• Ethernet and power surges (thunderstorms)

    From Daniel James@21:1/5 to All on Sun Sep 25 12:02:19 2016
    For ease of cabling, we have a length of Cat5e cable that runs around
    the *outside* of part of the house. There's a wall box at each end, one
    of which is connected by a patch cable to the ADSL router, the other to
    an ethernet switch. The cable is just a length of Cat5e run through
    holes in the brickwork and stapled to the wall of the house by a
    helpful local builder.

    In the recent storms that cable seems to have picked up a charge that
    damaged the ADSL router and possibly also the switch, but (fortunately)
    nothing else.

    The ethernet port on the router that was connected to the external
    cable is dead (the others are fine) and the ADSL connection is dead,
    though the router itself and the built-in WiFi are still working.

    There was no lightning strike, but the storm was directly overhead and
    very active. I can well imagine that it might have induced a sufficient
    current in the external cable to damage the connected kit.

    What can I do to reduce the likelihood of this happening again? Should
    I install metal sheathing around the external cable? I see that one can purchase ethernet surge protector devices, are these any good?

    What does the team think?

    --
    Cheers,
    Daniel.

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  • From Adrian Caspersz@21:1/5 to Daniel James on Mon Sep 26 12:12:59 2016
    On 25/09/16 12:02, Daniel James wrote:
    For ease of cabling, we have a length of Cat5e cable that runs around
    the *outside* of part of the house. There's a wall box at each end, one
    of which is connected by a patch cable to the ADSL router, the other to
    an ethernet switch. The cable is just a length of Cat5e run through
    holes in the brickwork and stapled to the wall of the house by a
    helpful local builder.

    In the recent storms that cable seems to have picked up a charge that
    damaged the ADSL router and possibly also the switch, but (fortunately) nothing else.

    The ethernet port on the router that was connected to the external
    cable is dead (the others are fine) and the ADSL connection is dead,
    though the router itself and the built-in WiFi are still working.

    There was no lightning strike, but the storm was directly overhead and
    very active. I can well imagine that it might have induced a sufficient current in the external cable to damage the connected kit.

    What can I do to reduce the likelihood of this happening again? Should
    I install metal sheathing around the external cable? I see that one can purchase ethernet surge protector devices, are these any good?

    Go fibre?

    Does any of your switching kit take mini-GBIC transceiver modules? Cheap
    on eBay. I paid £5 for a couple once on eBay and have laid fibre outside mindful of the same issues with lightning.

    --
    Adrian C

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  • From Daniel James@21:1/5 to Adrian Caspersz on Mon Sep 26 13:15:29 2016
    In article <e4se5sFhiueU1@mid.individual.net>, Adrian Caspersz wrote:
    Go fibre?

    That's an interesting idea -- would certainly address the issue of susceptibility to lightning, etc. -- but I'm not sure I'd know how.

    Does any of your switching kit take mini-GBIC transceiver modules?

    Nope (I had to look up mini-GBIC). So-called RJ-45 sockets only. The
    router is a Draytek Vigor2860ac (the one clobbered by the lightning was
    a 2860n, but I took the opportunity to upgrade as we have some 5GHz
    devices around the place) and the switch is bog standard Netgear
    100Mbps thing.

    Sounds like significant expenditure would be required to add fibre
    capability here?

    --
    Cheers,
    Daniel.

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  • From Adrian Caspersz@21:1/5 to Daniel James on Mon Sep 26 18:07:37 2016
    On 26/09/16 13:15, Daniel James wrote:
    In article <e4se5sFhiueU1@mid.individual.net>, Adrian Caspersz wrote:
    Go fibre?

    That's an interesting idea -- would certainly address the issue of susceptibility to lightning, etc. -- but I'm not sure I'd know how.

    Does any of your switching kit take mini-GBIC transceiver modules?

    Nope (I had to look up mini-GBIC). So-called RJ-45 sockets only. The
    router is a Draytek Vigor2860ac (the one clobbered by the lightning was
    a 2860n, but I took the opportunity to upgrade as we have some 5GHz
    devices around the place) and the switch is bog standard Netgear
    100Mbps thing.

    Sounds like significant expenditure would be required to add fibre
    capability here?


    Not really. Upgrade your switch :)

    For work, I've a couple of cheapish managed switches with mini-GBIC, a
    24-port fanless gigabit TP-Link TL-SG2424 and an old noisy Linksys
    SRW208P which lives next to an even noisier server.

    The TP-Link was about £100 new and the linksys was scored from a car
    boot sale for peanuts, is 10/100 and gigabit for a couple of ports.

    A length of OM1 fibre with premade LC-LC connectors was about £20.

    --
    Adrian C

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  • From gargoyle60@21:1/5 to Stephen on Tue Sep 27 10:45:28 2016
    On Mon, 26 Sep 2016 20:51:07 +0100, Stephen <stephen_hope@xyzworld.com> wrote:

    I have seen some of the electronics on a device taking a "near miss"
    to be vaporised on the circuit board.

    Years ago a nearby lightning strike knocked out my old dial-up modem along with those of all my
    neighbours, even though the stike didn't hit any telephone poles.

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  • From Daniel James@21:1/5 to Stephen on Tue Sep 27 13:45:26 2016
    In article <ustiub5japj3m9f7fp4p253u2a88nbsbui@4ax.com>, Stephen wrote:
    You were lucky - the energy involved in an actual strike is sufficient
    to vaporise the cable.....

    Unlucky to be affected at all ... lucky it wasn't worse. <shrug>

    A nearby strike will involve a heavy current through to "ground" which
    can make for a large change in the ground voltage - this is 1 reason
    it isnt a good idea to shelter under a tree in a lightning storm.

    Yes, I'm aware of the physics behind it. I'm just hoping for practical
    advice on how to minimize the damage the impact of this happening again.

    If you want to shield a metal cable then the shield needs to be set up
    such that it doesnt just channel induced current into the cable and
    cause damage that way.

    That's a good point ... and putting the external cable in a shielded
    conduit of some sort would very likely make the conduit itself act like
    a lightning conductor, and increase the risk to the equipment.

    Mind you, there's more chance of loss from a strike on the TV aerial on
    the roof blowing up the set in the living room (which didn't happen).

    Maybe accepting the risk and the occasional device replacement will be cheapest.

    That's certainly an option! Thanks for your thoughts.

    --
    Cheers,
    Daniel.

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  • From Stephen@21:1/5 to All on Mon Sep 26 20:51:07 2016
    On Sun, 25 Sep 2016 12:02:19 +0100, Daniel James <daniel@me.invalid>
    wrote:

    For ease of cabling, we have a length of Cat5e cable that runs around
    the *outside* of part of the house. There's a wall box at each end, one
    of which is connected by a patch cable to the ADSL router, the other to
    an ethernet switch. The cable is just a length of Cat5e run through
    holes in the brickwork and stapled to the wall of the house by a
    helpful local builder.

    In the recent storms that cable seems to have picked up a charge that
    damaged the ADSL router and possibly also the switch, but (fortunately) >nothing else.

    You were lucky - the energy involved in an actual strike is sufficient
    to vaporise the cable.....

    I have seen some of the electronics on a device taking a "near miss"
    to be vaporised on the circuit board.

    have a look at the various lightning protection codes.

    http://lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf


    The ethernet port on the router that was connected to the external
    cable is dead (the others are fine) and the ADSL connection is dead,
    though the router itself and the built-in WiFi are still working.

    There was no lightning strike, but the storm was directly overhead and
    very active. I can well imagine that it might have induced a sufficient >current in the external cable to damage the connected kit.

    A nearby strike will involve a heavy current through to "ground" which
    can make for a large change in the ground voltage - this is 1 reason
    it isnt a good idea to shelter under a tree in a lightning storm.

    The effect reduces rapidly as you get further from the strike.

    if devices are grounded at different places with 1 closer to a "close"
    strike, the resulting current flow can cause damage.

    You can get related spikes coming in through external cable, power or
    phone lines

    What can I do to reduce the likelihood of this happening again? Should
    I install metal sheathing around the external cable? I see that one can >purchase ethernet surge protector devices, are these any good?

    What does the team think?

    Ethernet already has twisted pairs & insulated transformers included
    to limit interference and that will help.

    I suspect non metallic protected fibre is the ideal way to go since
    this is how building to building LAN cabling is done by default.

    it wont shield the devices at each end from power line surges, but at
    least they will not have a ground spike on 1 but not the other causing
    a current through the connecting cable.

    If you want to shield a metal cable then the shield needs to be set up
    such that it doesnt just channel induced current into the cable and
    cause damage that way.

    Maybe accepting the risk and the occasional device replacement will be cheapest.
    Stephen Hope stephen_hope@xyzworld.com
    Replace xyz with ntl to reply

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  • From Daniel James@21:1/5 to Andrew Gabriel on Mon Nov 21 23:55:26 2016
    In article <o0vef9$tgq$1@dont-email.me>, Andrew Gabriel wrote:
    I would not discount the possibility the pulse came in on the phone
    line. 5-10km line to the exchange is probably 1000x more likely to
    pick up a spike than 10m of wire around your house.

    It's true that the damaged parts are all in the path between the phone
    line and the external ethernet cable, but there is a surge protector
    between the phone socket and the router and that *should* have blown
    before the equipment itself.

    That's one of the things that prompted me to look into surge protectors
    for ethernet before I started this thread.

    --
    Cheers,
    Daniel.

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  • From Andrew Gabriel@21:1/5 to Daniel James on Mon Nov 21 18:30:01 2016
    In article <VA.00000bd0.04373403@me.invalid>,
    Daniel James <daniel@me.invalid> writes:
    For ease of cabling, we have a length of Cat5e cable that runs around
    the *outside* of part of the house. There's a wall box at each end, one
    of which is connected by a patch cable to the ADSL router, the other to
    an ethernet switch. The cable is just a length of Cat5e run through
    holes in the brickwork and stapled to the wall of the house by a
    helpful local builder.

    In the recent storms that cable seems to have picked up a charge that
    damaged the ADSL router and possibly also the switch, but (fortunately) nothing else.

    The ethernet port on the router that was connected to the external
    cable is dead (the others are fine) and the ADSL connection is dead,
    though the router itself and the built-in WiFi are still working.

    There was no lightning strike, but the storm was directly overhead and
    very active. I can well imagine that it might have induced a sufficient current in the external cable to damage the connected kit.

    What can I do to reduce the likelihood of this happening again? Should
    I install metal sheathing around the external cable? I see that one can purchase ethernet surge protector devices, are these any good?

    What does the team think?

    I would not discount the possibility the pulse came in on the phone
    line. 5-10km line to the exchange is probably 1000x more likely to
    pick up a spike than 10m of wire around your house.

    --
    Andrew Gabriel
    [email address is not usable -- followup in the newsgroup]

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