TN-S earth connection upgrade


J

John Rumm

As a general rule, do the electricity suppliers worry if one improves
the state of the earth connection to the cable sheath on a TN-S supply?

I was looking at someone's install the other day where all the earthing
and bonding in the house had obviously been brought up to standard at
some time in the relatively recent past, but the final connection from
the main earthing block to the cable head end was the original rather
feeble bit of bare steel stranded conductor that was probably no more
than 2mm^2 csa. It kind of made a nonsense of the nice new 16mm^2
running from the block to the CU etc.
 
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D

Dave Stanton

As a general rule, do the electricity suppliers worry if one improves
the state of the earth connection to the cable sheath on a TN-S supply?
Well I upgraded mine to 16mm^2 a while ago and no one complained.
There again I doubt meter readers would know or care. This was of course
pre Part P ;-)

Dave
 
A

Andrew Gabriel

As a general rule, do the electricity suppliers worry if one improves
the state of the earth connection to the cable sheath on a TN-S supply?

I was looking at someone's install the other day where all the earthing
and bonding in the house had obviously been brought up to standard at
some time in the relatively recent past, but the final connection from
the main earthing block to the cable head end was the original rather
feeble bit of bare steel stranded conductor that was probably no more
than 2mm^2 csa. It kind of made a nonsense of the nice new 16mm^2
running from the block to the CU etc.
On two I've done which required reconnecting the TN-S earth,
I left the original cable clamps in place. On one, an original
1955 installation, the earth clamp is a nice substantial brass
thing of much higher quality than todays clamps. On another,
the clamp screw seemed to have squashed into the lead sheath
very substantially, and I didn't fancy the incommer blowing up
on me, so I used the same clamp with a new earth cable connected.
 
S

Stephen Dawson

Andrew Gabriel said:
On two I've done which required reconnecting the TN-S earth,
I left the original cable clamps in place. On one, an original
1955 installation, the earth clamp is a nice substantial brass
thing of much higher quality than todays clamps. On another,
the clamp screw seemed to have squashed into the lead sheath
very substantially, and I didn't fancy the incommer blowing up
on me, so I used the same clamp with a new earth cable connected.
Strictly speaking the earth clamp on the cable is the property of the
distributor and should not be touched. Give you local electricity co's
emergency number a call and they can point you in the right direction to get
it replaced. The standard eath clamps from the shed should not be used as
they may squash the cable and cause an explosion!!

Regards

Steve Dawson
 
D

Dave Stanton

Strictly speaking the earth clamp on the cable is the property of the
distributor and should not be touched. Give you local electricity co's
emergency number a call and they can point you in the right direction to get
it replaced. The standard eath clamps from the shed should not be used as
they may squash the cable and cause an explosion!!

Regards

Steve Dawson
On rereading the OP I take it to mean the cable from the headend earth
connection to the CU. I don't think he means hes going to change the
actual sheath connection.

Dave
 
J

John Rumm

Dave said:
On rereading the OP I take it to mean the cable from the headend earth
connection to the CU. I don't think he means hes going to change the
actual sheath connection.
In this case I was not going to change anything since it is SEP! - just
more curious whey the original sparks who upgraded everything else (I
presume), had left that one last weak link...

There was no obvious clamp to the lead sheath - it almost looked like it
was soldered to it (although the connection was at the back of the cable
and under tape - so not immediately obvious).

The wire connected to the sheath was in turn connected to a modern 6 way
earth block, thence a couple of CUs and the main bonding to gas and
water pipes.
 
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R

Roger R

On two I've done which required reconnecting the TN-S earth,
I left the original cable clamps in place. On one, an original
1955 installation, the earth clamp is a nice substantial brass
thing of much higher quality than todays clamps. On another,
the clamp screw seemed to have squashed into the lead sheath
very substantially, and I didn't fancy the incommer blowing up
on me, so I used the same clamp with a new earth cable connected.
I found the clamp had changed the incoming cable shape from circular
to eliptical and the screw had made a similar significant indentation
in the flattish side. I too was quite worried about shorting out the
cable on refitting, so chose a different position away from the
damage.

This... from BBC4 TV programme 'Take one museum'
- Manchester Museum of Science and Industry.
Presenter (Paul Rose) described that to get the go ahead for building
the first electric power station in the uk, the proprietor had to
prove the distribution system was safe.

This was done by driving a cold chisel into a large energised
distribution cable - the power station proprietor was not the one
holding the chisel! Apparently all went well and the cable was
shorted out with no serious injury to those involved and the go ahead
was obtained. The section of cable and the chisel may be seen in
the museum.

Roger
 
S

Steve Firth

Roger R wrote:
[snip]
This... from BBC4 TV programme 'Take one museum'
- Manchester Museum of Science and Industry.
Presenter (Paul Rose) described that to get the go ahead for building
the first electric power station in the uk, the proprietor had to
prove the distribution system was safe.

This was done by driving a cold chisel into a large energised
distribution cable - the power station proprietor was not the one
holding the chisel! Apparently all went well and the cable was
shorted out with no serious injury to those involved and the go ahead
was obtained. The section of cable and the chisel may be seen in
the museum.
The first (public) electric power station in the UK was at Godalming in
Surrey, it was a hydroelectric generator and I'm bemused by the story
above since I can't see any direct link between Manchester and Godalming
in this respect. Nor can I understand why, if the tale is true, the
chisel is not located at Godalming museum.
 
C

Cicero

Steve Firth said:
Roger R wrote:
[snip]
This... from BBC4 TV programme 'Take one museum' - Manchester Museum of
Science and Industry.
Presenter (Paul Rose) described that to get the go ahead for building
the first electric power station in the uk, the proprietor had to
prove the distribution system was safe.

This was done by driving a cold chisel into a large energised
distribution cable - the power station proprietor was not the one
holding the chisel! Apparently all went well and the cable was
shorted out with no serious injury to those involved and the go ahead
was obtained. The section of cable and the chisel may be seen in
the museum.
The first (public) electric power station in the UK was at Godalming in
Surrey, it was a hydroelectric generator and I'm bemused by the story
above since I can't see any direct link between Manchester and Godalming
in this respect. Nor can I understand why, if the tale is true, the chisel
is not located at Godalming museum.
===============
The generating equipment was probably made in Manchester.

'Metro-Vick', 'Mather & Platt', 'Ferranti' (and many others) are all famous
manufacturers in the area. The demonstration cable and cold chisel mentioned
above were probably cut out after the demonstration and taken as a trophy to
the manufacturer's HQ.

Cic.
 
S

Steve Firth

Cicero said:
Steve Firth said:
Roger R wrote:
[snip]
This... from BBC4 TV programme 'Take one museum' - Manchester Museum of
Science and Industry.
Presenter (Paul Rose) described that to get the go ahead for building
the first electric power station in the uk, the proprietor had to
prove the distribution system was safe.

This was done by driving a cold chisel into a large energised
distribution cable - the power station proprietor was not the one
holding the chisel! Apparently all went well and the cable was
shorted out with no serious injury to those involved and the go ahead
was obtained. The section of cable and the chisel may be seen in
the museum.
The first (public) electric power station in the UK was at Godalming in
Surrey, it was a hydroelectric generator and I'm bemused by the story
above since I can't see any direct link between Manchester and Godalming
in this respect. Nor can I understand why, if the tale is true, the chisel
is not located at Godalming museum.
===============
The generating equipment was probably made in Manchester.

'Metro-Vick', 'Mather & Platt', 'Ferranti' (and many others) are all famous
manufacturers in the area. The demonstration cable and cold chisel mentioned
above were probably cut out after the demonstration and taken as a trophy to
the manufacturer's HQ.
Nice theory but rather at odds with the facts. The Godalming generation
scheme was commissioned by Calder & Barrett in 1881 and the alternator
was provided by Siemens AG.
 
C

Cicero

Steve Firth said:
Cicero said:
Steve Firth said:
Roger R wrote:
[snip]
This... from BBC4 TV programme 'Take one museum' - Manchester Museum
of Science and Industry.
Presenter (Paul Rose) described that to get the go ahead for building
the first electric power station in the uk, the proprietor had to
prove the distribution system was safe.

This was done by driving a cold chisel into a large energised
distribution cable - the power station proprietor was not the one
holding the chisel! Apparently all went well and the cable was
shorted out with no serious injury to those involved and the go ahead
was obtained. The section of cable and the chisel may be seen in
the museum.
The first (public) electric power station in the UK was at Godalming in
Surrey, it was a hydroelectric generator and I'm bemused by the story
above since I can't see any direct link between Manchester and Godalming
in this respect. Nor can I understand why, if the tale is true, the
chisel is not located at Godalming museum.
===============
The generating equipment was probably made in Manchester.

'Metro-Vick', 'Mather & Platt', 'Ferranti' (and many others) are all
famous manufacturers in the area. The demonstration cable and cold chisel
mentioned above were probably cut out after the demonstration and taken
as a trophy to the manufacturer's HQ.
Nice theory but rather at odds with the facts. The Godalming generation
scheme was commissioned by Calder & Barrett in 1881 and the alternator was
provided by Siemens AG.
==================
In that case it would appear that the Godalming museum was a bit slow off
the mark in collecting exhibits. As far as I know the Manchester museum is
sometimes referred to as a 'national' museum of industry which might put it
ahead in the pecking order for exhibits or maybe it was established earlier
than the one at Godalming.

Cic.
 
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D

Dave Stanton

The wire connected to the sheath was in turn connected to a modern 6 way
earth block, thence a couple of CUs and the main bonding to gas and
water pipes.
I was lucky, mine had a proper 2 x screw terminal.

Dave
 
R

Roger R

Roger R wrote:
[snip]
This... from BBC4 TV programme 'Take one museum'
- Manchester Museum of Science and Industry.
Presenter (Paul Rose) described that to get the go ahead for building
the first electric power station in the uk, the proprietor had to
prove the distribution system was safe.

This was done by driving a cold chisel into a large energised
distribution cable - the power station proprietor was not the one
holding the chisel! Apparently all went well and the cable was
shorted out with no serious injury to those involved and the go ahead
was obtained. The section of cable and the chisel may be seen in
the museum.
The first (public) electric power station in the UK was at Godalming in
Surrey, it was a hydroelectric generator and I'm bemused by the story
above since I can't see any direct link between Manchester and Godalming
in this respect. Nor can I understand why, if the tale is true, the
chisel is not located at Godalming museum.
The tale was as I recollected it from the programme broadcast only a
couple of weeks ago on Tuesday 28 February 2006, 8.30pm, BBC Four.

You can hear the audio that accompanied the programme by scrolling
down to the Manchester museum on this page:
http://www.bbc.co.uk/sn/tvradio/programmes/take_one/programme.shtml

As to the accuracy of 'the first electric power station', that might
depend on the type and nature of the prime mover and generator and
who, how, or what it supplied, etc, etc.

Havn't had a chance to hear the programme again yet and get the detail
- if specified.

Roger
 
R

Roger R

Havn't had a chance to hear the programme again yet and get the detail
- if specified.
Listened to the audio last night. (section 4 of the unzipped audio)
The presenter says that around 1880 electrical power generation was
limited to individual private systems powering their own equipment.
(Direct current systems?)

Mr Ferranti's idea was a central generating station providing a
public supply of alternating current over a distribution network to
consumers. This was to be the first public A/C supply and there were
concerns about the safety of the distribution.

To answer these concerns Mr Ferranti had developed a line circuit
breaker that he claimed would protect the public, the line and the
generating equipment in the event of a short on a cable.

A public demonstration was arranged as was the norm for placating
public concerns about new technology. The chisel was driven into a
cable energised with 10,000 volts A/C. The presenter does not say
where the demo took place.

The Manchester connection is that Mr Ferranti was a mancunian, and I
would think his factory was in Manchester, which is probably why the
museum has the artifacts.

Roger
 
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C

Cicero

Roger R said:
Listened to the audio last night. (section 4 of the unzipped audio)
The presenter says that around 1880 electrical power generation was
limited to individual private systems powering their own equipment.
(Direct current systems?)

Mr Ferranti's idea was a central generating station providing a
public supply of alternating current over a distribution network to
consumers. This was to be the first public A/C supply and there were
concerns about the safety of the distribution.

To answer these concerns Mr Ferranti had developed a line circuit
breaker that he claimed would protect the public, the line and the
generating equipment in the event of a short on a cable.

A public demonstration was arranged as was the norm for placating
public concerns about new technology. The chisel was driven into a
cable energised with 10,000 volts A/C. The presenter does not say
where the demo took place.

The Manchester connection is that Mr Ferranti was a mancunian, and I
would think his factory was in Manchester, which is probably why the
museum has the artifacts.

Roger
================
To confirm what you say.

The museum exhibit is actually named, "Ferranti's chisel" and the presenter
(Rose) actually states this in the programme.

Ferranti is located in Oldham which is now I believe part of Greater
Manchester.

The actual demonstration probably took place at Deptford power station - see
here: http://www.swehs.co.uk/docs/news25su.html

Cic.
 

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