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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

Cable broadband anti-surge protection



 
 
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  #1  
Old July 5th 05, 10:45 PM posted to uk.telecom.broadband
McSpreader
external usenet poster
 
Posts: 52
Default Cable broadband anti-surge protection

What is needed to provide protection from surges on the line when you
are using cable broadband? Any recommendations for products to choose
from?
  #2  
Old July 6th 05, 03:09 PM posted to uk.telecom.broadband
w_tom
external usenet poster
 
Posts: 19
Default Cable broadband anti-surge protection

McSpreader wrote:
What is needed to provide protection from
surges on the line when you are using
cable broadband? Any recommendations
for products to choose from?


Earth ground provides the protection. Any wire (not just phone wire)
that enters the building must connect to a single point ground - either
by a direct hardwire connection or through a surge protector.

Others are easily deceived by inferior protectors manufacturers into
believing the protector is protection. The protector and protection
are two different component of a surge protection system. All
protection systems require protection: single point earth ground. Some
systems also use surge protectors to make that essential 'less than 3
meter' connection to earth.

Surges can enter on any utility wire. Electronics are damaged when a
transient finds a path to earth ground via electronics. Electronics
already contain effective protection. But a transient not earthed at
the service entrance can overwhelm protection already inside appliances
- including that modem.

One common source of damaged modems is a surge incoming on AC
electric, through the modem, then outgoing to earth ground via the
telephone line protector. First electricity flows through everything
in that path. Then something in that path fails. Or incoming on a
phone line, destructively through modem, then outgoing via AC electric.
Notice one prerequisite. To be damaged, the electronics must have
both an incoming and outgoing path. After all, surges are electricity.
Electricity that seeks earth ground destructively.

This example demonstrates two points. First, every wire of every
utility must be earthed before it can enter the building. This is
called a 'whole house' protector for AC electric and phone. Or ground
block connects coax cable directly to earth ground - no protector
required.

Second, if utilities enter at different locations and therefore use
different earth grounds, then those different grounds can still create
surge damage. This figure from the NIST is used to demonstrate a fax
machine damaged due to multiple and separated earth grounds:
http://www.epri-peac.com/tutor*ials/sol01tut.html

Bottom line is this: single point earth ground is protection.
Plug-in protectors don't provide this most essential component. How to
identify a protector that is not effective? 1) No dedicated wire for a
less than 3 meter connection to earth ground. 2) Manufacturer avoids
all discussion about earthing.

A protector is only as effective as its earth ground. No short
connection to earth ground means no effective protection. A protector
is only as effective as its earth ground. Effective proetction earths
destructive transients before they can enter the building. Earth
ground is the only component of a surge protection system that is
absolutely essential. All connections to earth ground (via hardwire or
surge protector) best make a 'less than 3 meter' connection to the same
earth ground.

  #4  
Old July 6th 05, 06:50 PM posted to uk.telecom.broadband
Peter
external usenet poster
 
Posts: 116
Default Cable broadband anti-surge protection

On 6 Jul 2005 06:09:05 -0700, "w_tom" wrote:

McSpreader wrote:
What is needed to provide protection from
surges on the line when you are using
cable broadband? Any recommendations
for products to choose from?


Earth ground provides the protection. Any wire (not just phone wire)
that enters the building must connect to a single point ground - either
by a direct hardwire connection or through a surge protector.


Not in the UK - please be aware that people you reply to may not live
in the US and therefore different regulations will apply.


  #5  
Old July 6th 05, 07:30 PM posted to uk.telecom.broadband
w_tom
external usenet poster
 
Posts: 19
Default Cable broadband anti-surge protection

Posted is earthing that applies throughout the world. Some countries
with better codes even require this earthing. Others with less safe
electrical systems do not require it. But earthing for lightning
enhances what is required by human safety earthing.

They are not selling products that contradict local codes. Products
for N American protection may not meet the same safety codes in other
nations. Lightning protection earthing systems, sold in every country,
would meet those local requirements. Still, the concept of single
point earthing - an enhancement of the earthing system as required in
most western nations - has been routinely installed even long before
WWII to eliminate lightning damage. Concepts of protection are that
well proven and installed that routinely in buildings where no
electronics damage is acceptable.

An example of how earthing for lightning protection exceeds local code
requirements. Some codes may permit multiple earthing. But for
lightning protection, that earthing must be single point meaning all
utilities must enter the building at a common serive entrance.

Bottom line: purchase every surge protector sold in the country. But
if the building does not have a single point earth ground, then all
those surge protectors are ineffective. Earthing - and not surge
protectors - define transistor protection. Earthing is also installed
where human life would be endangered by AC electricity. Nations with
superior safety codes specifically require earthing - for human safety.
For lightning protection, code requirements sometimes are exceeded.
The earthing system, installed for human safety, may be enhanced for
transistor safety. And yet there is no way around that fact. Earthing
defined transient protection.

Any wire that can be directly earthed requires no surge protector.
For example, not every incoming AC wire can be earthed. Therefore the
earthing is provided by a 'whole house' protector. Utility makes a
connection to earth only during the potentially destructive transient.


A surge protector is only as effective as its earth ground.
Ineffective (and grossly overpriced) protectors simply enhance their
profits by avoiding any mention of THE most critical component in any
earthing system - single point earth ground.

"David G. Bell" wrote:
I've no argument with the basic thesis of the article, but anyone
reading this should remember that the regulations on electrical
installations may differ significantly. I am not an electrician, nor do
I play one on TV, but I am let to understand that ground-earths are
currently frowned on in the UK.


  #6  
Old July 6th 05, 11:11 PM posted to uk.telecom.broadband
McSpreader
external usenet poster
 
Posts: 52
Default Cable broadband anti-surge protection

"w_tom" wrote in news:1120655345.241731.244290
@g49g2000cwa.googlegroups.com:

First, every wire of every
utility must be earthed before it can enter the building.


And that means short-circuiting everything. Are you sure you
understand this electrickery stuff?
  #7  
Old July 7th 05, 01:00 AM posted to uk.telecom.broadband
w_tom
external usenet poster
 
Posts: 41
Default Cable broadband anti-surge protection

Apparently the concept of earthing was not understood.
Since this pre-WWII concept is new, the technical explanation
requires reading multiple times. Anything technically good
and new (such as IEEE papers) required multiple readings.

Previously posted was:
Any wire that can be directly earthed requires no surge
protector. For example, not every incoming AC wire can be
earthed. Therefore the earthing is provided by a 'whole
house' protector.


That obviously means that earthing need not short circuit
every thing. Go back and read that post again. This is
technology so well proven that virtually every telephone
switching station uses it. Commercial radio stations do
this. Earthing of the antenna and other equipment essential
so that the station stays on the air and does not suffer
damage from direct lightning strikes. How do they do that if
the antenna is earthed? Again reread that above paragraph.

McSpreader wrote:
"w_tom" wrote in news:1120655345.241731.244290
@g49g2000cwa.googlegroups.com:
First, every wire of every utility must be earthed before
it can enter the building.


And that means short-circuiting everything. Are you sure
you understand this electrickery stuff?

  #8  
Old July 7th 05, 03:09 AM posted to uk.telecom.broadband
David G. Bell
external usenet poster
 
Posts: 121
Default Cable broadband anti-surge protection

On Wednesday, in article
"w_tom" wrote:

Apparently the concept of earthing was not understood.
Since this pre-WWII concept is new, the technical explanation
requires reading multiple times. Anything technically good
and new (such as IEEE papers) required multiple readings.

Previously posted was:
Any wire that can be directly earthed requires no surge
protector. For example, not every incoming AC wire can be
earthed. Therefore the earthing is provided by a 'whole
house' protector.


That obviously means that earthing need not short circuit
every thing. Go back and read that post again. This is
technology so well proven that virtually every telephone
switching station uses it. Commercial radio stations do
this. Earthing of the antenna and other equipment essential
so that the station stays on the air and does not suffer
damage from direct lightning strikes. How do they do that if
the antenna is earthed? Again reread that above paragraph.

McSpreader wrote:
"w_tom" wrote in news:1120655345.241731.244290
@g49g2000cwa.googlegroups.com:
First, every wire of every utility must be earthed before
it can enter the building.


And that means short-circuiting everything. Are you sure
you understand this electrickery stuff?


As I've said, I'm not an electrician.

I wouldn't be surprised if American jargon was different from British
jargon.

I suspect there's some critical component being missed from the
description, some sort of voltage-dependent resistance at its simplest,
which shorts each wire of every utility to earth when a lighting-induced
surge hits.

It's possible he means something different by "earthed".

There's no way that you can directly connect both live and neutral to an
earth. You can't do it with both conductors of an aerial feed, because
the aerial wouldn't work. And on a transmitter the SWR could get high
enough to blow the power stage of the RF amplifier.







--
David G. Bell -- SF Fan, Filker, and Punslinger.

"I am Number Two," said Penfold. "You are Number Six."
  #9  
Old July 7th 05, 06:16 AM posted to uk.telecom.broadband
w_tom
external usenet poster
 
Posts: 41
Default Cable broadband anti-surge protection

Earthing an antenna or AC power via a surge protector, in
normal operation, means the surge protector is open circuit.
In normal operation, the protector acts as if it does not even
exist. When a destructive transient occurs, the protector
shunts to earth. This 'shunt' is not destructive and conducts
electricity only during the transient. Once a transient
terminates, then the protector returns to its 'open circuit'
state (assuming the protector was properly sized so as to not
fail catastrophically). It was assumed that the reader
understood what is meant by 'earthing a wire via the
protector'.

When I said the AC electric wire is earthed through a
protector, that does not mean the AC electric wire is always
conducting electricity to earth. Why? Protectors are open
circuit during normal voltage operation and shunt (short
circuit, close like a switch, etc) during excessive voltages.

If one did not understand what a shunt mode protector does,
then this below quote might lead one to assume that AC
electric wire was always shorted to and conducting electricity
into earth:
every wire of every utility must be earthed before it can enter
the building. This is called a 'whole house' protector for AC
electric and phone.

A utility wire earthed via a surge protector only conducts
electricity into earth when voltage is excessive. This
voltage dependency characterizes shunt mode surge protectors.

If one assumes a plug-in protector blocks, stops, or absorbs
transients from wall receptacle into appliance, then one has
been deceived as to what surge protectors actually do. Then
that person would not comprehend what is meant by 'earthing
the AC electric wire through a protector'. A surge protector
conducts nothing - no current - until that rare time when
voltage is excessive. During that excessive voltage, the
protector acts like a switch; shunts (shorts) all wires
together. Shorting action has diminished effectiveness if
protector is not shunting wires 'less than 3 meters' to earth
ground.

If one properly understands the function of shunt mode
protectors (ie 'whole house' protector), then earthing the
incoming utility line does not mean that utility line is
always conducting electricity to earth. Sentence assumes the
reader comprehends what a protector does.

"David G. Bell" wrote:
As I've said, I'm not an electrician.

I wouldn't be surprised if American jargon was different from British
jargon.

I suspect there's some critical component being missed from the
description, some sort of voltage-dependent resistance at its
simplest, which shorts each wire of every utility to earth when
a lighting-induced surge hits.

It's possible he means something different by "earthed".

There's no way that you can directly connect both live and neutral to an
earth. You can't do it with both conductors of an aerial feed, because
the aerial wouldn't work. And on a transmitter the SWR could get high
enough to blow the power stage of the RF amplifier.

  #10  
Old July 7th 05, 10:22 AM posted to uk.telecom.broadband
McSpreader
external usenet poster
 
Posts: 52
Default Cable broadband anti-surge protection

McSpreader wrote in
:

What is needed to provide protection from surges on the line
when you are using cable broadband? Any recommendations for
products to choose from?


Leaving aside the rambling theoretical discussion disappearing down a
rathole, can we get back to the topic, please?

For the avoidance of doubt:
- assume that the choice of where and how utility feeds (phone,
cable, power) enter a house are not open to choice by the
householder.
- similarly, earthing practices are dictated by IEE (not IEEE)
regulations, and are not open to personal preferences.
- is there even a significant risk, given the cable feed is
underground and short - to the nearest 'junction' box where it
becomes fibre.
 




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