A Sad Story


Senior Member
I always thought I was pretty well protected from lightning and surges. I have surge protecters on everything. I even have Brick Wall series mode surge protectors ahead of the UPS's on my PCs for double protection. Unfortunately that wasn't enough for the storm that roared though here the other night.

We had several close lightning strikes (one of them set a nearby house on fire) and a lot of power flickering but I thought I was OK because of all the protective equipment. After it was all over I took an inventory and found I had lost an RS-485 hub, the serial ports on 2 PCs, and the serial interfaces on my phone system and my Stargate. This surprised me because none of my serial cabling connects to "unprotected" equipment and I had never had failures like this before.

I don't know if the issue relates to each end of the serial cable connecting to equipment with slightly different ground points or different AC legs or what but I need to figure it out before the next storm does some serious damage.

Anybody using surge protection on their in-house serial lines and if so, what do you use? Do I need to switch to opto-isolated serial cards in my PC (at $200 a pop), or put surge protection at each end of each serial cable? Any input would be appreciated.
I have heard that serial surge protectors may help, but as always with lightning, nothing is guaranteed. I used to use them on serial terminal lines I ran for a business, Radio Shack used to sell them and those weren't that expensive. I don't use any at home, but I don't have any long serial lines.

I have heard that you can make your own surge protectors with a simple MOV between each lead you want to protect and the ground lead. How well this compares to commercial protectors, I don't know.

I have also heard that long cables lying on the ground (TV, phone, serial) can pick up enough stray voltage to damage equipment just from the ground field.

If anybody has facts or stories to back up what I heard or to contradict it, please post. I live in central Florida, lightning capital of the US, so I should be following "best practices", but I probably am not.
I had 2 lightning strike failures on a pan & tilt device on a bridge over my stream. The first time, it fried my PC's serial ports. The 2nd time, it fried the servo card in the P&T. Before I installed another panner, I checked the AC and discovered the ground was open.
These same storms killed some of my equipment as well, these thunderstorms were pretty nasty, and looks like it might continue for a few more days :huh:
Man, I do feel for you! Sorry that happened.

Last summer late in an evening I was at my computer (in my den) when a lightning strike happened right outside the den window! I just saw a big flash of light, the (CRT) monitor went off and on (like it was going through a degause) and get this, my industry grade Caddx Security system (NX8E) disarmed itself!

I also felt the hair on my arms raise. It was really weird. I also had to check the old shorts for, well... :huh:

When I checked for damage (shorts were fine BTW), the Caddx NX8E security card had a non-working serial port and could no longer communicate with the Homeseer PC. (Everything else worked, just that one feature was no longer functional).

I since then grounded the Caddx system to earth and have my equipment in my wiring closet (Caddx, Ocelot, SECU16I, RLY-8, Elk 12V Supply, Elk Amp, etc...) on its own small UPS. But, I'm not sure that would have saved my serial line as stated above. What was strange is that nothing else even glitched (Ocelot serial line, NetCaller ID serial line, MR26A serial line).
Yep, we also had some nearby hits.. So far all has survived (knocking on wood), but the storms still continue as we speak.
I've had serial port damage as well.

In some devices, it was just the level converter (like a MAX232 chip) that was damaged. It was easy to swap chips and be up and running again. I've never lost a port in the computer, just between other devices. But in one string of two devices and the computer, it was the first device and the MAX232 in the second that blew. I assume the dead MAX232 helped protect the computer.
You know, I've had a lot of people swear by thouse whole house surge protectors. I've been thinking about installing one in my house. Does anyone have any experience with them? If you have, did you install the residential or commercial grade ones?


I install a Cutler Hammer CHSP 3-way about two years ago and have not had any more unusual failures .... is it working or just luck????... how would you know??
Unfortunately, the only way you know with lightning or power surges are when they DON'T work. But then you wonder "would product X have saved me? maybe I should have bought product Y."
IMHO, lighting is weird and unpredicable. Quite often, it does its damage not by coming in through the powerlines, but a nearby strike can induce enough of a spike by "coupling" for lack of a better word, that will take out various components, but leave others alone.

I've have the tops of transistors blown off in a TV, but the VCR (pre DVD days), was untouched and worked fine. The TV cable went to the VCR then to the TV, and both plugged into the same electical outlet. Go figure.

Martin, the whole house surge suppressor would be a great idea, and would protect a lot of items from the surges and spikes that come in over the powerlines.

But, I'm not sure if anything could really protect from Lighting, since it doesn't have to make direct contact with any of the wiring to do its damage.
I installed a Panamax Whole House Surge Suppressor. I don't know if it has helped or not, but so far no failures... I figured it can't hurt.

I also have everything electrical protected with local strips. I talked to my phone company and they said my phone line has a protector on it at the demarc, but that I can't install another one inside due to my DSL line.
Thanks for all the feedback. I don't use ordinary local surge strips because I can't always tell if the MOV is still at 100% or if it is compromised from previous surges. For local protection I use these Brick Wall series mode protectors.

I think one weak point may have been a remote RS485 hub that I powered with an ELK 12VDC alarm type power supply (so it would work during a power failure). I figured the power supply would protect the hub from surges but I guess I better get a protector on it and continue looking for other unprotectd devices.

I have held off on a whole-house protector because I was not sure what it would do to my X-10 signals. I have a Square-D breaker panel so maybe I will try the surge protecter they make that snaps into a breaker slot.
I'm very late to this thread, but I'll give it a go anyway.

I've had a surge burn out the com ports on the computers hooked to my OmniPro twice now. I've got a whole house surge protector, along with cable and phone protection, as well as a UPS for the computers, so I'm assuming it got in through the long runs on the alarm system. I ended up putting APC RS232 surge protectors on all the serial lines between the alarm system and the computers, and I haven't had any trouble since.