Why whole house surge protectors are not enough

I should have added, that I had a whole house surge suppressor in place on the outside panel also.

I’d like to second your callout regarding surge suppression and LAN protection from your blog. A few months ago we had lightning hit a tree that was just 15 feet from our electrical entrance with is underground.

@upshift Sorry to hear that but really interesting.

I want to warn you not to use grounding Ethernet arrestors inside your home. Use those, if any, outside or as close to that edge. Inside stick to isolators. The most recent thinking I’ve seen is that grounding Ethernet cables during a surge just allows a high current surge to form through MORE devices when otherwise you wouldn’t have one. Better to isolate the gear and let lightning find a path through a single device and it’s power cable than to form a long circuit and let it take out even more devices downstream. So far during the worst of the lightning I’ve only lost a cable modem, which wasn’t mine anyway. 😁

Alternatively, use fiber converters to air-gap your gear.

After installing my whole-house suppressor lightning took out a laptop. It was the only PC in my home that was plugged in but NOT on a surge strip.

The same way audiophiles are kind of ridiculous with having too much gear to play music, we also have a lot more Ethernet devices hooked up than the average person, though hard core gamers are close.  For many Americans who have Internet access Wifi is the only connection they use and lightning is not the same problem than for someone like me who has a dozen items hooked up via copper networking cables.

@erik_squires  Thanks for the update, I didn't realize that.  I am using a grounding type arrestor, I'll check out the isolators.  I am using optical between my router and my audio equipment, mainly to replace a 50' run of ethernet cable.  Have a plan in place to do the same throughout the house.  Would be nice to see optical connections supported on more equipment like modems and routers but realize that it may be a limited market.

I am using optical between my router and my audio equipment, mainly to replace a 50' run of ethernet cable

A solid idea in terms of minimizing surge risk at least.  The longer the Ethernet cable, the more the antenna effect it can have.

I want to point out that lightning entering the Ethernet system without actually coming through the cable provider’s wiring is an edge case, but exactly the sort of problem I’m worried about.

That is, my guess is that 90% of home network surges happen from the copper that goes from outside to inside of the home, and the remaining are from induced (EM pulse) currents from INSIDE the home Ethernet wiring.

The longer a run of Ethernet the better it may pick up a lightning surge. From what I’ve read this danger starts around 30’ long runs.

Once the wiring is involved the next question is how will it find a path to ground? That path is often through a power supply somewhere. Once that gap is broken through everything in the way will fry as the surge arcs over. In these cases shorting (MOV) based surge protectors become co-conspirators by offering a low-volrage gap to ground.

Network isolators work by increasing the necessary arc-over voltage by 4kV at a time. This forces the surge current to look for a path with less resistance to ground which hopefully involves fewer devices.

And this is the thinking I've read lately.  You may not stop the surge current, but you can reduce the total number of connected devices involved.  If you fry a cheap switch instead of your switch, TV, streamer, PC, etc. it's a good thing.