I manage IT for several clients in Central Florida, where we have quite a lot of lightning (the most in the U.S.). I have one client that has trouble keeping electronic devices alive. We have replaced several network devices. I suspect there is a problem with the grounding or surge/lightning protection. I am not worried solely about that electrical system. The ethernet network seems to be a problem as we keep losing individual ethernet ports on devices. Some of the devices keep working, but individual ports are dead and we just move connections to previously unused ports. But it is not clear to me if the hardware is dodgy or the facility is more vulnerable than others.

I have previously asked this on networkengineering.stackexchange.com and the only advice I got was to hire an electrician. I can do that, but I am not sure I can trust someone to not just sell me a lot of remediation services that do not improve anything.

Is there a device I can buy or a process I can follow that can show me what, if any, wiring is bad? I have a simple wall plug AC outlet ground tester widget that I plug into outlets that tells me if the something is obviously bad, but that doesn't help me with surges or ethernet.

If I do hire an electrician, I would like some way to verify this personally without relying on someone else.

  • \$\begingroup\$ Does keeping stuff alive mean that certain devices fail and have to be repaired or replaced? Does losing ethernet ports mean a temporary thing that is fixed by a reboot or, do you have to mend/replace? Ask your client what specific surge protection devices they have fitted and where they are fitted. \$\endgroup\$
    – Andy aka
    Commented Sep 14, 2020 at 16:42
  • \$\begingroup\$ @Andyaka Thank you for asking. I have edited the question to add more details. We have had individual switches and firewalls fail. In some cases, the switch or firewall just has a port that is permanently dead. Reboots do not fix the problem. I have asked the client and he thinks he has surge protection. But I do not know how to verify that. \$\endgroup\$ Commented Sep 14, 2020 at 16:51
  • \$\begingroup\$ Well, I'm designing something right now and I've been waiting for my client to tell me what SPD they have upstream for about a month. Can't really move on the design until I find out. Sometimes you just can't get answers and sometimes folk don't appear to know that answers are important so you can design things properly without comeback if things fail. \$\endgroup\$
    – Andy aka
    Commented Sep 14, 2020 at 16:56
  • \$\begingroup\$ Surge protection is usually pretty apparent. It's a device that the equipment plugs into and it has a connection to ground. They might have a service entrance protector located near the power panel, but that will not protect the ethernet depending on how long the wire runs are. Panamax makes some ethernet protection modules: panamax.com/product/module-cat5-ethernet-MOD-CAT5 \$\endgroup\$
    – Aaron
    Commented Sep 14, 2020 at 17:46
  • \$\begingroup\$ "I would like some way to verify this personally without relying on someone else." - a good electrician should be able to draw you a diagram (bubble of protection) on how protection needs to be added, and how it works to protect your equipment. \$\endgroup\$
    – Aaron
    Commented Sep 14, 2020 at 17:49

3 Answers 3


Lightning protection is difficult to check, because many of the devices are rated for single surge protection. Testing them would be like testing a match - yes, it worked... once.

Most important is proper design, from bottom to top.

  • Provide a large, low resistance ground. If the soil is dry, add copper sulfate and water regularly.
  • Use low-impedance, heavy gauge ground wires, keeping it as straight and short as feasible.
  • Bond all nearby conductors, such as rain gutters and drain pipes.
  • Use a lightning arrester on each wire that enters the building, and ground the arresters correctly.
  • Avoid cable or wire runs parallel to outside conductors, such as the ground wire or rain gutters, to minimize inductive pickup.

And the list goes on and on.

If Ethernet is a particular issue, use a surge protector on each port, again, keeping the run to ground short and with few turns.

Finally, lightning releases immense energy in a short period; on the order of gigajoules in milliseconds. Given a direct hit, expect some devices to fry.


Well, there are special measurement devices... I just did a quick search for something available in the US


With such a device, a trained electrician can test a local installation to provide values which are covered by the standards, rules and regulations.

appart from that you may want to look into lighting protection, here I can name you a company I know and which I use in my house


What you want to have is a cascade of Type 1,2 & 3 Surge protectors for the Power supply (with Type 3 is in your UPV, or in multi sockets).

also you can do more for IT Equipment


like connect screens of the Ethernet cables with ground more often, so you get a mesh with low imperdance.


Especially make sure the customer connects all (!ALL!) earthing points e.g. of switches with GND using SHORT single core wires of appropriate diameter to the ground rail (good cabinets have more than one).

No need to mention: measurements and installation should be carried out by trained and certified persons!


Central Florida has a vast variation of soil types. Brother of mine explained that part of Florida was BEACH_FRONTAGE just 20,000 years ago.

  • dry sand

  • muck

  • some clays, if I remember rightly

Any lightning protection needs to accommodate the soil type under the at_risk buildings.


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