something that only worked with very low voltages.


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