How to prevent damage to my LAN card due to lightning?

[Wrichik Basu]

TL;DR Summary

Is there anything I can do to protect the LAN card from lightning strikes?

This is the second time lightning has damaged the LAN card in our desktop. I am yet to get my hypothesis verified by the ISP, but the indications are exactly the same as last time: the computer cannot recognize the LAN adapter. Previously, when the connection had problems, we could see the LAN adapter with a cross sign beside it in the Network and Sharing Centre (Win 7 Pro). This time I cannot see any adapter, so I am guessing it is the LAN card that is damaged.

This time, instead of buying an internal LAN card, I was thinking of getting an Ethernet to USB adapter, like this one.

Is there anything I can do to protect the LAN card from lightning strikes?

 

[jedishrfu]

Use wifi and router instead, and properly isolate your power supply.

 

[Wrichik Basu]

Use wifi and router instead, and properly isolate your power supply.

Is the LAN card being damaged due to surges in the power supply? Shouldn't the SMPS be damaged in that case? Note that the PC was switched off at that time.

 

[jim mcnamara]

The answer lies in the nature of what is referred to as an EMP ( Electro Magnetic Pulse). Lightning is a very high voltage discharge with an extremely high current. ... A lightning strike produces a localized EMP that gives rise to large electrical currents in nearby wires. Including the wiring inside your PC, past the mains switch.

@berkeman or @Baluncore would be likely to know how to prevent it. Cheaply ...I hope.

 

[jim mcnamara]

Just for fun - think of an hours-long EMP-kind of effect. The Carrington Event comes to mind - the result of a powerful solar flare (CME) hitting Earth dead-on, a geo-magnetic storm.

Very interesting read, especially for folks like @anorlunda or anyone else who knows Reddy Kilowatt (my avatar):

https://en.wikipedia.org/wiki/September_1859_geomagnetic_storm

 

[Baluncore]

berkeman or Baluncore would be likely to know how to prevent it. Cheaply ...I hope.

There are low cost ways that might work, without modifying the circuits.

Search eBay for; Noise Suppressor EMI RFI Clip Choke Ferrite Core Cable Filter
Clip one onto the LAN cable.
You might also do the same to the power cables.

That will prevent fast common-mode transients traveling along the cable, but will allow the high speed differential data signals to pass. The inductance should slow the induced transient to a slew rate that can be handled by the protection on the card.

 

[Wrichik Basu]

Search eBay for; Noise Suppressor EMI RFI Clip Choke Ferrite Core Cable Filter
Clip one onto the LAN cable.
You might also do the same to the power cables.

Found this one on Amazon India. Will buy it along with the LAN card.

 

[Nik_2213]

IIRC, you can get in-line spike-catchers, intended for protecting eg IPCAMs. Like a Cat-cable connector, but with varistors etc. Akin to 'mains' spike-catchers, but at Cat-voltages. IIRC, they may be available for POE systems, too.
The *serious* versions have a grounding 'tail' which, like a radio-ham's aerial spark-gap 'tail', must be very well earthed...

 

[sysprog]

Reddy Kilowatt Finds an Outlet​

 

[Vanadium 50]

I don't think this is lightning EMP. I think lightning in India is the same as lightning in Europe or North America, and there are huge network installations in office buildings that do just fine in thunderstorms. (That said, I had a lightning strike that took out a printer and a TV...and a good chunk of roofing and masonry)

What is different is the electrical grid. I suspect you will do better with power conditioning than anything on the LAN cable side.

 

[anorlunda]

If your LAN card is powered by your computer's power supply, then a surge in the AC power lines is more likely to damage the power supply than the LAN card. So let me ask: Is it only the LAN card that is getting damaged?

• If no, then you should look at protecting the whole house. Surge protection at the electric service entrance is possible. From your past posts, I know that you experience many power quality problems.
• If yes, then perhaps it is the in-house data wiring, not the power wiring that is picking up surges induced by nearby lightning. Changing to WIFI instead of a LAN eliminates long wires.

I agree that EMP is not likely as the source of your problems. But EMP versus induced current makes little practical difference. My boat was hit by lightning. I lost my radar, SSB radio, and a hand-held-battery-powered radio. It had to be EMP that fried the hand-held device, but it could have been induced surges in the external power and signal wires that fried the radar and SSB. It made no difference to me; all three were fried.

 

[Wrichik Basu]

Is it only the LAN card that is getting damaged?

Yes.

Changing to WIFI instead of a LAN eliminates long wires.

But the router still has the possibility of getting damaged, right? The advantage of using a router, however, is that motherboard will never be exposed to the surge.

 

[anorlunda]

But the router still has the possibility of getting damaged, right?

Yes that's possible, but short wires pick up less surge from lightning than long wires.

Using coax cable, or twisted pair wires also helps, but having no long wires is best.

If is only the LAN getting damaged, then I think you need to focus on the signal or data wiring, not the power lines.

 

[Tom.G]

There is such a thing as shielded Ethernet cable. The usual cable is type UTP for Unshielded Twisted Pair, the Shielded is type STP for Shielded...

I haven't it used so I don't know what the facility for grounding is. One reference stated that kits were available with metal connectors instead of the common plastic ones.

Try a Google search for 'shielded ethernet cable'

There are two scenarios if it was the lightning strike that caused the failure.

The field (electric or magnetic) induced a voltage in either (or both):

1. The data lines
2. The power system, and it could be worse if the computer and router/switch/hub were on different circuits

(side story)
Several years ago I lost a printer, apparently from a close lightning strike. There was a 100ft (30m) flag pole about 150ft (50m) away that was struck by a large lightning bolt. (LOUD!) I had surge suppressors on everything and a battery backup so no major damage. The printer could no longer be seen by the computer, but the printer passed self-test and could print a test page. I speculate the EMP was received by the serial data cable and wiped out the printer. Replaced the printer and all was good (Whew!)

Cheers,
Tom

 

[Wrichik Basu]

I forgot to mention one incident, and this might show that even the power lines had a surge. We were watching television when the lightning struck. The moment it struck, the television switched itself off, so did the set-top-box. But when we switched them on later, they were working fine.

Note that the PC was switched off when lightning struck, which is why it might have been saved. In addition, the socket where we connect the PC has inbuilt surge protection through an MOV, while the television socket does not have that.

 

[anorlunda]

Lightning effects are very diverse. They appear to be non repeatable. Given the same circumstances, every possible outcome seems to be possible with repeated tests. That makes it difficult to design protection based on anecdotes.

In addition, the socket where we connect the PC has inbuilt surge protection through an MOV, while the television socket does not have that.

MOV surge protectors have a joule rating. Every time they stop a surge a fraction of the joule capacity is "used up" when it is all gone, then they no longer protect. But there is no indication of the joule rating remaining. Unless you buy a new protector after every thunderstorm, you have no way to know if it still protects. That is very unsatisfying, but it is the reality for inexpensive MOV surge suppression protectors.

My company once contracted to test utility devices for lightning withstand ability. We did that by attaching a wire to the device, then using a rocket to lift the other end of the wire into a thunderstorm. It is called triggered lightning. We had to repeat the test many times on each type device before making a conclusion.