Here's a pic of a friend's consumer unit:

http://i54.tinypic.com/r8wne1.jpg

As you can see there is an underground cable coming in to the house.
From my limited knowledge of such things, I would say it's a paper-lead
cable.

There is no Earth connection to the cable. The green wire (at the top of
the pic) is an earth wire going from the earth bar in the Consumer Unit
to a rod outside.

This makes the installation TT, probably because other houses in the
street have overhead connections.

Now, there was a thread a while back where I'm reasonably sure somebody
was talking about getting a TT supply converted to TN-C-S (PME).

What do you think the chances are of getting the DNO to convert this TT
arrangement to TN-C-S and, at the end of the day, is there any real
advantage?

Or did I misunderstand and somebody was saying that the DNO was
pro-actively converting TT supplies to PME and if only happens to you if
they're doing down your street.

Cheers,
DaveyOz

"Dave Osborne" wrote in message
...
Here's a pic of a friend's consumer unit:

http://i54.tinypic.com/r8wne1.jpg

As you can see there is an underground cable coming in to the house.
From my limited knowledge of such things, I would say it's a
paper-lead
cable.

There is no Earth connection to the cable. The green wire (at the
top of
the pic) is an earth wire going from the earth bar in the Consumer
Unit
to a rod outside.

This makes the installation TT, probably because other houses in the
street have overhead connections.

Now, there was a thread a while back where I'm reasonably sure
somebody
was talking about getting a TT supply converted to TN-C-S (PME).

What do you think the chances are of getting the DNO to convert this
TT
arrangement to TN-C-S and, at the end of the day, is there any real
advantage?

Or did I misunderstand and somebody was saying that the DNO was
pro-actively converting TT supplies to PME and if only happens to
you if
they're doing down your street.

Cheers,
DaveyOz

When EDF put 3 phase into my barn, as it was overhead I had assumed it
would be TT, however they insisted on it being PME (I had to
re-arrange my earthing) as the feed transformer is very close.

AWEM

"Dave Osborne" wrote in message
...
Here's a pic of a friend's consumer unit:

http://i54.tinypic.com/r8wne1.jpg

As you can see there is an underground cable coming in to the house. From
my limited knowledge of such things, I would say it's a paper-lead cable.

There is no Earth connection to the cable. The green wire (at the top of
the pic) is an earth wire going from the earth bar in the Consumer Unit to
a rod outside.

This makes the installation TT, probably because other houses in the
street have overhead connections.

Now, there was a thread a while back where I'm reasonably sure somebody
was talking about getting a TT supply converted to TN-C-S (PME).

What do you think the chances are of getting the DNO to convert this TT
arrangement to TN-C-S and, at the end of the day, is there any real
advantage?

Or did I misunderstand and somebody was saying that the DNO was
pro-actively converting TT supplies to PME and if only happens to you if
they're doing down your street.

Cheers,
DaveyOz

Whether it can be converted to PME depends on the local network. It is
impossible to tell from the photo. Overhead wires do not stop it being PME
capable - our network is PME here but most houses are supplied overhead.
You can ask your DNO. but they are unlikely to convert it to PME for free
nowadays unless they they have to replace the service head for another
reason. It is not smelling/smoking is it?! Is PME an advantage?
Debatable, but the consensus is yes. You get the additional protection of
mcbs operating for (some) faults to earth, but incur the small risk of a
lost neutral. That risk is greater with overhead wires as the final
connection to your property. If you already have a perfectly good TT
system, then I suggest you test the rcds regularly but leave well alone.
Regards
Bruce

BruceB wrote:


"Dave Osborne" wrote in message
...
Here's a pic of a friend's consumer unit:

http://i54.tinypic.com/r8wne1.jpg

As you can see there is an underground cable coming in to the house.
From my limited knowledge of such things, I would say it's a
paper-lead cable.

There is no Earth connection to the cable. The green wire (at the top
of the pic) is an earth wire going from the earth bar in the Consumer
Unit to a rod outside.

This makes the installation TT, probably because other houses in the
street have overhead connections.

Now, there was a thread a while back where I'm reasonably sure
somebody was talking about getting a TT supply converted to TN-C-S (PME).

What do you think the chances are of getting the DNO to convert this
TT arrangement to TN-C-S and, at the end of the day, is there any real
advantage?

Or did I misunderstand and somebody was saying that the DNO was
pro-actively converting TT supplies to PME and if only happens to you
if they're doing down your street.

Cheers,
DaveyOz

Whether it can be converted to PME depends on the local network. It is
impossible to tell from the photo. Overhead wires do not stop it being
PME capable - our network is PME here but most houses are supplied
overhead. You can ask your DNO. but they are unlikely to convert it to
PME for free nowadays unless they they have to replace the service head
for another reason. It is not smelling/smoking is it?! Is PME an
advantage? Debatable, but the consensus is yes. You get the additional
protection of mcbs operating for (some) faults to earth, but incur the
small risk of a lost neutral. That risk is greater with overhead wires
as the final connection to your property. If you already have a
perfectly good TT system, then I suggest you test the rcds regularly but
leave well alone.
Regards
Bruce

Thanks for that Bruce. I found this document this morning:

http://www.spenergynetworks.co.uk/Ne...g%20Policy.pdf

(i.e. http://preview.tinyurl.com/39bxbvw ) which gave me the info I
needed. Leave well alone is indeed the plan. There's already RCD provision.