In article ,
Johnny B Good wrote:
On Wed, 02 Sep 2015 14:39:26 +0100, Dave Liquorice wrote:

On Tue, 01 Sep 2015 22:08:45 GMT, Johnny B Good wrote:

It is my understanding that the neutral connection on the LV secondary
will be independently connected to a local earthing spike or spikes
provided by the utility company responsible for the supply. It may not
be as good a low earth resistance connection as that provided in urban
substations but it'll be a damn sight safer than relying on an 11 or 6
KV distribution neutral connection (assuming such a connection is
provided or even needed in the higher voltage levels of the
distribution network).

If you ever wander out in the the countryside and look at the 11 kV
power distribution it's all three wire, just the three phases. With a
single phase transformer one side will be connected to a real earth
connection at the pole, in our case it looks like a bit of 25 mm^2
before it disappears behind the protective capping and under ground.
This earth may or may not be carried on a seperate wire into the house,
around here the pole to house connection is mainly just two wire, phase
and neutral earth combined.

I'm now going to hit send and take a look at what the 'experts' have
said and see how big a fool I may have made of myself. :-)

The only glaring error is the use of LV to differentiate 240 from 11 kV.
To the DNO's 11 kV is "LV", I think 33 kV might be be lowest "HV"
but it could be 125 kV.

I had an idea that the "LV" upper limit was a little bit more inclusive
than the 240v house supply voltage level. I just wasn't too sure whether
"LV" included 33KV as well as 11KV.

I mentioned "LV" in the context of 240v to emphasise the fact that
despite its potential for electrocution, 240v wasn't considered to be a
high voltage by the Public Supply Utilities (PSUs).

Still, if that's the only 'glaring error' in my 'pre-google to confirm
the facts' posting, I don't think I made too big a fool of myself. :-)

BTW, the sight of only 3 wires on rural 11/33KV transmission lines was
also my recollection too but I've even seen 11/33KV lines strung with
just two wires on rare occasions which left me a little bit puzzled to
say the least.

Googling suggests these 2 wire lines might possibly be examples of a bi-
phase SWER transmission line (or, more likely here in the UK, just a
simple 2 wire single phase spur to a remote load not deemed worthy of the
expense of a 3 phase supply).

there are quite a few of the in what used to be NSHEB territory.

--
Please note new email address: