Hi,

I just installed a new MK Sentry K5686S Split load Consumer Unit and am
having problems with most of the circuits attached to the RCD side of
the consumer unit.

I had four circuits attached to the RCD - Downstairs sockets, upstairs
sockets, garage sockets and the Shower. All of the circuits trip the
RCD apart from the shower. I have temporarily moved these problem
circuits over to the non-rcd side and they are all working fine.

I am suprised that I am having problems, especially with the garage
circuit, as this was only fitted a year ago.

Any ideas on possible causes and how to resolve this problem greatly
appreciated.

Thanks.

"KevCompton" wrote in message
oups.com...
Hi,

I just installed a new MK Sentry K5686S Split load Consumer Unit and am
having problems with most of the circuits attached to the RCD side of
the consumer unit.

I had four circuits attached to the RCD - Downstairs sockets, upstairs
sockets, garage sockets and the Shower. All of the circuits trip the
RCD apart from the shower. I have temporarily moved these problem
circuits over to the non-rcd side and they are all working fine.

I am suprised that I am having problems, especially with the garage
circuit, as this was only fitted a year ago.

Any ideas on possible causes and how to resolve this problem greatly
appreciated.

Thanks.


Slightly OT, but does anyone manufacture an "imbalance" current meter?

"KevCompton" wrote in message
oups.com...
Hi,

I just installed a new MK Sentry K5686S Split load Consumer Unit and am
having problems with most of the circuits attached to the RCD side of
the consumer unit.

I had four circuits attached to the RCD - Downstairs sockets, upstairs
sockets, garage sockets and the Shower. All of the circuits trip the
RCD apart from the shower. I have temporarily moved these problem
circuits over to the non-rcd side and they are all working fine.

I am suprised that I am having problems, especially with the garage
circuit, as this was only fitted a year ago.

Any ideas on possible causes and how to resolve this problem greatly
appreciated.

Thanks.


Make sure that the neutrals for the RCD circuits are on the RCD side and not
the neutral bar of the non-RCD side.

Dave.

KevCompton wrote:

Any ideas on possible causes and how to resolve this problem greatly
appreciated.

The usual problem is wiring the neutral of the RCD protected circuits
back to the non RCD protected neutral bus bar, rather than the dedicated
bus bar for RCD neutrals.

--
Cheers,

John.

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

"KevCompton" wrote in message
oups.com...
Hi,

I just installed a new MK Sentry K5686S Split load Consumer Unit and am
having problems with most of the circuits attached to the RCD side of
the consumer unit.

I had four circuits attached to the RCD - Downstairs sockets, upstairs
sockets, garage sockets and the Shower. All of the circuits trip the
RCD apart from the shower. I have temporarily moved these problem
circuits over to the non-rcd side and they are all working fine.

I am suprised that I am having problems, especially with the garage
circuit, as this was only fitted a year ago.

Any ideas on possible causes and how to resolve this problem greatly
appreciated.

You have connected the neutrals to the wrong connecting strip.
The less likely problem is a faulty RCD but then the shower would trip it
too.

Thanks for all the prompt replies.
I'm 95% sure that I had all the neutrals on the RCD protected neutral
bus bar as I had to swap them over to the non-RCD protected neutral bus
bar to get things working temporarily on the problem circuits. Are
there any other possible reasons?

KevCompton wrote:

Thanks for all the prompt replies.
I'm 95% sure that I had all the neutrals on the RCD protected neutral
bus bar as I had to swap them over to the non-RCD protected neutral bus
bar to get things working temporarily on the problem circuits. Are
there any other possible reasons?

Some CUs come with a link wire between the neutral bus bars. You need to
remove that when using it as a split load unit.

A faulty RCD would be aother possibility. Difficult to test reliably
without an RCD tester though. You could swap it out for another to be sure.

Or it may even be telling you that you have genuine circuit faults! A
quick and simple test would be to check for any neutral to earth shorts
at the CU end of the circuit wires, before you connect them back. You
can get useful information with an ordinary multimeter.

When do you get the trip? If for example you connected a socket circuit
and made sure there was nothing plugged into it, and any equipment
directly connected was disconnected at its FCU, does it still trip with
no load? If not does it then trip with a small load applied (like a
table lamp for example)?


--
Cheers,

John.

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

John Rumm wrote:
KevCompton wrote:

Thanks for all the prompt replies.
I'm 95% sure that I had all the neutrals on the RCD protected neutral
bus bar as I had to swap them over to the non-RCD protected neutral bus
bar to get things working temporarily on the problem circuits. Are
there any other possible reasons?

Some CUs come with a link wire between the neutral bus bars. You need to
remove that when using it as a split load unit.

Hmm, how do you get a neutral feed to it then ? do split CU's have
separate incomers/isolators per side ?

I thought it had a single isolator and separate RCD.

Does it need a dedicated tail per side in this case ?

I can't envisage it as I don't have a split load CU.

P.

wrote in message
ups.com...

John Rumm wrote:
KevCompton wrote:

Thanks for all the prompt replies.
I'm 95% sure that I had all the neutrals on the RCD protected neutral
bus bar as I had to swap them over to the non-RCD protected neutral bus
bar to get things working temporarily on the problem circuits. Are
there any other possible reasons?

Some CUs come with a link wire between the neutral bus bars. You need to
remove that when using it as a split load unit.

Hmm, how do you get a neutral feed to it then ? do split CU's have
separate incomers/isolators per side ?

I thought it had a single isolator and separate RCD.

Does it need a dedicated tail per side in this case ?

I can't envisage it as I don't have a split load CU.


Both the live and neutral go *through* the RCD.

John,

Thanks for the reply.

Some CUs come with a link wire between the neutral bus bars. You need to
remove that when using it as a split load unit.

I removed this prior to installation.

A faulty RCD would be aother possibility. Difficult to test reliably
without an RCD tester though. You could swap it out for another to be sure.

I don't have a spare but, I will ask someone who has a tester to check
it for me.

Or it may even be telling you that you have genuine circuit faults! A
quick and simple test would be to check for any neutral to earth shorts
at the CU end of the circuit wires, before you connect them back. You
can get useful information with an ordinary multimeter.

I will check this when I get chance, is this simply a matter of testing
for continuity between the neutral and earths for each circuit at the
CU?

When do you get the trip? If for example you connected a socket circuit
and made sure there was nothing plugged into it, and any equipment
directly connected was disconnected at its FCU, does it still trip with
no load? If not does it then trip with a small load applied (like a
table lamp for example)?

I will check this when I get chance, thanks for the assistance.

KevCompton wrote:
Thanks for all the prompt replies.
I'm 95% sure that I had all the neutrals on the RCD protected neutral
bus bar as I had to swap them over to the non-RCD protected neutral bus
bar to get things working temporarily on the problem circuits. Are
there any other possible reasons?


The missing 5% of "sure".


--
Ian White

"Ian White" wrote in message
...
KevCompton wrote:
Thanks for all the prompt replies.
I'm 95% sure that I had all the neutrals on the RCD protected neutral
bus bar as I had to swap them over to the non-RCD protected neutral bus
bar to get things working temporarily on the problem circuits. Are
there any other possible reasons?


The missing 5% of "sure".



I had to remove a power factor capacitor from a fluorescent lamp once. It
was isolated and most definitely only connected to live and neutral yet
virtually every time I switched it on it would take out the RCD.

I also had a computer which I learnt to leave permanently switched on and
only turn it on or off at the wall.

Equipment with mains filtering can be an issue. I've isolated capacitors
before now so there's no connection to earth.

Re CU tripping on most circuits:

The other thing not yet mentioned is your house wiring may have
connected neutrals between different circuits, or have loads that run
from live on one circuit to N on another.

Or there may be silmilar N/E issues.

I would remove all problem circuits from the CU, disconnecting all 3
L,N & E, and test with a multimeter to see what connects to what. Each
circuit should be entirely unconnected to each other one, except for
earths which can connect to other earths no problem. For lighting
circuits, switching all the unpowered lights on would enable the meter
to spot lights connected from one circuit's L to another one's N.

You just need to work through the possibilities, confirming or
eliminating one by one. Thats if you want to run them on an RCD. I dont
know which circuits they are, but it may be fine to not RCD some or all
of them, depends.


NT

Thanks for your reply, very useful. Earlier, I did a bit more checing
and it looks like different circuits are connected to each other. I
will do as you suggest and remove all wires on the problem circuits and
see what is connected to what. All the problem circuits are for the
sockets throughout the house.

You mentioned that the wiring may have loads that run from live on one
circuit to N on another. I think that may be my problem as continuity
between two L contacts on different circuits existed even though I had
disconnected them from the CU, leaving only the N and Earth still
connected. Why would this be done? Is it a normal thing to do in
certain conditions?

Thanks.

KevCompton wrote:

Thanks for your reply, very useful. Earlier, I did a bit more checing
and it looks like different circuits are connected to each other. I
will do as you suggest and remove all wires on the problem circuits and
see what is connected to what. All the problem circuits are for the
sockets throughout the house.

You mentioned that the wiring may have loads that run from live on one
circuit to N on another. I think that may be my problem as continuity
between two L contacts on different circuits existed even though I had
disconnected them from the CU, leaving only the N and Earth still
connected. Why would this be done? Is it a normal thing to do in
certain conditions?

Thanks.

Its quite common, if not best practice. If it were me I'd be asking
which of the problem circuits actually need to be on RCD. Either that
or you've got a bunch of tracing and rewiring to do.


NT

Slightly OT, but does anyone manufacture an "imbalance" current meter?

Christ, something Fred does not know the answer to and posted in thread
!!. Things are looking up.

Dave

wrote:

Some CUs come with a link wire between the neutral bus bars. You need to
remove that when using it as a split load unit.


Hmm, how do you get a neutral feed to it then ? do split CU's have
separate incomers/isolators per side ?

I thought it had a single isolator and separate RCD.

Does it need a dedicated tail per side in this case ?

I can't envisage it as I don't have a split load CU.

Live and neutral tails come into the incomer, thence go to the primary
neutral and phase bus bars. The RCD normally sits in the middle of the
CU and is fed both live and neutral from the primary bus bars (or
sometimes dedicared cables inside the CU). The RCD in turn feeds a
second live busbar for the protected MCBs and a separate neutral bus bar
for the protected circuits.



--
Cheers,

John.

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

John Rumm wrote:
zymurgy wrote:

Some CUs come with a link wire between the neutral bus bars. You need to
remove that when using it as a split load unit.


Hmm, how do you get a neutral feed to it then ? do split CU's have
separate incomers/isolators per side ?

I thought it had a single isolator and separate RCD.

Does it need a dedicated tail per side in this case ?

I can't envisage it as I don't have a split load CU.

Live and neutral tails come into the incomer, thence go to the primary
neutral and phase bus bars. The RCD normally sits in the middle of the
CU and is fed both live and neutral from the primary bus bars (or
sometimes dedicared cables inside the CU). The RCD in turn feeds a
second live busbar for the protected MCBs and a separate neutral bus bar
for the protected circuits.

Aha, thanks, got it.

So not shared neutral, isasmuchas the main neutral is fed via the RCD.
But with only one isolator.

Cheers

Paul.

KevCompton wrote:

Thanks for your reply, very useful. Earlier, I did a bit more checing
and it looks like different circuits are connected to each other. I
will do as you suggest and remove all wires on the problem circuits and
see what is connected to what. All the problem circuits are for the
sockets throughout the house.

You mentioned that the wiring may have loads that run from live on one
circuit to N on another. I think that may be my problem as continuity
between two L contacts on different circuits existed even though I had
disconnected them from the CU, leaving only the N and Earth still
connected. Why would this be done? Is it a normal thing to do in
certain conditions?

You need to disconnect neutral as well, otherwise you may be sing
continuity from live to live through a pair of loads and their common
neutral.

--
Cheers,

John.

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

wrote:

So not shared neutral, isasmuchas the main neutral is fed via the RCD.
But with only one isolator.

Main neutral is fed direct from the isolater. The Secondary neutral is
fed from the RCD (which is fed from the main neutral)

Same for the lives.

--
Cheers,

John.

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

In article .com,
KevCompton wrote:
I had four circuits attached to the RCD - Downstairs sockets, upstairs
sockets, garage sockets and the Shower. All of the circuits trip the
RCD apart from the shower. I have temporarily moved these problem
circuits over to the non-rcd side and they are all working fine.

Are you *absolutely* sure both neutrals on the rings go to the correct
neutral busbar? It would be unusual to have so many faults.

--
*Constipated People Don't Give A Crap*

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