[c-nsp] Surge protection on leased lines

Thu Sep 4 22:52:41 EDT 2008

Here is an explanation of what your SUPPOSED to have:

http://www.cermetek.com/Support/APP-Notes/611-0175.pdf

with some schematics in case you want to roll your
own protectors.

According to this, per FCC part 68, your national telephone
company is in violation of FCC regs if it is not providing
an isolation barrier at the customer handoff, which clearly
it is not if your losing WICs to lighting.  They may be sliding
under the regulation by giving you the handoff via V.35
but I doubt it.  Frankly I've never
seen a SHDSL line being handed off to the customer on a
V.35.  I've seen plenty of Telco-owned muxes that took a
T1 or SHDSL and handed off to the customer via both POTS and V35,
though, but I don't see the point of an NIU that goes from
SHDSL to V.35 - it's extra cost for the Telco, and that would
require the customer prem equipment to be sitting next to the
Dmarc since your not going to run V.35 a hundred or so feet
from the dmarc to the network room.  This scheme sounds cockamamie
to me.  You learn something new every day.

If I were you I would call your local municipality on this.
All the electrical codes I've ever seen require the utility
side of any feed into a building to have a solid, low-resistance
ground at the entry point.  They cannot just connect to a
cold water pipe or some such nonsense, they have to
drive a copper rod into the ground and ground to that.
The fact that your "national telco" is allowing lightning
energy to come into your building is a fire hazard and I
am quite sure is in violation of your local wiring codes.
They need a sold ground and suppression such as varistors
connected between that ground and both wires of the pair
that the SHDSL line is on.  If you can get the specific
code requirements for your municipality you can threaten
to report your national telco to both the FCC and the
local municipality if they do not install surge suppression.

Ted

PS  I am assuming your in the US, here.

> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net]On Behalf Of jp
> Sent: Thursday, September 04, 2008 9:01 AM
> To: Brian Turnbow
> Cc: Cisco Mailing list
> Subject: Re: [c-nsp] Surge protection on leased lines
>
>
> Usually our Telco has gas/carbon arrestors at the NID and they differ
> for pots or T1 as T1 is higher voltage.
>
> Make sure your nid, smartbox, router are all grounded together and to
> the electrical system ground. I suspect they are not if current is
> flowing in and damaging your wic.
>
> I know APC made some ptel series arrestors for T1/ISDN usage for
> protecting the twisted pairs when the rj45/48 interfaces are used. I
> have these and they are good. Too bad you don't have access to that.
>
> On Mon, Aug 25, 2008 at 06:05:07PM +0200, Brian Turnbow wrote:
> > Thanks for the response.
> > They are external csus but they are "telco property" and they
> don't want us to touch them.
> > We have asked several times that they install  protection
> coming into the building but no go...
> > They install a remote powered integrated shdsl modem/csu in an
> all plastic housing and the only place we
> > Have been able to connect a ground is to the v.35 mount on the
> integrated csu. No help there.
> > Lighting strike= burned modem/csu= burned wic
> > The v.35 protector would be a try to at least save our wic
> cards and costs of dispatching a Tech
> > for every passing storm.
> >
> >
> > Brian
> >
> > -----Original Message-----
> > From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Jay Hennigan
> > Sent: lunedì 25 agosto 2008 17.34
> > To: Cisco Mailing list
> > Subject: Re: [c-nsp] Surge protection on leased lines
> >
> > Brian Turnbow wrote:
> > > Hello,
> > >
> > > We have several customers that our having problems every time a storm
> > > goes through.
> > > Our national telco company seems to offer no lightning protection on
> > > their lines, and every storm causes a line outage and burns up the
> > > attached wic.
> > > We've made sure the chassis are grounded , but would also like to try
> > > and install a surge protection detween the v.35 interface of the telco
> > > and our CPEs.
> > > I see that Cisco offers a surge protection cable for smart serial
> > > interfaces, but not for classic serial interfaces.
> > > I wanted ask what others would recommend / experiences regarding surge
> > > protection on leased lines.
> >
> > This is an external CSU?
> >
> > I think you want it between the telco smartjack and the CSU, not on the
> > v.35.  This should be two pairs of wires.
> >
> > First thing to do is ensure that the telco smartjack, the CSU, and the
> > router are solidly connected to a common ground, as this may be the
> > source of the problem if the sneak current is not coming across the
> > leased line.
> >
> > There are a number of companies making lightning protectors for twisted
> > pair lines, Reliable Electric and Polyphaser are two.
> >
> > But, triple-check the grounding first because if it's
> common-mode across
> > a ground differential the protectors won't help.
> >
> > --
> > Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
> > Impulse Internet Service  -  http://www.impulse.net/
> > Your local telephone and internet company - 805 884-6323 - WB6RDV
> > _______________________________________________
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