On Monday, May 17, 2021 at 5:31:41 PM UTC-4, wrote:
On Mon, 17 May 2021 12:29:59 -0700 (PDT), "
wrote:

On Monday, May 17, 2021 at 1:34:55 PM UTC-4, wrote:
On Mon, 17 May 2021 10:10:08 -0700 (PDT), "
wrote:

On Monday, May 17, 2021 at 12:10:47 PM UTC-4, wrote:

My spa controller is 4xxx CMOS but my pool controller is all relays
and switches with a cam timer on a 24 hour gear motor shaft.
Power surges will not hurt that although the 4xxx CMOS has lived
through 35 years of lightning strikes and power hits.

I may have posted this before, but this is a really good product and worth every cent.

https://www.amazon.com/Delta-LA302-R-120-240V-Lightning-Arrestor/dp/B006H3U4HS/ref=asc_df_B006H3U4HS/?tag=hyprod-20&linkCode=df0&hvadid=309804813335&hvpos=&hvnetw= g&hvrand=12948758990071981512&hvpone=&hvptwo=&hvqm t=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9010378&hv targid=pla-568919638940&psc=1

I have three on my house... one in one of the two, 200amp breaker boxes, one on the
well pump pressure switch, and one in the breaker box for my shop. I've never lost
anything to surges, at least that I know of. They do make several different products for
different applications.
I have several of those MOV protectors in the system along with some
point of use protectors.
It is important that you have all wires coming into your house
protected (cable, phone and power). All should be tied to the same
common grounding electrode system with the shortest wire possible.
You also need to be sure your grounding electrode system is good. A
ground rod or two isn't going to cut it.
I have a number of electrodes but the pool and concrete deck is
probably the best one. Everything is bonded.

Yep, it's not the potential (voltage) that kills things, it's the difference in potential. Years ago I went to
the fire lookout tower on top of Mt. Hough, Plumas County, California. The amount of grounding
was unbelievable. The four corners of the building had heavy ground wires that ran out across
the mountain top and had rods driven down through the solid rock. The idea is to keep everything at the
same difference in potential. The whole top of the mountain rose, then drained off. If the circuit runs off 5 volts,
but a strike causes the 5 volt buss to rise to 1005 volts while the ground buss rises to 1000 volts, then the
chips and circuits still see just a 5 volt difference. Nothing pops, everything is bonded together.
They said it gets struck several times a year, and they rarely lose anything. Probably gets
exciting for the lookout person, though.
That is pretty much how they did all of those radio towers along I-75.
There was a ground ring around the whole complex with 40' rods. the
concrete was all bonded as a Ufer and they ran 2ga bare radials out to
the ring.

Those had another purpose. They formed a ground plane for the antenna to work against. It's common
for any commercial antenna tower to have radials extending out from the base. Think about those CB
antennas from the 70's. One radiator going up vertically, with four sticking out horizontally
at 90 degree angles. Those formed the ground plane, and allowed the vertical radiator to perform as
it should. The towers also benefit from the same technology. "Ground" (dirt) isn't always conductive enough.


The toll complex at MM99 was done almost the same except the poured
concrete duct banks going out to the booths was also part of the
ground electrode system along with the building footers. The duct
banks were 6 feet down to the top of the concrete. It the wet season
they will be underwater.
I have taken at least 2 direct hits to the lightning rod on top of my
weather station. The first time it took out a serial port. The second
time, after I added more mitigation, all I had to do was reboot the
PC. On that second hit, I was in the driveway. It was exciting.

I had a lightning bolt hit a pine tree about 30' away some years ago as I was getting out of my car.
I had just opened the door, and hadn't put my feet on the ground yet. Good thing.
I closed the door and sat there for a few minutes to get my **** together. Then I bolted to the front
door of my friend's house. They were happy to see me alive. It took us all a couple of strong drinks to
calm down.

We used RS422 in our systems to mitigate the effect. RS232 is refenced to ground, 422 isn't (balanced pair).
If you shielded the 422 and grounded things properly, you had better luck surviving. If it was a real concern,
you used fiber to run the serial ports out to the operator positions. Problem solved.