Heard a sort of chattering sound from the MCB (30A) supplying one of the
ring mains in our house this afternoon. Turn of the MCB, turn it back on
again, all is ok for a little while (maybe 10 minutes?) then it starts
again.

The circuit in question is one of four ring mains in the house, it
supplies the sitting room, one bedroom , a socket in the hall, in the
conservatory and the dressing room. generally lightly loaded - a few
table/standard lamps, TV, VCR, DVD etc.

Whilst investigating this problem I noticed that when this circuit was
switched on the disc on the meter started fair whizzing round - 30
rev/minute up from the say about 3 rev/minute is was doing normally.

My quick calcs indicate that 30 rev/min implies something like 10kW/h
being consumed - around 40A? , or have I made some big boo-boo?

Anyway, there is nothing on the circuit drawing anything like that (no
we don't have any secret electric showers, or unknown immersion heaters
etc.) These symptoms continue to occur once everything on the circuit
has been disconnected.

I've not had time today to investigate this more thoroughly, the circuit
is isolated now via the MCB pending time tomorrow.

So, my thought so far is that there is some fault in the fixed wiring,
causing a high current draw, and that the MCB is faulty in some way,
hence the noise rather than tripping.

Does the above sound a reasonable diagnosis?

I can check out the MCB by swopping it with others in the CU I guess, if
it is faulty then I'm not sure if replacing it is going to be a problem
or not.

The CU is a pretty old Crabtree one, you can see a couple of piccies
he

http://galoka.adsl24.co.uk/temp/IMG_0085.jpg
http://galoka.adsl24.co.uk/temp/IMG_0088.jpg

Does anyone know if I will be able to find something to fit?

Thanks
--
Chris French

"chris French" wrote in message
...
....
I can check out the MCB by swopping it with others in the CU I guess, if
it is faulty then I'm not sure if replacing it is going to be a problem or
not.

The CU is a pretty old Crabtree one, you can see a couple of piccies he

http://galoka.adsl24.co.uk/temp/IMG_0085.jpg
http://galoka.adsl24.co.uk/temp/IMG_0088.jpg

Does anyone know if I will be able to find something to fit?

They look the same type as used in a couple of my factory distribution
boards and they haven't been available for the past ten years.

Colin Bignell

In article ,
chris French writes:

Heard a sort of chattering sound from the MCB (30A) supplying one of the
ring mains in our house this afternoon. Turn of the MCB, turn it back on
again, all is ok for a little while (maybe 10 minutes?) then it starts
again.

The circuit in question is one of four ring mains in the house, it
supplies the sitting room, one bedroom , a socket in the hall, in the
conservatory and the dressing room. generally lightly loaded - a few
table/standard lamps, TV, VCR, DVD etc.

Whilst investigating this problem I noticed that when this circuit was
switched on the disc on the meter started fair whizzing round - 30
rev/minute up from the say about 3 rev/minute is was doing normally.

My quick calcs indicate that 30 rev/min implies something like 10kW/h
being consumed - around 40A? , or have I made some big boo-boo?

Anyway, there is nothing on the circuit drawing anything like that (no
we don't have any secret electric showers, or unknown immersion heaters
etc.) These symptoms continue to occur once everything on the circuit
has been disconnected.

I've not had time today to investigate this more thoroughly, the circuit
is isolated now via the MCB pending time tomorrow.

I wonder if next door's cannabis plants are now in the dark?

So, my thought so far is that there is some fault in the fixed wiring,
causing a high current draw, and that the MCB is faulty in some way,
hence the noise rather than tripping.

Does the above sound a reasonable diagnosis?

It's very unlikely that a fault in the wiring dissipating 10kW
will stay that way for more than a few seconds. It will quickly
burn out, either sort or open circuit. Besides which, you'd be
quite likely to notice 10kW of heat coming into the house from
an unexpected location.

I would not be surprised at a 30A breaker making a noise at 40A,
and I wouldn't immediately assume something wrong with the breaker
in this case. It's probably right on the virge of tripping.

Seems like you need to find what the high load is, which your
meter is also confirming.

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

In article ,
chris French wrote:
So, my thought so far is that there is some fault in the fixed wiring,
causing a high current draw, and that the MCB is faulty in some way,
hence the noise rather than tripping.

Does the above sound a reasonable diagnosis?

I can't really think of a fault which would result in a very high current
draw on the circuit with no load applied to it. I'd say even with the
smaller ECC used on early rings and one end disconnected and shorted to
line (the worst possible fault condition) it should still trip the MCB.

But a heavy current draw like this should be easily found with a simple
DVM - after disconnecting the ring from the CU of course.

--
*Great groups from little icons grow *

Dave Plowman London SW
To e-mail, change noise into sound.

In message , Andrew Gabriel
writes
In article ,
chris French writes:

Heard a sort of chattering sound from the MCB (30A) supplying one of the
ring mains in our house this afternoon. Turn of the MCB, turn it back on
again, all is ok for a little while (maybe 10 minutes?) then it starts
again.
snip
Whilst investigating this problem I noticed that when this circuit was
switched on the disc on the meter started fair whizzing round - 30
rev/minute up from the say about 3 rev/minute is was doing normally.

My quick calcs indicate that 30 rev/min implies something like 10kW/h
being consumed - around 40A? , or have I made some big boo-boo?

Anyway, there is nothing on the circuit drawing anything like that (no
we don't have any secret electric showers, or unknown immersion heaters
etc.) These symptoms continue to occur once everything on the circuit
has been disconnected.


I wonder if next door's cannabis plants are now in the dark?


:-)

Detached house, unless someone has burrowed into the house to connect
something up it's pretty safe to say that it's in our property
somewhere.

So, my thought so far is that there is some fault in the fixed wiring,
causing a high current draw, and that the MCB is faulty in some way,
hence the noise rather than tripping.

Does the above sound a reasonable diagnosis?

It's very unlikely that a fault in the wiring dissipating 10kW
will stay that way for more than a few seconds. It will quickly
burn out, either sort or open circuit. Besides which, you'd be
quite likely to notice 10kW of heat coming into the house from
an unexpected location.


TBh, that was what I was thinking.

I would not be surprised at a 30A breaker making a noise at 40A,
and I wouldn't immediately assume something wrong with the breaker
in this case. It's probably right on the virge of tripping.

Seems like you need to find what the high load is, which your
meter is also confirming.

Well yes, that was indeed my thought, problem is, I'm at a loss as to
what/where it could be, there is nothing in the house that I can think
of that could possibly be drawing that sort of current, that isn't
already accounted for. OK it's an old installation, and I still haven't
got my head round all of it's idiosyncrasies, but this is very odd.

At the moment I'm flummoxed, but I've got the house to my self now till
mid afternoon so will try and investigate some more.
--
Chris French

In message , "Dave Plowman (News)"
writes
In article ,
chris French wrote:
So, my thought so far is that there is some fault in the fixed wiring,
causing a high current draw, and that the MCB is faulty in some way,
hence the noise rather than tripping.

Does the above sound a reasonable diagnosis?

I can't really think of a fault which would result in a very high current
draw on the circuit with no load applied to it. I'd say even with the
smaller ECC used on early rings and one end disconnected and shorted to
line (the worst possible fault condition) it should still trip the MCB.

But a heavy current draw like this should be easily found with a simple
DVM - after disconnecting the ring from the CU of course.

OK, how would I go about it? I've got cheapy multimeter.
--
Chris French

In message , nightjar
writes

"chris French" wrote in message
k...
...
I can check out the MCB by swopping it with others in the CU I guess, if
it is faulty then I'm not sure if replacing it is going to be a problem or
not.

The CU is a pretty old Crabtree one, you can see a couple of piccies he

http://galoka.adsl24.co.uk/temp/IMG_0085.jpg
http://galoka.adsl24.co.uk/temp/IMG_0088.jpg

Does anyone know if I will be able to find something to fit?

They look the same type as used in a couple of my factory distribution
boards and they haven't been available for the past ten years.


OK, thanks Colin, I was sort of expecting that. I'll worry about that
bit if I need too.
--
Chris French

On Oct 17, 10:29 am, chris French
wrote:
In message , "Dave Plowman (News)"
writes

In article ,
chris French wrote:
So, my thought so far is that there is some fault in the fixed wiring,
causing a high current draw, and that the MCB is faulty in some way,
hence the noise rather than tripping.

Does the above sound a reasonable diagnosis?

I can't really think of a fault which would result in a very high current
draw on the circuit with no load applied to it. I'd say even with the
smaller ECC used on early rings and one end disconnected and shorted to
line (the worst possible fault condition) it should still trip the MCB.

But a heavy current draw like this should be easily found with a simple
DVM - after disconnecting the ring from the CU of course.

OK, how would I go about it? I've got cheapy multimeter.
--
Chris French

Hi

Disconnect everything from the ring, and disconnect the ring from the
CU.

With your multimeter set to the ohms range, do the following
measurements:-

LL (should read low)
NN (should read low)
EE (should read low)

That proves your ring is intact from end to end.

Next, on either of the cables measure between LE, LN, and EN. They
should all read open circuit.

If you get any low resistance readings, perform the same test on the
other leg of the ring as whichever gives the lowest reading indicates
the fault is nearer that end of the ring.

Steve

chris French wrote:
In message , "Dave Plowman (News)"
writes

But a heavy current draw like this should be easily found with a simple
DVM - after disconnecting the ring from the CU of course.

OK, how would I go about it? I've got cheapy multimeter.

Personally I would prefer to start by using a clamp meter on the running
circuit - clamp round the live(s) at the exit from the MCB and take a
direct reading of the current. This will verify what the real load is.

One test with a DVM would be to disconnect the circuit (live and
neutral) at the CU and then measure the resistance between live and
neutral.

If the circuit was drawing 40A at 240V, then you may see a resistance as
low as 6 ohms. However this does assume that the load you are seeing
will be visible at the low voltage of the DVM, and also that it is
purely resistive[1].

If you can see the load with the DVM like this, then it ought to be a
case of just breaking the circuit at various places until you isolate
where it is. So if it is a ring for example, splitting in the middle and
seeing which leg of it at the CU shows the low impedance load would
immediately eliminate half the circuit.

[1] A large reactive load would be an interesting possibility in that it
would not need to be accompanied by a large power dissipation. However
your electricity meter ought not record this as power consumption.


--
Cheers,

John.

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

Have you recently moved to this house? A massive power consumption
like this would be reflected in your electricity bills.

A possible explanation is that the wiring is very different to what
you think it is - and a heavy load of this sort is normal (e.g.
shower, cooker, storage heaters) - or the wiring is so mad that a
heavy current device is actually supplied through 2 different MCB's.

I would start by thoroughly mapping each circuit from the consumer
unit. All mcb's off - check every single socket, light and appliance
is without power (in case something has been wired before the mcb's!).
Check zero consumption on the meter. Then one mcb at once, verify
every single socket, light & appliance - would be a good time to use a
plug-in polarity & earth tester.

If the behaviour persists, and there's a massive current load on only
one socket ring with no plugged in loads, and the behaviour is
repeatable by switching that mcb with all others isolated - first
panic, then consider opening up sockets, disconnecting parts of the
ring etc.

In message .com,
" writes
Have you recently moved to this house? A massive power consumption
like this would be reflected in your electricity bills.

No we've been here 2 1/2 years, certainly we have not had 10Kw/h running
continuously since then. Certainly the bills/my meter records don't
reflect this. AFAIK this just started happening yesterday.


A possible explanation is that the wiring is very different to what
you think it is - and a heavy load of this sort is normal (e.g.
shower, cooker, storage heaters) - or the wiring is so mad that a
heavy current device is actually supplied through 2 different MCB's.


Thing is we don't have many heavy loads. Cooker (which is isolated a sit
is a 'spare') and Immersion Heater - which is, as it usually is, turned
off. No electric shower, storage heater etc.

There di use to be storage heaters before our time, and one thing I did
think about was that ther was one somewhere that had sparked into life.
But if there is then I certainly have never seen it.

It's all very odd (and yep, if I was answering this thread I'd be saying
- 'he's got somethign somewhere running he's forgotten about....).

I would start by thoroughly mapping each circuit from the consumer
unit. All mcb's off - check every single socket, light and appliance
is without power (in case something has been wired before the mcb's!).
Check zero consumption on the meter. Then one mcb at once, verify
every single socket, light & appliance - would be a good time to use a
plug-in polarity & earth tester.


I have checked out what is on which circuit before, but as part of
today's checks I'm having another check.

If the behaviour persists, and there's a massive current load on only
one socket ring with no plugged in loads, and the behaviour is
repeatable by switching that mcb with all others isolated - first
panic, then consider opening up sockets, disconnecting parts of the
ring etc.


Thanks for everyones comments and suggestions/instructions, Turning off
now, I'll be reporting back
--
Chris French

In message . com,
stevelup writes
Hi

Disconnect everything from the ring, and disconnect the ring from the
CU.

With your multimeter set to the ohms range, do the following
measurements:-

LL (should read low)
NN (should read low)
EE (should read low)

That proves your ring is intact from end to end.

Next, on either of the cables measure between LE, LN, and EN. They
should all read open circuit.

If you get any low resistance readings, perform the same test on the
other leg of the ring as whichever gives the lowest reading indicates
the fault is nearer that end of the ring.

Thanks for that Steve.

A quick lunch break update.

OK, checked over the circuits again, but could not find anything lurking
in the woodpile.

So been trying the above tests.

Looks like a Live to Earth fault- Low resistance/continuity between Live
and Earth. I think I've now managed to narrow down the section of the
ring that the fault is on - there is probably a junction box lurking
somewhere as there is a spur off that probably comes off this leg
somewhere.

I'm thinking that maybe my RCD isn't doing it's job properly? (We have a
TT earth system with just one main incoming RCD - about as old looking
as the CU) The test button works ok though.
--
Chris French

chris French wrote:

I'm thinking that maybe my RCD isn't doing it's job properly? (We have a
TT earth system with just one main incoming RCD - about as old looking
as the CU) The test button works ok though.

Are you sure it is a RCD and not an older "voltage operated" ELCB?

There is a picture of a common one he
http://wiki.diyfaq.org.uk/index.php?title=RCD#ELCB

There are also details of how to test the RCD, if it is a RCD.


--
Cheers,

John.

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

On 17 Oct, 14:27, chris French
wrote:
In message . com,
stevelup writes





Hi

Disconnect everything from the ring, and disconnect the ring from the
CU.

With your multimeter set to the ohms range, do the following
measurements:-

LL (should read low)
NN (should read low)
EE (should read low)

That proves your ring is intact from end to end.

Next, on either of the cables measure between LE, LN, and EN. They
should all read open circuit.

If you get any low resistance readings, perform the same test on the
other leg of the ring as whichever gives the lowest reading indicates
the fault is nearer that end of the ring.

Thanks for that Steve.

A quick lunch break update.

OK, checked over the circuits again, but could not find anything lurking
in the woodpile.

So been trying the above tests.

Looks like a Live to Earth fault- Low resistance/continuity between Live
and Earth. I think I've now managed to narrow down the section of the
ring that the fault is on - there is probably a junction box lurking
somewhere as there is a spur off that probably comes off this leg
somewhere.

I'm thinking that maybe my RCD isn't doing it's job properly? (We have a
TT earth system with just one main incoming RCD - about as old looking
as the CU) The test button works ok though.
--
Chris French- Hide quoted text -

- Show quoted text -

Are you sure it is an RCD and not a VOELCB?
Have you or anyone else drilled any holes in walls or driven any nails
into one lately?
A defective immersion heater might also be a candidate for
consideration. It should not be supplied from a ring final circuit but
the possibility of it happening does exist.

Hi,

I'm thinking that maybe my RCD isn't doing it's job properly? (We have
a TT earth system with just one main incoming RCD - about as old
looking as the CU) The test button works ok though.

I would be inclined to think that as well. 10KW is a lot of energy -
probably enough to meet the entire heating needs of a medium sized house
at this time of year and I have to wonder where it is going without you
noticing something at least getting hot and probably catching fire.

One place that you might be able to loose that kind of energy for a
while would be heating the ground around your earth rod.

Martin.

One place that you might be able to loose that kind of energy for a
while would be heating the ground around your earth rod.

Switch everything off, lift the earth connection in the CU, switch on
- does fault persist?

(Immediately reinstate that earth!)

In message , John Rumm
writes
chris French wrote:

I'm thinking that maybe my RCD isn't doing it's job properly? (We
have a TT earth system with just one main incoming RCD - about as old
looking as the CU) The test button works ok though.

Are you sure it is a RCD and not an older "voltage operated" ELCB?

No I'm not.

There is a picture of a common one he
http://wiki.diyfaq.org.uk/index.php?title=RCD#ELCB

In fact it looks exactly like that.....
--
Chris French

In article ,
John Rumm writes:
chris French wrote:

I'm thinking that maybe my RCD isn't doing it's job properly? (We have a
TT earth system with just one main incoming RCD - about as old looking
as the CU) The test button works ok though.

Are you sure it is a RCD and not an older "voltage operated" ELCB?

If that's the case, then the leak could be via a water main or
similar to earth (you won't get 40A or anything like through a
VOELCB). Either this water main (or whatever) is not connected
to the house earthing (and has virtually full mains voltage on
it), or it is connected to the house earthing but has an
overlapping resistance area with the VOELCB earth rod, preventing
the VOELCB from working.

Another option is the VOELCB has become disconnected from the
house earthing, either due to an internal fault or deliberate
action (possibly to prevent tripping in the past).

Probably other options too, but those two spring to mind as
matching the symptoms described.

Beware, as you may have live metalwork around the house.

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

chris French wrote:
In message , John Rumm
writes
chris French wrote:

I'm thinking that maybe my RCD isn't doing it's job properly? (We
have a TT earth system with just one main incoming RCD - about as
old looking as the CU) The test button works ok though.

Are you sure it is a RCD and not an older "voltage operated" ELCB?

No I'm not.

There is a picture of a common one he
http://wiki.diyfaq.org.uk/index.php?title=RCD#ELCB

In fact it looks exactly like that.....

Aha, the plot thickens... ;-)

Like Andy said these can fail to operate for a number of reasons. So it
is possible to have a live to earth fault and not have it trip.

First job sounds like finding the live to earth fault. You can worry
about replacing the ELCB with something else after!


--
Cheers,

John.

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

In message , John Rumm
writes
chris French wrote:
In message , John Rumm
writes
chris French wrote:

I'm thinking that maybe my RCD isn't doing it's job properly? (We
have a TT earth system with just one main incoming RCD - about as
old looking as the CU) The test button works ok though.

Are you sure it is a RCD and not an older "voltage operated" ELCB?

No I'm not.

There is a picture of a common one he
http://wiki.diyfaq.org.uk/index.php?title=RCD#ELCB

In fact it looks exactly like that.....

Aha, the plot thickens... ;-)

It's an old house, the plot is always thick....


At some point I did consider that it could be an ELCB, but seemed to
forget about the option at this point.

Like Andy said these can fail to operate for a number of reasons. So it
is possible to have a live to earth fault and not have it trip.

First job sounds like finding the live to earth fault. You can worry
about replacing the ELCB with something else after!


I think I've found the fault, after much rummaging behind sockets.

A live wire in one has a small bit of damaged insulation - just like a
cut or maybe getting trapped and damaged at some point - this must have
been in contact with an earth wire (old-ish installation - no sleeving)
or maybe the backbox. There was a little tiny bit of what looked like
heat damage, but only slight, I was expecting a bit more.

Just need to put everything back now, and see if it's ok.


--
Chris French

Hope you have it sorted Chris. Given the potential seriousness, a
proper wiring regs full test of all circuits might be advisable.

On Oct 18, 12:12 pm, chris French
wrote:
I think I've found the fault, after much rummaging behind sockets.

A live wire in one has a small bit of damaged insulation - just like a
cut or maybe getting trapped and damaged at some point - this must have
been in contact with an earth wire (old-ish installation - no sleeving)
or maybe the backbox. There was a little tiny bit of what looked like
heat damage, but only slight, I was expecting a bit more.

Just need to put everything back now, and see if it's ok.

Might be worth fitting an RCD instead of the ELCB.

Though Part P probably forbids doing it yourself without hassle :|

cheers,
Pete.

chris French wrote:

A live wire in one has a small bit of damaged insulation - just like a
cut or maybe getting trapped and damaged at some point - this must have
been in contact with an earth wire (old-ish installation - no sleeving)
or maybe the backbox. There was a little tiny bit of what looked like
heat damage, but only slight, I was expecting a bit more.

Just need to put everything back now, and see if it's ok.

Given the nature of the fault I would suggest retesting with an
insulation resistance tester if you can borrow one. That way you should
find any other latent problems of that nature.

--
Cheers,

John.

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

In message , Andrew Gabriel
writes
In article ,
John Rumm writes:
chris French wrote:

I'm thinking that maybe my RCD isn't doing it's job properly? (We have a
TT earth system with just one main incoming RCD - about as old looking
as the CU) The test button works ok though.

Are you sure it is a RCD and not an older "voltage operated" ELCB?

If that's the case, then the leak could be via a water main or
similar to earth (you won't get 40A or anything like through a
VOELCB). Either this water main (or whatever) is not connected
to the house earthing (and has virtually full mains voltage on
it), or it is connected to the house earthing but has an
overlapping resistance area with the VOELCB earth rod, preventing
the VOELCB from working.

Another option is the VOELCB has become disconnected from the
house earthing, either due to an internal fault or deliberate
action (possibly to prevent tripping in the past).

Probably other options too, but those two spring to mind as
matching the symptoms described.

Beware, as you may have live metalwork around the house.


Well, thanks to everyone's help. The socket live earth fault does seem
to have been the problem. Rectified the problem, all seem to be fine
now. Replaced a couple of falling part 30-40 year old socket faceplates.

John, you suggested borrowing an insulation tester - if I had any idea
where to borrow one I might, but TBH this does seem to have been a one
off, the rest of what I've seen generally seems ok

Re your above comments Andrew, well the metal work around the house
seemed to be ok. The isn't any main bonding of the water/gad pipes at
the moment. The VOELCB seems to be connected properly, I can't see any
earth connections that bypass it. It has two 'outgoing' earth
connections.

One, to (presumably - I need to remove the base of an old climbing plant
to find it) a buried earth rod, the second looks older - connects to an
external copper pipe. This looks like an old gas pipe. It rises from the
solid kitchen floor, goes out through the wall, runs along the outside,
goes back inside to the utility room, where it terminates in what looks
like a capped off gas cock.

Anyway sorting out the meter/CU area has been on the job list for a
while. It's probably up to 40 years old, the main CU is chockerblock and
there is the typical hotpotch of extra switch fuses etc. A new bigger
CU, a main RCD, sorting out the main earth bonding etc. Probably
starting with replacing the VOELCB with an RCD to give more space for
the new CU, partly because that can go elsewhere on the mounting board -
replacing a great big F-off metal main switch - there presumably because
the house has a 3 phase supply. Though only 1 phase is used.


--
Chris French

chris French wrote:

John, you suggested borrowing an insulation tester - if I had any idea
where to borrow one I might, but TBH this does seem to have been a one
off, the rest of what I've seen generally seems ok

I have one in SE Essex if that is any use... Failing that a hire shop
may be able to help.

The reason for suggesting it was that if there was one fault of this
type it might indicate that other similar faults may be lurking. A high
voltage resistance test will shake out the ones that a multimeter will
not find.

Re your above comments Andrew, well the metal work around the house
seemed to be ok. The isn't any main bonding of the water/gad pipes at
the moment. The VOELCB seems to be connected properly, I can't see any
earth connections that bypass it. It has two 'outgoing' earth connections.

There are a number of ways of hooking these things up. Some a quite
sophisticated with main and sense electrodes, but more commonly you just
have them inline with the main earth connection to a single electrode.

One, to (presumably - I need to remove the base of an old climbing plant
to find it) a buried earth rod, the second looks older - connects to an
external copper pipe. This looks like an old gas pipe. It rises from the
solid kitchen floor, goes out through the wall, runs along the outside,
goes back inside to the utility room, where it terminates in what looks
like a capped off gas cock.

Using a gas pipe was not uncommon. I used to have one in my house which
just used the gas pipe as a main earth. The danger is that these days
they may end up replacing large swathes of pipe with plastic and this
can interfere with the operation of your earthing.

Anyway sorting out the meter/CU area has been on the job list for a
while. It's probably up to 40 years old, the main CU is chockerblock and
there is the typical hotpotch of extra switch fuses etc. A new bigger
CU, a main RCD, sorting out the main earth bonding etc. Probably
starting with replacing the VOELCB with an RCD to give more space for
the new CU, partly because that can go elsewhere on the mounting board -
replacing a great big F-off metal main switch - there presumably because
the house has a 3 phase supply. Though only 1 phase is used.

In circumstances like that it can often work out simpler to install two
CUs fed via split tails from a main switch. You can stick an ordinary
100mA trip RCD in one for all the lights and other circuits that do not
need direct contact protection, and then have a 30mA trip RCD in a
second CU for the power circuits. Often works out cheaper than having a
£100 time delayed RCD cascaded in the same CU as the smaller threshold one.

--
Cheers,

John.

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

In message , John Rumm
writes
chris French wrote:

John, you suggested borrowing an insulation tester - if I had any
idea where to borrow one I might, but TBH this does seem to have been
a one off, the rest of what I've seen generally seems ok

I have one in SE Essex if that is any use... Failing that a hire shop
may be able to help.

Thanks, but we are in the middle of Cambridgeshire. I might investigate
hire options.

One, to (presumably - I need to remove the base of an old climbing
plant to find it) a buried earth rod, the second looks older -
connects to an external copper pipe. This looks like an old gas pipe.

Using a gas pipe was not uncommon. I used to have one in my house which
just used the gas pipe as a main earth. The danger is that these days
they may end up replacing large swathes of pipe with plastic and this
can interfere with the operation of your earthing.

It's unlikely this bit of pipe would get replaced with plastic (more
like just removed all together), but anyway, we have a proper earth
rod.

Anyway sorting out the meter/CU area has been on the job list for a
while. It's probably up to 40 years old, the main CU is chockerblock
and there is the typical hotpotch of extra switch fuses etc. A new
bigger CU, a main RCD, sorting out the main earth bonding etc.
Probably starting with replacing the VOELCB with an RCD to give more
space for the new CU, partly because that can go elsewhere on the
mounting board - replacing a great big F-off metal main switch -
there presumably because the house has a 3 phase supply. Though only
1 phase is used.

In circumstances like that it can often work out simpler to install two
CUs fed via split tails from a main switch. You can stick an ordinary
100mA trip RCD in one for all the lights and other circuits that do not
need direct contact protection, and then have a 30mA trip RCD in a
second CU for the power circuits. Often works out cheaper than having a
£100 time delayed RCD cascaded in the same CU as the smaller threshold one.

Ahh yes, that's a good suggestion, thanks.
--
Chris French

Thanks, but we are in the middle of Cambridgeshire...

Ah - you're fixing fenland wiring!

This may explain much.

I removed a wiring run from actually inside the trough of the
rainwater guttering in my old fenland bungalow.

wrote:

I removed a wiring run from actually inside the trough of the
rainwater guttering in my old fenland bungalow.

Novel approach to keeping it cool perhaps!


--
Cheers,

John.

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

In message .com,
" writes

Thanks, but we are in the middle of Cambridgeshire...

Ah - you're fixing fenland wiring!


Not quite on the fens, we are high up (approx 10m above sea level)
--
Chris French