We had a lightning strike nearby yesterday that looks to have come inside
our facility via a feeder circuit that goes outdoors underground to our
facility's gate.
Perhaps there was a "move" of the earth-level relative to the neutral
line.
I have no idea how neutral-line to earth potential is handled in us, but
here in austria we use a so called "nullung".
That means that the earth-ground potential line of the building (which
includes also the lightning conductor) is connected to the neutral power
line where it enters the building, keeping this potential-difference low.
Theres also a potential between earth ground and the neutral-phase of the
online-ups.
The ethernet-cables; utp or stp?
pannels correctly earthed?
Perhaps a electrician should check the earthing.
Also all copper lines that enter the building should be protected by
lightning protectors.
Kind regards,
Ingo Flaschberger
