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Old 04-16-2009, 03:41 PM
 
73 posts, read 118,703 times
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Has any ever had this experience: We had a pretty bad thunderstorm last Friday night. When everyone got to work Monday 3-4 ports in a 16-port switch were dead. A HP laserjet 4240n ethernet port would no longer function, one pc's network card was shot, ports from two other small hubs were blown. An HP 6310 printer with ethernet port was shot.

I guess my question is has anyone ever had something similar happen? My hypothesis is that the facility was hit by lightening but it ran through the cat-5 cables of the lan, not the electrical circuits.


Am I nuts or what.
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Old 04-16-2009, 04:21 PM
 
Location: Somewhere in northern Alabama
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It is an issue that is fairly common, and was a major problem in RS-232 lines between buildings.

When you have a networked system in an environment where there is lightning, you want to have a single common ground if at all possible, and you want surge protection on all computers. Sometimes that isn't possible and isolation can be a better solution. For example a wireless network can safely use different ground points.

What wipes out stuff can be "ground loops" where a voltage is occuring between two different grounds. An easy way to visualize this is to think of two ground rods stuck in the ground 1000 yards apart. Lightning strikes near the first rod. Because of the natural resistance of the soil, the ground is more highly charged near the struck ground rod than the other. If there is a ground wire connecting the two rods, there will be a significant current racing along it to get to the lower potential area. If there is an above ground circuit, such as a power line or network line, it too can have varying voltages.

Another issue is that of induced currents. TV antennas are not physically connect to the television station, yet develop an induced small current in the highly tuned elements of the antenna array. Similarly, any wiring near a lightning strike will have a small current induced in it. Lighting modulates across a wide band of the RF spectrum so the chances of one or more of the pulses finding a tuned length of wire is quiet high. That induced current can wipe out small electronics and act in unpredictable ways.

A further issue is that the lightning, being very high in voltage and at various frequencies can go odd places. The surface of a linoleum floor is not normally a conductor, but there have been events where an unplugged X-ray machine on a linoleum floor was damaged by lightning even though it was not hit directly.
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Old 04-16-2009, 06:32 PM
 
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Lightening can get in however it wants, and destroy what ever it wants. I had a customer that had the flag pole in front of the building struck, and it took out their Cisco Router, CSU/DSU, part of the PBX, and a few stray printers or workstations.
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Old 04-22-2009, 10:39 AM
 
73 posts, read 118,703 times
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Quote:
Originally Posted by Asheville Native View Post
Lightening can get in however it wants, and destroy what ever it wants. I had a customer that had the flag pole in front of the building struck, and it took out their Cisco Router, CSU/DSU, part of the PBX, and a few stray printers or workstations.
Yes I understand this, but in this case nothing "electrical" was damaged, as in monitors. calculators or anything of this nature. Only thing zapped was network related as in network cards and certain ports of hubs and switches.
For example one HP 4240n printers built in print server got zapped but still works fine using USB or a parallel print cable.
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Old 04-22-2009, 12:05 PM
 
16,308 posts, read 25,271,830 times
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Quote:
Originally Posted by atheist SC View Post
Yes I understand this, but in this case nothing "electrical" was damaged, as in monitors. calculators or anything of this nature. Only thing zapped was network related as in network cards and certain ports of hubs and switches.
For example one HP 4240n printers built in print server got zapped but still works fine using USB or a parallel print cable.
Typically lightening "gets in" through power, but it sure sounds like it 'got in' through your network wiring somehow, thus the damage to network devices.
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Old 08-04-2017, 02:21 PM
 
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There are a lot op people who have the bad assumption that lightning has to "get in" via a physical wire that leads through a wall to the outside. THAT IS NOT THE ONLY WAY!
I lose network ports frequently in my small office. Each PC has it's own APC Backups unit. The two rooms are both on the same circuit breaker, there is a 15 foot network cable that goes from the router in one room, where there a PC and printer, over to the opposite corner through interior wall to the other room over to a switch with three more PCs. A couple times a year, there's a nearby lighting (NOT DIRECT) that induces a surge in that 15 foot network wire. It takes out the ports it's plugged into on both sides. Since I have extra ports, I just move the wire on both ends to another port, and everything's good to go. Occasionally, it will also take out the ports on another 8 foot wire that connects the switch to the PC in that same room. When I run out of ports on a router or switch, I just pull out the spare and replace that network device.

These network ports can be damaged even when we've unplugged everything from the wall. Our internet is not even connected to the outside. We have a wireless LTE modem in one room near the window. That one has a short CAT5 cable, only 3 foot, and we've never lost that port. It's always the ports connected to longer CAT5 cables.

Simple physics, Electro Magnetic Field induces charge in parallel wire. Lightning is such high power, that even wire that's off like 45 degrees will still induce sufficient surge power to blow those ports. All ports have some built in surge protection, there's so many small surges that you don't notice, and eventually that protection breaks down and you lose a port/device.

Grounded shielded wire can help in this case, as the shield gets most of the induction on it, and safely sends it to ground. Trouble is, many ports are not designed to use shielded wire and don't benefit from it.
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Old 08-04-2017, 03:44 PM
 
Location: Cleveland, Ohio
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My old house was struck by lightning. The lightning rod thing by the chimney took the brunt. Bricks from the chimney rained down on the car. One port on my router was fried. The network card in my PC was fried. And that's it. Router still worked with other ports.
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Old 08-05-2017, 12:43 AM
 
Location: Somewhere in northern Alabama
18,564 posts, read 55,493,012 times
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Quote:
Originally Posted by javaman97 View Post
There are a lot op people who have the bad assumption that lightning has to "get in" via a physical wire that leads through a wall to the outside. THAT IS NOT THE ONLY WAY!
I lose network ports frequently in my small office. Each PC has it's own APC Backups unit. The two rooms are both on the same circuit breaker, there is a 15 foot network cable that goes from the router in one room, where there a PC and printer, over to the opposite corner through interior wall to the other room over to a switch with three more PCs. A couple times a year, there's a nearby lighting (NOT DIRECT) that induces a surge in that 15 foot network wire. It takes out the ports it's plugged into on both sides. Since I have extra ports, I just move the wire on both ends to another port, and everything's good to go. Occasionally, it will also take out the ports on another 8 foot wire that connects the switch to the PC in that same room. When I run out of ports on a router or switch, I just pull out the spare and replace that network device.

These network ports can be damaged even when we've unplugged everything from the wall. Our internet is not even connected to the outside. We have a wireless LTE modem in one room near the window. That one has a short CAT5 cable, only 3 foot, and we've never lost that port. It's always the ports connected to longer CAT5 cables.

Simple physics, Electro Magnetic Field induces charge in parallel wire. Lightning is such high power, that even wire that's off like 45 degrees will still induce sufficient surge power to blow those ports. All ports have some built in surge protection, there's so many small surges that you don't notice, and eventually that protection breaks down and you lose a port/device.

Grounded shielded wire can help in this case, as the shield gets most of the induction on it, and safely sends it to ground. Trouble is, many ports are not designed to use shielded wire and don't benefit from it.
What you describe is possible but unlikely. If the printer is not surge protected, or if the monitors are not protected, you can get as you describe. My guess is if you throw a surge protector on that breaker panel box, and verify the ground is solid, you may resolve the issue. EVERYTHING in the networked system has to be surge protected or the whole thing is at risk.
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Old 08-05-2017, 07:20 AM
 
Location: Southeastern North Carolina
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At my house last year, lightning fried my modem/router combo, and the ethernet card in the desktop PC that it was connected to. Also fried was the booster for my rooftop TV antenna.

The computer and modem were plugged into a surge protector when this happened. I upgraded my surge protectors after that, hopefully the new ones will do a better job.
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Old 08-06-2017, 09:43 AM
 
138 posts, read 120,512 times
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Quote:
Originally Posted by Ellise View Post
The computer and modem were plugged into a surge protector when this happened. I upgraded my surge protectors after that, hopefully the new ones will do a better job.
Protectors adjacent to an appliance do not even claim to protect from typically destructive surges. Those only claim to protect from surges typically made irrelevant by what is already inside appliances. Worse, those plug-in protectors can sometimes compromise what is better protection inside that appliance.

Some numbers since most who recommend never discuss specification numbers. A protector adjacent to an appliance must either 'block' or 'absorb' a surge. How does its 2cm protector part 'block' what three miles of sky cannot? How many joules does that protector claim to absorb? How does it 'absorb' a destructive surge - maybe hundreds of thousands of joules? A surge to tiny to destroy an appliance can even destroy a protector. Then a naive consumer uses wild speculation to assume, "My protector sacrificed itself to save my appliance." Nonsense. That appliance saved itself. Wild speculation creates a junk science conclusion.

Move on to how protection was always done - even 100 years ago. A surge that is harmlessly absorbed outside is then not anywhere inside the building. Once inside, then nothing (no plug-in protector) can avert what is only a destructive hunt for earth ground.

That surge would be incoming to everything. Is everything damage? Of course not. It is electricity. That means it must have both an incoming and and outgoing path. In your case it found a best outgoing path via modem/router combo, ethernet card, and a TV antenna booster. So it need not overwhelm protection in other appliances.

How do you protect everything? Give a surge a low impedance (ie less than 10 foot) connection to earth ground BEFORE it can enter. Then it need not hunt for earth destructively inside. This 'whole house' protection comes from other companies know for integrity including Intermatic, Square D, Ditek, Siemens, Polyphaser (an industry benchmark), Syscom, Leviton, ABB, Delta, Erico, General Electric, and Cutler-Hammer (Eaton). Was your protector manufactuer listed?

No protector does protection. Not one. Effective protection (from companies of integrity) means a low impedance (ie hardwire has no sharp bends) connection to what harmlessly dissipates hundreds of thousands of joules: single point earth ground. All four words have electrical significance. That least expensive and easy solution even protects near zero joule protectors and lesser joule UPS.

If anything needs protection, then everything needs that protection. Learn from your mistake.

Now some more numbers. A direct lightning strike can be 20,000 amps. So a minimal 'whole house' protector is 50,000 amps. This costs about $1 per protected appliance. Like all effective protectors, it remains functional for decades after many direct lightning strikes. And it has what any effective protector must always have - a low impedance (ie less than 10 foot) connection to earth.

As you can see, much to learn and to unlearn. Protection is always about where hundreds of thousands of joules are harmlessly absorbed. A protector is only as effective as its earth ground. Then best protection already inside every appliance is not overwhelmed.
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