Lightning taking out Ethernet anecdotes

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From: Phill Kelley

Hi Adam,

I picture you as being on the receiving-end of tons of email so I'm always leery of dashing-off a quick message and adding to your load. However, your article about Ethernet problems after a power surge is reminiscent of my own similar experience.

After a surge, my Network prefs showed my Ethernet port but it was grayed out. Fiddling with cables and restarting couldn't bring it back to life. When I tried to create a new location, the port wasn't even on offer. I was on the point of declaring the motherboard port dead when it occurred to me to try one last thing: resetting the PRAM. In these heady days of Mac OS X, zapping the PRAM isn't something we tend to do much but in older times that and rebuilding the desktop were de rigueur debugging, right?

[FYI, zapping the PRAM didn't help me - I forgot to mention that I'd tried that. -Adam]

Once I zapped the PRAM, my Ethernet port returned to service. As did my modem port which, at that point, I hadn't even realized had also been affected by the surge. You didn't discuss your forensic methods in your article so, for all I know, you have already tried the PRAM. However, on the off-chance that you haven't, you may wish to give it a whirl and see what happens.

Also, there is another thing to be wary of with third-party Ethernet NICs. It has been my experience that many of them lack the circuitry that Mac OS X depends on to sense cable-unplugged. That, in turn, breaks the automatic re-routing to alternative ports. If you have multiple network interfaces in your G4 and rely on auto re-routing, you may also wish to check that it still works with your new NIC.

Regards, Phill

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From: Ted Johnson

Thought I'd pass on this info. I've also lost my card on two computers, one an iMac, which necessitates replacement of the motherboard, and a Quicksilver tower which can have a card replaced. All the computers and peripherals were on surge protectors. All the surge protectors were unplugged from the wall.

The hub for the cable ethernet however, was inadvertently left plugged straight into a wall outlet. The electric spike came through the ethernet cable and blew out two cards. It left two others unharmed. No explanation for that!

The hub was/is fine. The hub was "powered" by a transformer (brick) and the electric spike came through the outlet and through the hub and then through the cables to the computers. Classic "back door situation)! Three computers were connected to the network at the time, but it only took out two of them. There wouldn't have been a complete circuit through any of the computers (as they were all unplugged) which normally would mean no flow of current, but in the case of a big spike, I'm not sure how it would work. I don't know how the ethernet card is isolated within the board proper either, but since nothing else was hurt, I going to assume that it took out something very fast in the card itself, which isolated the remainder of the card and mother board and protected them. I looked at the board, but saw no obvious signs of a burnt resistor or whatever, so couldn't go any further with it.

It took out the card on a Slate iMac, and same for a Quicksilver 800 tower. With the tower I simply bought a plug-in card and it works fine since. With the iMac, because of the cost of a new motherboard plus labor, I'm just using it without the ethernet but it's awkward. Can't connect to the www of course, or to a network, but there are workarounds and I can keep it updated and use it for everything else. We have gotten into the habit of turning off the surge protectors (which are hooked up in series where a lot of connections are needed) and then unplugging them entirely from the outlet. Nonetheless, we rarely unplug the cable modem/router surge protector as it's in a different location then the computers, so we're still open to the possibility of another hit, though now we're sure all is on the surge protector. We do unplug that one too when there's a big storm.

Thanks for the news magazine. I always look forward to receiving it.

Ted Johnson

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From: Smith Kennedy

Another low-cost option I became aware of several years ago (can't remember where) is any 10/100 NIC using the RealTek RTL8139 chipset. I actually found one about 2 years ago at CompUSA, and guessed it had an RTL8139 chipset by looking at the picture of the card on the box. It was $12. Its box claimed no Mac OS compatibility, but there are both Mac OS 9 and Mac OS 10.2.x drivers available on the chipset manufacturer's Web site here for download:

<http://www.realtek.com.tw/downloads/downloads1-3.aspx?series=16&Software=True#16Others>

[Yes, I was aware of the RealTek drivers, but I didn't want to get into a situation with needing an update to them when I upgraded to Tiger or some other OS version. -Adam]

Just a little FYI - thanks for the TidBITS!

Smith

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From: Charles Bouldin

I have twice lost ethernet equipment at our house due to lightning. The first time I lost 4 ports on a 16 port 10/T hub; the 2nd time was very much like your case. Lightning struck about 80 feet from the house, blowing the bark off a 20 foot section of a large tree and killing the motherboard ethernet on my g4/400 (which has since been retired). My solution was the same as yours, a PCI ethernet card.

I just wanted to add that Ethernet is THE overlooked vulnerability in lightning damage for computers. When I looked into it several years ago, it was hard to find surge suppressors that included ethernet (although nearly all of them included a phone wire connection). Nowadays, however, APC and other vendors have ethernet surge suppressors, as stand-alone units or built into UPS systems.

I got a two-layered system: A whole house suppressor that goes on the fuse box and several inline ethernet surge suppressors that go near switches and individual computers. Also, while wireless may be slower, it is utterly immune to this issue.

[When I mused that I wasn't sure how the Ethernet protectors worked, Chuck sent the following reply. -Adam]

Well, my understanding is that the ethernet cable acts as the antenna that couples the EMP from the lightning straight into your ethernet. Since the ethernet controller chip is the first device of any complexity that gets hit by the surge, that is what blows. In fact, it wouldn't surprise me too much if that wasn't intentional.....better to lose an ethernet port or two than the whole motherboard/computer.

There are two nearly complete solutions to this issue: Wireless, as you pointed out, or, fiber networks instead of copper. A friend of mine who does network installs tells me that he --never-- runs Cu wire between buildings, only fiber, because every single time he has run Cu, no matter how it was protected, isolated, etc, he has gone back within a year or two to replace things due to lightning damage.

Chuck Bouldin

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At 2:00 am -0700 24/7/04, <tidbits-talktidbits.com> wrote:
>--- begin forwarded text
>
>From: Charles Bouldin
<snip>
> A friend of
>mine who does network installs tells me that he --never-- runs Cu
>wire between buildings, only fiber, because every single time he has
>run Cu, no matter how it was protected, isolated, etc, he has gone
>back within a year or two to replace things due to lightning damage.

There is a danger other than lightning with running copper between
properties (at least in the UK).

The mains electricity in the UK is 3 phase, and adjacent properties
are on different phases (although some businesses will have full 3
phase supplies). Consequently, if there was an electrical fault, it
would be possible for the copper joining the buildings to result in
double the standard voltage - 440V in the UK.

You shouldn't really link buildings on different mains supplies with
copper. Optical or radio are safer links.

Cheers,

Joel
--

Joel Smith
Dales IT Ltd
22 Springfield Way
Pateley Bridge Tel: +44 1423 712591 Mobile: +44 7768 803758
N.Yorks HG3 5PA Fax: +44 870 1617192

> [When I mused that I wasn't sure how the Ethernet protectors worked,
> Chuck sent the following reply. -Adam]
>
> There are two nearly complete solutions to this issue: Wireless, as
> you pointed out, or, fiber networks instead of copper. A friend of
> mine who does network installs tells me that he --never-- runs Cu
> wire between buildings, only fiber, because every single time he has
> run Cu, no matter how it was protected, isolated, etc, he has gone
> back within a year or two to replace things due to lightning damage.

Yes, I remember reading in a electrical engineering trade journal (many
years ago) that it is fairly common for lighting strikes to travel through
the ground for quite some distance and to enter wires (even shielded wires)
run between buildings and cause surges and spikes on both ends of the
cables.

Also it is possible for 2 buildings to be at different ground potentials
(different soil conditions can make one area have a ground several volts
over a different region.) Because of this signals between the buildings
can be poor and cause lots of errors. This generally more true in widely
separated buildings, but even a nearby building may a poor or degraded
ground connection causing problems.

Fiber and wireless are usually the better way to go between buildings.

On Jul 23, 2004, at 20:57, Ken Workman wrote
> Well, my understanding is that the ethernet cable acts as the antenna
> that couples the EMP from the lightning straight into your ethernet.

Does this mean you need surge suppressors attached to every Ethernet
port? And is there a length below which the cables are safe from EMP?

--
Chris Page - Software Wrangler - Dylan Pundit

This is on a slightly different vein with dual Ethernet, so Adam you
may want to change the subject. My home webserver/mailserver is about
to become my backup server in the last step from replacing my
now-defunct 7500 with a Sawtooth tower. Should I buy a second Ethernet
card and run all external connections (and my router's DMZ) into one
card while keeping the other Ethernet port for the LAN? Would that
increase my security? I'm concerned about Apple file sharing on my LAN
since I never contact my server from any other means than SSH or
Timbuktu. Right now the LAN and WAN share the same port so I can't
close Apple file sharing on my server. Am I overly concerned with
leaving file sharing open to the world?

<http://db.tidbits.com/getbits.acgi?tbart=07737>

Evans