lightning damage

[collegeboyslive]

arrrrgh another ocelot damaged by lightning !!

i have surge protection on all the ac lines but i think its traveling in though the data lines.

anyone got any ideas on how to protect this?

[Michael McSharry]

Go west young man. You then only need to strap them down to prevent earthquake damage.

[smee]

For things like serial lines (RS232), there are inline surge protectors that you can buy. I have no idea if they are any good or not.

I have had devices die like this due to lightning strikes before. The actual device was fine, but could no longer communicate with the pc.

If I recall correctly (I don't have an Ocelot), the Ocelot uses RS232 to connect to the PC and RS485 to connect between modules. Check and see what kind of interface chips are used to connect to RS232 and RS485. The RS232 connection will probably use a 16-pin chip (which may be labeled something like "MAX232" - one particular device). The RS485 connections may use something like an 8-pin MAX487. There are many different devices - these are just two examples.

If the device seems ok but won't communicate, it may just be that these chips have blown. Many of them have a certain level of protection built in but it may not be enough to handle the potential caused by lightning strikes.

If you can track down the chips and they are socketed, then maybe all you need to do is replace them.

I assume the manufacturer can help you out if this is the case.

[jay]

CBL.
are these lines running outside? I lost a camera and a pan & tilt servo from lightning. Those are not easy to protect. Maybe with the ground shield via a line to a copper rod. Haven't done that.
On the other hand, are you running data between 2 buildings? In that case the power ground (earth) and hence the data ground voltage potential diffs can be enough to cause damage. Here, I used fibre optics for data transfer as it's non-conductive.
One more step I've taken. I have a hi-gain WIFI antenna to which I've added an inline lightning arrestor. Happy to furnish the info on that to anyone.

[Stuart]

Hi,
coming from a Ham radio background, you may want to investigate a ground ring. This acutally is wire under the ground and makes a complete circle around your house. This in addition to grounding rods will only help your chances of not getting hit again. I had a small antenna tower on my roof with the proper wire and grounding rods, and to my amazement I watched as a wooden pole across the street get hit and burned in a strike.
Stuart

[jay]

Burned at the stake?
half smiley, half amazement.

[huggy591]

Over the years with various lightning strikes and wiring schemes in places I've lived, I've been convinced that most electrical devices that aren't hit directly by lightning are fried by electical potential differences in wiring, or the grounding system. With a close hit, the earth actually raises its potential for a few milliseconds and your grounding rods can become the problem since they are tied both to the ground lug and to the neutral side of the wiring! This potential has to dissipate somewhere...

Long runs of wire can act like an antenna and pick up the EMP of a close strike, which can translate into an electrical potential high enough to fry small electronic circuits.

When I was in Maine, I had an old farmhouse with two-wire outlets - without ground lugs - in my main computer room. While I had all local systems grounds tied together, there was no ground run back to a copper pipe or grounding rod. Only the neutral was tied to ground through the electrical box. I never lost a single piece of gear with local strikes that came close to the house, including the one that hit the tree across the street.

I later moved into a newer home which had "proper" grounding, and with close strikes I began to lose modems, TVs, and cable gear even though they were on UPS systems, but they were hooked to the phone line or cable TV system with a long wire... I had a Curtis surge supressor outlet strip that went up in smoke from one close strike, but the items plugged into it didn't get damaged at all!

So the short story is to reduce the electrical potentials being raised by the lightning strike by keeping wiring short, all wiring surge-supressed, and gear on protected circuits.

We just had a close strike - within 1/4 mile - a couple hours ago and nothing here has been damaged.

[jay]

that would cover it.

[Stuart]

Hi,
one other site that has been big in lightning protection etc...
http://www.polyphaser.com/ppc_pen_home.asp
I had a friend that had work done in his house and the ground on his water pipe was disconnected. The lightning strike was down the street and it then came into his house and ruined his garage door opener, washing machine and two racks of ham radios.
Stuart

[JLehnert]

CBL,

Talk to the ADI people, or Guy over on CocoonTech.com. The 485/232 chips are socketed on the ocelot, so once you get a new one, it's a 5 minute switch job. ADI has been real good about shipping out the replacement chips.

[zoomkat]

To protect the data lines, I'd try putting zener diodes (or regular diodes in series) between the data lines and ground to bleed off excess voltage spikes. On an rs232 line, a 12.0v zener diode should work to prevent spikes above 12v on the line.

[wpiman]

My mother always told me to unplug the TV during a big storm.

[Rick Tinker]

zoomkat's idea is not too bad if it works - sort of makes sense that it might work.

I too had a unit go bad after a storm last year, and then just yesterday I had a near scare. My IR was not working and other sensors - went to the basement (wire central) and found the COMMS light was not flashing. I thought for sure another '485 chip had fried. I am certain that the static electricity from a nearby lightning hit comes in over the wiring running through the house (I only have about 3 miles of copper in here) Either that, or the IR sensors got overloaded and were actually able to transmit the electrical equivelent of a "too bright" IR signal it received from the lightning into the box where it scrambled things.

Either way, I was relieved when I turned off the power, waited a few seconds, and turned it back on to find it working normally again.

I tried the socket replacement 485 chip on the previous unit and it did not fix it, so it is not always that.

If my theory is correct though, the various grounding solutions will not help as the static discharge comes in over the data lines, not the power.

[kenm]

You may want to look at the opto-isolation devices available at B&B Electronics. There are probably several companies making similar products but these are the guys I've used for several years.

http://www.bb-elec.com

Ken