A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We have
an upstairs ring main, downstairs ring main and a kitchen ring main, all of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does
*not* trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring shows
the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " " "
"
N-E = " " " " " "
"

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed

Mogweed wrote:
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We
have an upstairs ring main, downstairs ring main and a kitchen ring
main, all of which are protected by the RCD, and the problem is the
kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD
trips (plugging the same things into either upstairs or downstairs
rings does *not* trip it).

Splitting the ring at the CU and using a proper Megger (500v
insulation resistance tester, not just a multimeter) to test each leg
of the ring shows the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " "
" "
N-E = " " " " "
" "

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed

Are you 100% sure you don't have a short?

Have you been capping back the cable into chases, Screwed down floor
boards?
--
Sir Benjamin Middlethwaite

"The3rd Earl Of Derby" wrote in message
k...
Mogweed wrote:
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We
have an upstairs ring main, downstairs ring main and a kitchen ring
main, all of which are protected by the RCD, and the problem is the
kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD
trips (plugging the same things into either upstairs or downstairs
rings does *not* trip it).

Splitting the ring at the CU and using a proper Megger (500v
insulation resistance tester, not just a multimeter) to test each leg
of the ring shows the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " "
" "
N-E = " " " " "
" "

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed

Are you 100% sure you don't have a short?

Have you been capping back the cable into chases, Screwed down floor
boards?
--
Sir Benjamin Middlethwaite


You have to believe your instruments so I can only go on what the megger
tells me, and that says that there is no short - tried shorting the test
leads and the meter swings right over to 0 ohms so the megger seems to be
working OK. Cables capped - and chases plastered over ( Some
floorboards screwed back down - but megger shows no shorts.

Mogweed.

Mogweed wrote:
"The3rd Earl Of Derby" wrote in message
k...
Mogweed wrote:
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit.
We have an upstairs ring main, downstairs ring main and a kitchen
ring main, all of which are protected by the RCD, and the problem
is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill
or whatever) is plugged into *any* socket on the kitchen ring, the
RCD trips (plugging the same things into either upstairs or
downstairs rings does *not* trip it).

Splitting the ring at the CU and using a proper Megger (500v
insulation resistance tester, not just a multimeter) to test each
leg of the ring shows the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " "
" "
N-E = " " " " "
" "

so no short-circuits, but yet the RCD trips. What's the problem -
more importantly, what's the solution to the problem? )

TIA,

Mogweed

Are you 100% sure you don't have a short?

Have you been capping back the cable into chases, Screwed down floor
boards?
--
Sir Benjamin Middlethwaite


You have to believe your instruments so I can only go on what the
megger tells me, and that says that there is no short - tried
shorting the test leads and the meter swings right over to 0 ohms so
the megger seems to be working OK. Cables capped - and chases
plastered over ( Some floorboards screwed back down - but
megger shows no shorts.

Mogweed.

Take the kitchen strap out of the CU attach a battery&bulb L to +, - to
bulb and bulb to N and see if the bulb lights? do this on the E to L and E
to N.
If it lights you have a short if not then start looking at CU

--
Sir Benjamin Middlethwaite

"The3rd Earl Of Derby" wrote in message
k...
Mogweed wrote:
"The3rd Earl Of Derby" wrote in message
k...
Mogweed wrote:

Are you 100% sure you don't have a short?

Have you been capping back the cable into chases, Screwed down floor
boards?
--
Sir Benjamin Middlethwaite


You have to believe your instruments so I can only go on what the
megger tells me, and that says that there is no short - tried
shorting the test leads and the meter swings right over to 0 ohms so
the megger seems to be working OK. Cables capped - and chases
plastered over ( Some floorboards screwed back down - but
megger shows no shorts.

Mogweed.

Take the kitchen strap out of the CU attach a battery&bulb L to +, - to
bulb and bulb to N and see if the bulb lights? do this on the E to L and E
to N.
If it lights you have a short if not then start looking at CU

--
Sir Benjamin Middlethwaite


Cheers Sir Benjamin, I'll give it a go.

Mogweed.

The3rd Earl Of Derby wrote:
Take the kitchen strap out of the CU attach a battery&bulb L to +, - to
bulb and bulb to N and see if the bulb lights? do this on the E to L and E
to N.
If it lights you have a short if not then start looking at CU

Why would using a battery and bulb be a better tester than a proper
instrument?

alex

Mogweed wrote:

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

Have you checked for a misplaced neutral?
'Tis a common mistake on a split load CU...

Lee

--
Email address is valid, but is unlikely to be read.

"Lee" wrote in message
...
Mogweed wrote:

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

Have you checked for a misplaced neutral?
'Tis a common mistake on a split load CU...

Lee

Ah, now then, I haven't checked for that - mainly because I didn't know that
a neutral could be misplaced. They all go to a common bar don't they?

Mogweed.

On or around Fri, 11 Nov 2005 19:21:12 -0000, "Mogweed"
mused:


"Lee" wrote in message
...
Mogweed wrote:

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

Have you checked for a misplaced neutral?
'Tis a common mistake on a split load CU...

Lee

Ah, now then, I haven't checked for that - mainly because I didn't know that
a neutral could be misplaced. They all go to a common bar don't they?

Nope, seperate neutral bars for RCD and non-RCD circuits. Did the
circuit ever work? If it did, then the misplaced neutral idea is wrong
as that would trip the RCD from day one.
--
| Stuart @ SJW Electrical. Please Reply to group. |

"Lurch" wrote in message
...
On or around Fri, 11 Nov 2005 19:21:12 -0000, "Mogweed"
mused:


"Lee" wrote in message
...
Mogweed wrote:

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

Have you checked for a misplaced neutral?
'Tis a common mistake on a split load CU...

Lee

Ah, now then, I haven't checked for that - mainly because I didn't know
that
a neutral could be misplaced. They all go to a common bar don't they?

Nope, seperate neutral bars for RCD and non-RCD circuits. Did the
circuit ever work? If it did, then the misplaced neutral idea is wrong
as that would trip the RCD from day one.

I read this as all the time since rewiring

On Fri, 11 Nov 2005 18:58:17 GMT, Lee
wrote:

Mogweed wrote:

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

Have you checked for a misplaced neutral?
'Tis a common mistake on a split load CU...

That does sound like the problem - possibly a neutral swapped with an
earth, otherwise the RCD wouldn't trip with a non-earthed item such as
a radio.

--
Frank Erskine

In message , Frank Erskine
writes
On Fri, 11 Nov 2005 18:58:17 GMT, Lee
wrote:

Mogweed wrote:

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

Have you checked for a misplaced neutral?
'Tis a common mistake on a split load CU...

That does sound like the problem - possibly a neutral swapped with an
earth, otherwise the RCD wouldn't trip with a non-earthed item such as
a radio.

Yes it would, if the kitchen ring neutral has been returned to the
non-RCD busbar. A common and easy to make mistake.

--
steve

In article , says...
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We have
an upstairs ring main, downstairs ring main and a kitchen ring main, all of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does
*not* trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring shows
the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " " "
"
N-E = " " " " " "
"

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed




As a portable radio, which presumably is double insulated, is also
tripping it, it suggests that the fault is not on the earth, so I would
guess that there is either a neutral leg or a live leg connected to the
wrong side of the RCD.

Alternatively, if it is a Wylex S/L board, there have been quite a few
faulty RCDs coming from them of late - at least in our neck of the woods.
Doesn't explain why it is only one ring which causes the problem though.
I'd check first that the ring is terminated (both conductors, both legs)
on the correct side of the RCD first.

"Gary Cavie" wrote in message
t...
In article , says...
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We
have
an upstairs ring main, downstairs ring main and a kitchen ring main, all
of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does
*not* trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring
shows
the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " "
"
"
N-E = " " " " "
"
"

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed




As a portable radio, which presumably is double insulated, is also
tripping it, it suggests that the fault is not on the earth, so I would
guess that there is either a neutral leg or a live leg connected to the
wrong side of the RCD.

Alternatively, if it is a Wylex S/L board, there have been quite a few
faulty RCDs coming from them of late - at least in our neck of the woods.
Doesn't explain why it is only one ring which causes the problem though.
I'd check first that the ring is terminated (both conductors, both legs)
on the correct side of the RCD first.

Thanks Gary, I'll check that - and it is actually a Wylex CU but as you say,
if it was a faulty RCD it should show up on the other rings too.

Mogweed.

On Fri, 11 Nov 2005 18:36:00 -0000, "Mogweed"
wrote:

A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We have
an upstairs ring main, downstairs ring main and a kitchen ring main, all of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does
*not* trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring shows
the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " " "
"
N-E = " " " " " "
"

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed

Faulty RCD? If they are the same value try swapping two and see if the
fault moves.

sponix

"--s-p-o-n-i-x--" wrote in message
...
On Fri, 11 Nov 2005 18:36:00 -0000, "Mogweed"
wrote:

A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We have
an upstairs ring main, downstairs ring main and a kitchen ring main, all
of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does
*not* trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring
shows
the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " "
"
"
N-E = " " " " "
"
"

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

TIA,

Mogweed

Faulty RCD? If they are the same value try swapping two and see if the
fault moves.

sponix

Thanks sponix but I think you're thinking of the MCBs rather than the RCD
)

Mogweed.

On Fri, 11 Nov 2005 19:44:28 -0000, "Mogweed"
wrote:

Faulty RCD? If they are the same value try swapping two and see if the
fault moves.

sponix

Thanks sponix but I think you're thinking of the MCBs rather than the RCD
)

Well, I have had plug in RCDs that trip when loaded with non-earthed
appliances..

sponix

On or around Fri, 11 Nov 2005 19:27:25 +0000, --s-p-o-n-i-x--
mused:

Faulty RCD? If they are the same value try swapping two and see if the
fault moves.

A split load board installed by a mate with 2 identical RCD's in?
Stick to whatever it is you do normally.
--
| Stuart @ SJW Electrical. Please Reply to group. |

On Fri, 11 Nov 2005 20:19:52 +0000, Lurch
wrote:

On or around Fri, 11 Nov 2005 19:27:25 +0000, --s-p-o-n-i-x--
mused:

Faulty RCD? If they are the same value try swapping two and see if the
fault moves.

A split load board installed by a mate with 2 identical RCD's in?
Stick to whatever it is you do normally.

So you are saying one RCD protects the whole house? That's a pretty
stupid idea in addition to the fact it contravenes 16th edition
regulations.

sponix

On or around Fri, 11 Nov 2005 20:37:35 +0000, --s-p-o-n-i-x--
mused:

On Fri, 11 Nov 2005 20:19:52 +0000, Lurch
wrote:

On or around Fri, 11 Nov 2005 19:27:25 +0000, --s-p-o-n-i-x--
mused:

Faulty RCD? If they are the same value try swapping two and see if the
fault moves.

A split load board installed by a mate with 2 identical RCD's in?
Stick to whatever it is you do normally.

So you are saying one RCD protects the whole house? That's a pretty
stupid idea in addition to the fact it contravenes 16th edition
regulations.

Dr Dimwit?

It doesn't contravene BS7671, under certain circumstances, and a
standard slit load board has one RCD covering *some* circuits, not
all. I suggest you read up on plit load boards before talking more
********.
--
| Stuart @ SJW Electrical. Please Reply to group. |

Lurch wrote:
On or around Fri, 11 Nov 2005 20:37:35 +0000, --s-p-o-n-i-x--
mused:

So you are saying one RCD protects the whole house? That's a pretty
stupid idea in addition to the fact it contravenes 16th edition
regulations.

It doesn't contravene BS7671, under certain circumstances, and a
standard slit load board has one RCD covering *some* circuits, not
all. I suggest you read up on plit load boards before talking more
********.

I've seen plenty of non-split-load CU's for sale complete with RCDs at
the likes of Screwfix (eg http://tinyurl.com/bb2ej); I understand it's
not a good idea to have all circuits protected by an RCD, but when/why
would it be actually against regs to fit one of these as a whole-house CU?

David

Lurch wrote:

and a
standard slit load board has one RCD covering *some* circuits, not
all. I suggest you read up on plit load boards before talking more
********.

Might be worth adding that you will need RCD protection for *all*
circuits if you have TT earthing.


--
Cheers,

John.

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

Mogweed was thinking very hard :
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We have an
upstairs ring main, downstairs ring main and a kitchen ring main, all of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does *not*
trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring shows
the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " " " "
N-E = " " " " " " "

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )

It sounds as if you/he have managed to mix up the ring circuits, such
that - one of the circuits protected by RCD is mixed up with one not on
the RCD. Thus causing an unbalanced load on the RCD, hence it tripping.

Try disconnecting each pair of 2.5mm in turn and make sure you have
continuity between each pair of both reds and blacks.


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Fri, 11 Nov 2005 19:58:08 GMT, "Harry Bloomfield"
wrote:


Try disconnecting each pair of 2.5mm in turn and make sure you have
continuity between each pair of both reds and blacks.

Or even browns and blues :-)

--
Frank Erskine

Frank Erskine has brought this to us :
On Fri, 11 Nov 2005 19:58:08 GMT, "Harry Bloomfield"
wrote:


Try disconnecting each pair of 2.5mm in turn and make sure you have
continuity between each pair of both reds and blacks.

Or even browns and blues :-)

Not if he is trying to circumvent 'Part P' :-)

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Harry Bloomfield wrote:
Frank Erskine has brought this to us :
On Fri, 11 Nov 2005 19:58:08 GMT, "Harry Bloomfield"
wrote:


Try disconnecting each pair of 2.5mm in turn and make sure you have
continuity between each pair of both reds and blacks.

Or even browns and blues :-)

Not if he is trying to circumvent 'Part P' :-)

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Not necessarily - brown and blue cable was on sale before Part P was in
force.

CRB

"Mogweed" wrote in message
...
A mate of mine has completely rewired our house so everything in the
installation is brand new, including the split-load consumer unit. We have
an upstairs ring main, downstairs ring main and a kitchen ring main, all of
which are protected by the RCD, and the problem is the kitchen ring.

As soon as *anything* (portable radio, halogen lamp, electric drill or
whatever) is plugged into *any* socket on the kitchen ring, the RCD trips
(plugging the same things into either upstairs or downstairs rings does
*not* trip it).

Splitting the ring at the CU and using a proper Megger (500v insulation
resistance tester, not just a multimeter) to test each leg of the ring
shows the following:

L-N = almost infinity resistance (certainly over 1,000Mohms anyway)
L-E = " " " " "
" "
N-E = " " " " "
" "

so no short-circuits, but yet the RCD trips. What's the problem - more
importantly, what's the solution to the problem? )


He has somehow managed to get one or more neutrals wire to the "wrong"
neutral bar in the Consumer Unit. This has been covered many times before so
google is your friend