Best way to protect from lightning strikes?

[Yooshaw]

My setup: AX6000 with latest Merlin, with 2 switches downstream to various locations around my 2 story house (basement and main level). All major electronics (including modem, router, switches, etc) are on surge suppressors or battery back-up.

Last evening during a thunderstorm in Colorado, we were startled by an extremely loud bang and flash of light. Sounded like it happened a block or two away behind us. No power interruption at all. Shortly after, we noticed the wifi was down. Went to investigate, and the AX-6000 only had a faint power light on. The wan, lan, wifi lights were off. Modem was on and fine. Odd I thought, I'll just unplug and reboot. No change. Tried a hard reset, no change. One of my switches had no power lights or activity (it's dead), while the other was still working.

After dusting off my AX-88U I had on the shelf, I got everything working again (minus the dead switch, but the 8 ports on the AX88U made up for it). Also discovered that one of my devices (NVIDIA Shield Pro) lost it's LAN port.

I've deduced that the nearby lightning strike induced voltage in my lan runs throughout the hosue, and is probably what caused the damage.

What can be done to prevent this kind of damage in the future?

 

[Tech9]

You can't prevent it. Usually around 100-300 million volts charge finds its way. I had dead equipment twice through all the groundings and surge protectors done by the book. The voltage is so high it goes through meters wide air gaps and nothing guarantees survival of whatever is in the way. Home insurance including lightning damages may eventually offset some damage costs.

 

[Analog-1]

Yep what Tech9 said.

 

[degrub]

My setup: AX6000 with latest Merlin, with 2 switches downstream to various locations around my 2 story house (basement and main level). All major electronics (including modem, router, switches, etc) are on surge suppressors or battery back-up.

Last evening during a thunderstorm in Colorado, we were startled by an extremely loud bang and flash of light. Sounded like it happened a block or two away behind us. No power interruption at all. Shortly after, we noticed the wifi was down. Went to investigate, and the AX-6000 only had a faint power light on. The wan, lan, wifi lights were off. Modem was on and fine. Odd I thought, I'll just unplug and reboot. No change. Tried a hard reset, no change. One of my switches had no power lights or activity (it's dead), while the other was still working.

After dusting off my AX-88U I had on the shelf, I got everything working again (minus the dead switch, but the 8 ports on the AX88U made up for it). Also discovered that one of my devices (NVIDIA Shield Pro) lost it's LAN port.

I've deduced that the nearby lightning strike induced voltage in my lan runs throughout the hosue, and is probably what caused the damage.

What can be done to prevent this kind of damage in the future?

Incorrectly earthed or a broken shield on cabling could do what you describe but usually only for outdoor cabling. More likely, since your damage was limited to only parts of the house cabling , is elevated earth potential from the bolt dissipating through the earth. Your building electrical distribution box (breaker box) is tied to a grounding (earthing) rod that would experience the elevated potential. It is possible that earthing point is not in good contact with the soil or has low moisture in the soil around it. There are ways to test the resistance to earth, but some folks just use three rods connected together to improve the earthing resistance. There can be enough voltage ( >25 - 50 v usually) on the Neutral side to break down the zener diodes used to prevent reverse current flow into the electrical device such as a router, switch, computer, etc. Most lightning is in the 30-70 negative KV range with extremely high current. Anything providing resistance to the current flow will either spark or melt/vaporize. You can put a whole house lighting arrestor/diverter at the breaker box to reduce the amount of energy that gets onto your internal wiring. You should seriously consider replacing all of the surge arrestors in the house as the MOVs used to provide the protection get chewed up with each incident. A competent local electronics repair shop should be able to do it. Otherwise, replace the units. They should be replaced every 5-7 years anyway. i live in a high lighting frequency part of the US and have experienced 3 very close strikes (within 100 ft) over a few decades.

BTW, if you experienced the strike as a flash-bang with no gap between the two, it was likely a very close strike to earth, maybe not down the block. Are you within the front range or out on the prairie ?