Re: Daisy chain wireless routers

On Dec 6, 3:52 pm, ato_...@xxxxxxxxxxx wrote:
I did say nearby, not a directlightningstrike.
The nearest estimate (from being the locallightning
sink, based on several strikes) is that the differential
between buildings is 80-100V. Some equipment
may suffer from the electromagnetic pulse acting
on ground loops.

Meanwhile BT's computers connect to overhead wires everywhere in
town. According the research papers, a telco central office may
suffer about 100 surges during every thunderstorm. So for about 5
days every summer, you are without phone service while BT swaps out
the computer? Of course not. It is routine to suffer direct strikes
and no damage. Same protection makes nearby strikes irrelevant.

But that means every wire entering the building is earthed before it
enters. Every wire is earthed to the same earth ground. That
earthing connection is made directly (hardwired) for coaxial wire. Or
via a surge protector for twisted pair. The protector without such
earthing means surge damage is expected. So facilities that must
never suffer damage learned even 100 years ago what must be made
better for no damage.

The protector is only as effective as its earth ground. Earth
ground (not a protector) determines direct lightning strike
protection. Earthing is why BT can suffer 100 surges - and no
damage. Also essential is to locate the protector distant from
electronics. A protector adjacent to electronics (and too far from
earth ground) may simply earth that surge, destructively, through
electronics.

Telcos prefer protectors to be located up to 50 meters distant from
electronics - and as short as possible to earth ground. For that
building interconnect cable, that means every wire in the cable must
make a less than 3 meter connection to earth where it enters the
building. A connection to the same earth ground electrode used by AC
electric, telephone, cable, and any other incoming wire.

It has long been routine to hook buildings together with wire and
not suffer damage. But many don't learn why. Earthing determines
whether a surge does not enter the building - does not find earth
ground, destructively, through electronic appliances. But again, this
is how its been done for 100 years. This is why BT with computers
connected to overhead wires all over town must never suffer
electronics damage. Protection is not some magic box. Protection is
defined by the earth ground. Earthing (and a protector to connect each
ethernet wire short to earth) means no damage from direct lightning
strikes.

Some protectors made effective by a short connection to earth:
http://www.keison.co.uk/furse/furse19.htm
http://www.tripplite.com/products/product.cfm?productID=153#spec
http://www.keison.co.uk/furse/furse08.htm
http://www.keison.co.uk/furse/furse07.htm

.

Relevant Pages

  • Re: Repairing Lightning Damaged Tvs
    ... > Establish the single point earth ground. ... > be a buried bare 4 AWG ground wire that interconnects AC ... > not connect to any other earthing wire until they all meet at ... > protector must connect from each wire to that bus bar. ...
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  • Re: Repairing Lightning Damaged Tvs
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  • Re: Soon to arrive my HDTV
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  • Re: Lightning and computer?
    ... Impedance is determined by wire length, number of sharp bends, ... house' protector installed by the telco. ... A protector is only as effective as its earth ground. ...
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  • Re: surge protectors
    ... 40 annually to the WTC - and electronics not ... this is about a nearby lightning strike to a long wire antenna. ... You did not see protector devices inside the blender? ... As described in another post is wire impedance. ...
    (alt.home.repair)
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