In message , John
Rumm writes
On 04/07/2017 11:17, Graeme wrote:

http://www.binnsroad.co.uk/misc/leccy/index.html

(I think your description probably wants a "(far left)" where it
currently has a "(far right)" ;-)

Bugger. Fixed :-)

I have added a few photos of the house end. Not the best photos, so
will try for some better ones, and the TN business, probably tomorrow.

--
Graeme

On 04/07/2017 12:59, John Rumm wrote:
On 04/07/2017 11:17, Graeme wrote:
In message , John
Rumm writes
On 01/07/2017 07:37, Graeme wrote:

This, I confess, is where I get lost. Several times, over a good few
years, I have re

ad the Wiki article and looked at the incoming supply,
but am still none the wiser. I'll need to take good photos of both CUs
and post them here, in the hope that someone will be able to see
exactly
which system is in use.

Yup photos would be good. Especially if they are of installs that are
different in look from the ones we already have - then we can pinch em
to update the article with ;-)

Right. Photos here :

http://www.binnsroad.co.uk/misc/leccy/index.html

Oh, nice job. ta.

(I think your description probably wants a "(far left)" where it
currently has a "(far right)" ;-)

That looks like its TN, now the next question is TN-S or TN-C-S - hard
to tell from just the picture. If you were to take out those two screws
on the rectangular faceplate just under the main fuse, and have a peek
in there, that would probably tell you.

For example:

http://wiki.diyfaq.org.uk/index.php/...PMECutout3.jpg

Shows what could be a TN-C-S cutout, but the link between the neutral
and earth blocks on the right is missing, and a discrete earth
connection from the armour of the split concentric cable is connected to
the bottom of the earthing block on the far right.

Compare with:

http://wiki.diyfaq.org.uk/index.php/...ePMECutout.jpg

That has the link in place to join the earth terminal to the incoming
neutral at the cutout.

I would guess yours will be like the former (i.e. TN-S)

Adam may be able to spot more from the photos.


Afraid not. It's deffo a TN supply.

But does it matter if it TN-S or a TN-C-S? If you treat it as a TN-C-S
then you have covered the TN-S rules.


So it seems the shop CU is the one providing the water bonding not the
house CU. Therefore this would require a 10mm earth from the house CU to
the earth bar next to the shop CU.

--
Adam

In message , ARW
writes

So it seems the shop CU is the one providing the water bonding not the
house CU. Therefore this would require a 10mm earth from the house CU
to the earth bar next to the shop CU.

What I don't understand is what was the position prior to the shop
installation? The shop was not built until 1979, but the house (1880s)
must have had electricity before then.

The shop and house, although having independent electricity supplies,
share a common water supply. What I need to check, I think, is whether
there is a water bonding point in the house.
--
Graeme

On 04/07/2017 19:51, Graeme wrote:
In message , ARW
writes

So it seems the shop CU is the one providing the water bonding not the
house CU. Therefore this would require a 10mm earth from the house CU
to the earth bar next to the shop CU.

What I don't understand is what was the position prior to the shop
installation? The shop was not built until 1979, but the house (1880s)
must have had electricity before then.

The shop and house, although having independent electricity supplies,
share a common water supply. What I need to check, I think, is whether
there is a water bonding point in the house.


It's not always easy. You are supposed to bond where the pipe enters the
building.

So if the shop supply is removed you need to bond from the house CU to
the earth bar at the shop.

--
Adam

In message , ARW
writes
On 04/07/2017 19:51, Graeme wrote:

What I don't understand is what was the position prior to the shop
installation? The shop was not built until 1979, but the house (1880s)
must have had electricity before then.

It's not always easy. You are supposed to bond where the pipe enters
the building.

Thanks Adam. The water supply enters the house from the water mains,
the water supply in the shop, where the earth is bonded, is merely a
branch off the house supply. I'll need to investigate further. One
thing I am sure of is that there is no plastic piping, apart from
overflows.
--
Graeme

On 04/07/2017 19:42, ARW wrote:
On 04/07/2017 12:59, John Rumm wrote:
On 04/07/2017 11:17, Graeme wrote:
In message , John
Rumm writes
On 01/07/2017 07:37, Graeme wrote:

This, I confess, is where I get lost. Several times, over a good few
years, I have re

ad the Wiki article and looked at the incoming supply,
but am still none the wiser. I'll need to take good photos of both
CUs
and post them here, in the hope that someone will be able to see
exactly
which system is in use.

Yup photos would be good. Especially if they are of installs that are
different in look from the ones we already have - then we can pinch em
to update the article with ;-)

Right. Photos here :

http://www.binnsroad.co.uk/misc/leccy/index.html

Oh, nice job. ta.

(I think your description probably wants a "(far left)" where it
currently has a "(far right)" ;-)

That looks like its TN, now the next question is TN-S or TN-C-S - hard
to tell from just the picture. If you were to take out those two screws
on the rectangular faceplate just under the main fuse, and have a peek
in there, that would probably tell you.

For example:

http://wiki.diyfaq.org.uk/index.php/...PMECutout3.jpg

Shows what could be a TN-C-S cutout, but the link between the neutral
and earth blocks on the right is missing, and a discrete earth
connection from the armour of the split concentric cable is connected to
the bottom of the earthing block on the far right.

Compare with:

http://wiki.diyfaq.org.uk/index.php/...ePMECutout.jpg

That has the link in place to join the earth terminal to the incoming
neutral at the cutout.

I would guess yours will be like the former (i.e. TN-S)

Adam may be able to spot more from the photos.


Afraid not. It's deffo a TN supply.

But does it matter if it TN-S or a TN-C-S? If you treat it as a TN-C-S
then you have covered the TN-S rules.

Yup, fair point...

So it seems the shop CU is the one providing the water bonding not the
house CU. Therefore this would require a 10mm earth from the house CU to
the earth bar next to the shop CU.

Looking at the extra photo's of the house end now, it looks like the
cutout has two cables on the supply side - the second one likely to be
the feed that goes to the shop.

With that cutout it looks like they have split out the conductors of the
supply cable outside of the enclosure, and I can't see (although the
photo is not that clear) a separate earth connection from the supply
cable into the cutout, but I can see several earth connections to its
neutral block. So I am leaning toward TN-C-S on that end - which would
strongly suggest the same at the other end.

So yup, work out the total load on the shop end, apply some diversity,
look at the length of cable and select a suitable sub main size - you
may only need 6 or 10mm^2 since some of the shop end circuits are no
longer loaded by the sounds of it. Slap in an additional 10mm^2 single
bonding connection as well, and you should be mostly sorted. Ideally the
main bond to the water pipe should then be from the point of pipe entry,
and to the main earth terminal in the house end. (although if its to the
shop end and connected to the shop CU, that's going to be nearly as good
so long as you have adequate bonding between the CUs)



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 05/07/2017 12:08, John Rumm wrote:


Looking at the extra photo's of the house end now, it looks like the
cutout has two cables on the supply side - the second one likely to be
the feed that goes to the shop.

With that cutout it looks like they have split out the conductors of the
supply cable outside of the enclosure, and I can't see (although the
photo is not that clear) a separate earth connection from the supply
cable into the cutout, but I can see several earth connections to its
neutral block. So I am leaning toward TN-C-S on that end - which would
strongly suggest the same at the other end.


Agreed

So yup, work out the total load on the shop end, apply some diversity,
look at the length of cable and select a suitable sub main size - you
may only need 6 or 10mm^2 since some of the shop end circuits are no
longer loaded by the sounds of it. Slap in an additional 10mm^2 single
bonding connection as well, and you should be mostly sorted. Ideally the
main bond to the water pipe should then be from the point of pipe entry,
and to the main earth terminal in the house end. (although if its to the
shop end and connected to the shop CU, that's going to be nearly as good
so long as you have adequate bonding between the CUs)

Again I agree - with one small suggestion - if you take the 10mm to the
earth bar next to the shop CU (say it's a lot of effort to replace the
earth all the way to the stop tap) and change it's name from "earth bar"
to "earth marshalling terminal" I would say you have fulfilled the regs:-)


--
Adam

In message , ARW
writes

Again I agree - with one small suggestion - if you take the 10mm to the
earth bar next to the shop CU (say it's a lot of effort to replace the
earth all the way to the stop tap) and change it's name from "earth
bar" to "earth marshalling terminal" I would say you have fulfilled the
regs:-)

Thank you all, particularly John and Adam. I'm not ignoring the advice,
but am not in a position to proceed further yet, although the issue is
still live (ha ha).

One factor is change of supplier to the house, which has resulted in an
increased fixed daily charge, which makes amalgamating the two supplies
less attractive economically. What I do intend to do is take better
pictures of the earth of both supplies, just to establish the earthing
types.

Cheers,
--
Graeme

On 08/08/2017 09:52, Graeme wrote:

One factor is change of supplier to the house, which has resulted in an
increased fixed daily charge, which makes amalgamating the two supplies
less attractive economically.


Is this true? Combining two supplies means you lose one of the higher
cost daily fixed charges.



--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

In message , alan_m
writes
On 08/08/2017 09:52, Graeme wrote:

One factor is change of supplier to the house, which has resulted in
an increased fixed daily charge, which makes amalgamating the two
supplies less attractive economically.


Is this true? Combining two supplies means you lose one of the higher
cost daily fixed charges.

Indeed, but the question remains, having paid for the conversion to one
supply, how long does it take to recoup that amount? Yet to be
determined. It was £95 a year at my old rates, but new (higher) rates
from next month.
--
Graeme

On 08/08/2017 09:52, Graeme wrote:
In message , ARW
writes

Again I agree - with one small suggestion - if you take the 10mm to
the earth bar next to the shop CU (say it's a lot of effort to replace
the earth all the way to the stop tap) and change it's name from
"earth bar" to "earth marshalling terminal" I would say you have
fulfilled the regs:-)

Thank you all, particularly John and Adam. I'm not ignoring the advice,
but am not in a position to proceed further yet, although the issue is
still live (ha ha).

One factor is change of supplier to the house, which has resulted in an
increased fixed daily charge, which makes amalgamating the two supplies
less attractive economically. What I do intend to do is take better
pictures of the earth of both supplies, just to establish the earthing
types.

Cheers,


When you are ready post the photos.

--
Adam