Thierry wrote:
"I am interested in your experience."

My electric utility company`s service standards book says:

"National Electrical Code (N.E.C.) requires grounding to a "metallic
underground water piping system" if available. Acceptable alternatives
include a driven ground rod which is preferred by your company
regardless of the type of grounding used. N.E.C. requires that the
"interior metallic cold water piping system" be bonded to it."

My home installation has metallic water piping inside and outside the
house. A heavy cable connects cold water pipimg to the electrical
service entrance and to an external ground rod.

Telephone and TV cables are bonded to the electrical service ground.
This is done to lessen the possibility of a potential difference between
the various services.

Nevertheless, I had a combination clock radio telephone which was burnt
by a lightning strike. Enough potential difference was generated
between the phone wiring and powerline wiring inside the house to fry
the clock radio telephone which was at the opposite end of the house
from the service entrance where services share a common ground point. It
is a wood frame house.

There was no protection at the clock radio telephone. Had low-pass
filters with voltage-limiting on electrical and telephone outlets been
installed and had they shared a common ground connection at the
apparatus, it is likely no damage would have occurred. I`ve used MOV`s
for power line surge protection with success against common-mode and
differential-mode surges. Carbons and gas tubes are suitable for phone
lines.

I worked many years in broadcast stations, medium wave and short wave.
Never saw a dime`s worth of lightning damage in the well protected
stations in which I worked.

I worked more decades with land/mobile and microwave radios and found
ways to protect these too, mostly by using the same techniques already
perfected in broadcasting. No. We did not use 120 radials for our VHF,
UHF, and microwave towers, but we did use a separate ground rod en each
tower leg. This was lightning protection. We also used closed circuit
antennas grounded at the tops of the towers. Coax rejects common-mode
lightning energy. We used zero protection across coax and never had a
burnt transistor receiver front-end.

Best regards, Richard Harrison, KB5WZi