DIYbanter - View Single Post

Andrew Gabriel

In article ,
writes:
In alt.engineering.electrical Arfa Daily wrote:
|
| "jakdedert" wrote in message
| . ..
| I'm a little confused about a 230 volt circuit. In what part of the world
| does the utility supply 230v?
|
| jak
|
| In theory, it's 230 on a single phase - neutral circuit here in the UK now,
| but in practice, it's actually nearer the previously accepted 240v for the
| most part ...

Is the grounded conductor in a 2-wire 230/240 volt system fed to each home
referred to as "neutral" even in UK?

Yes, although we have 3 types of supply arrangement for earthing
used on public supplies. (Note that on 240V, there's often far
more distance between the consumer and the transformer than
you'll find in the US on 120V supplies.)

TN-S:
Neutral is grounded only at the transformer, but a separate
earth conductor is carried in the supply network and brought
into the home from that same grounding point.

TN-C-S (also known as Protective Multiple Earthing):
A single PEN (Protective Earth and Neutral) conductor from
the transformer serves as both neutral and ground connection
in the supply network. The PEN conductor must also be earthed
regularly throughout the supply network, and it requires very
high integrity connections to ensure the risk of it breaking
is very low (this is a legal requirement). Once the supply
reaches the consumer, the PEN conductor is split into separate
neutral and earth conductors in the installation.

TT:
The supplier grounds the neutral as for TN-S, but doesn't
provide the consumer with any earthing connection. The
consumer needs to make their own ground connection for earthing
(and shouldn't cross-connect this to the neutral).
TT is only found on old rural overhead supply networks, and
they are upgraded to TN-C-S when due for refurbishment.

Even if the supplier does provide an earth connection (TN-S
or TN-C-S), the installation can choose to ignore it and be
wired as a TT system. This is sometimes done for submains
to outbuildings and outdoor electrics, even when the main
installation is TN-S or TN-C-S.

These earthing system arrangements are covered in the uk.d-i-y
FAQ: http://www.diyfaq.org.uk/electrical/...al.html#system

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]