First of all, it's ultimately possible that I've done something excessively
stupid to cause my problems (I say this so that no-one will rule out any of
the obvious suggestions).

I've just started rewiring my house today, I've ran a new set of tails to
my new consumer unit, and have another set of tails to my old consumer unit.
The new consumer unit is split load.

Just to test things out, I've wired a single socket to the new CU on the RCD
protected side.
If I plug anything what so ever into the socket I've wired in then the RCD
trips the moment the item is turned on.

I also had another consumer unit with RCD which I was going to use to
protect the external sockets. So I removed the RCD from that and used it to
replace the RCD in the installed consumer unit. The RCD's are exactly the
same model number. I get exactly the same response, immediate trip when a
device asks for power.

I rewired the socket over to the non RCD side of the consumer unit and it
works fine.

The socket is wired as a direct spur straight from the RCD rather than as a
loop (it's only for testing).

The consumer unit and the RCDs are Contactum.

Can anyone make any suggestions? I'm highly doubtful that I've been given
two duff RCDs but I can't think of anything else...

Help! Please?

Thanks

Seri

In article , Seri
wrote:
Just to test things out, I've wired a single socket to the new CU
on the RCD protected side.
If I plug anything what so ever into the socket I've wired in then
the RCD trips the moment the item is turned on.

Just to ask the obvious (not meaning to insult you) you have taken
the N from the socket through the RCD and not straight to a neutral
busbar ??

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

No insult what so ever, I know it's likely to be something silly like that.

Just checked and the neutral from the socket is wired into the shared
neutral bus bar, only the live is wired directly into the MCB.

I should say that this is my first time doing anything like this (as if that
probably wasn't patently obvious already).

Thanks anyway though

Seri

"Tony Bryer" wrote in message
...
| In article , Seri
| wrote:
| Just to test things out, I've wired a single socket to the new CU
| on the RCD protected side.
| If I plug anything what so ever into the socket I've wired in then
| the RCD trips the moment the item is turned on.
|
| Just to ask the obvious (not meaning to insult you) you have taken
| the N from the socket through the RCD and not straight to a neutral
| busbar ??
|
| --
| Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
| Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
|
|

On Sat, 03 Apr 2004 19:21:17 GMT, in uk.d-i-y "Seri"
strung together this:

Just to test things out, I've wired a single socket to the new CU on the RCD
protected side.
If I plug anything what so ever into the socket I've wired in then the RCD
trips the moment the item is turned on.

Have you got the neutral in the right busbar?

I also had another consumer unit with RCD which I was going to use to
protect the external sockets. So I removed the RCD from that and used it to
replace the RCD in the installed consumer unit. The RCD's are exactly the
same model number. I get exactly the same response, immediate trip when a
device asks for power.

Are you sure it's not the device you're plugging in that's at fault.
Most people tend to accuse RCD's of being faulty if they trip.

I rewired the socket over to the non RCD side of the consumer unit and it
works fine.

The socket is wired as a direct spur straight from the RCD rather than as a
loop (it's only for testing).

You mean hung off the bottom of thr RCD with no MCB?
--

SJW
A.C.S. Ltd.

On Sat, 03 Apr 2004 20:35:32 +0100, Tony Bryer
wrote:

In article , Seri
wrote:
Just to test things out, I've wired a single socket to the new CU
on the RCD protected side.
If I plug anything what so ever into the socket I've wired in then
the RCD trips the moment the item is turned on.

Just to ask the obvious (not meaning to insult you) you have taken
the N from the socket through the RCD and not straight to a neutral
busbar ??
..

..... and removed the link if there are two neutral bus bars......




..andy

To email, substitute .nospam with .gl

On Sat, 03 Apr 2004 19:42:54 GMT, in uk.d-i-y "Seri"
strung together this:

No insult what so ever, I know it's likely to be something silly like that.

Just checked and the neutral from the socket is wired into the shared
neutral bus bar, only the live is wired directly into the MCB.

Shared? You mean as in the one that the RCD feed, (top connections),
is taken from or the one that the load of the RCD connects to, i.e.
the one connected to the bottom of the RCD. It should be this one.

I should say that this is my first time doing anything like this (as if that
probably wasn't patently obvious already).

I've seen so called pros scratching their heads over this sort of
simple quandry!
--

SJW
A.C.S. Ltd.

Oh, remove the link? There are two neutral bus bars, the current flow of
neutral seems to be:

Neutral tail into top of master breaker
Neutral link from bottom of master breaker to first neutral bus bar
Neutral link from first bus bar into the top of the RCD
Neutral link from bottom of RCD into second neutral bus bar

After following all that through I noticed that my neutral from the socket
was into the first neutral bus bar and not the second.
I just shifted it over and voila, it all works... something so simple and I
feel so stupid.

Oh well, you live and learn.

Thanks for all your help, it was EXTREMELY appreciated as it was driving me
nuts and I couldn't see what was wrong.

A big thanks

Seri

"Andy Hall" wrote in message
...
| On Sat, 03 Apr 2004 20:35:32 +0100, Tony Bryer
| wrote:
|
| In article , Seri
| wrote:
| Just to test things out, I've wired a single socket to the new CU
| on the RCD protected side.
| If I plug anything what so ever into the socket I've wired in then
| the RCD trips the moment the item is turned on.
|
| Just to ask the obvious (not meaning to insult you) you have taken
| the N from the socket through the RCD and not straight to a neutral
| busbar ??
| .
|
| .... and removed the link if there are two neutral bus bars......
|
|
|
|
| .andy
|
| To email, substitute .nospam with .gl

In article , Seri
wrote:
After following all that through I noticed that my neutral from
the socket was into the first neutral bus bar and not the second.
I just shifted it over and voila, it all works... something so
simple and I feel so stupid.

Oh well, you live and learn.

How do think I knew g

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

On Sat, 03 Apr 2004 20:04:59 GMT, "Seri"
wrote:

Oh, remove the link? There are two neutral bus bars, the current flow of
neutral seems to be:

Neutral tail into top of master breaker
Neutral link from bottom of master breaker to first neutral bus bar
Neutral link from first bus bar into the top of the RCD
Neutral link from bottom of RCD into second neutral bus bar

After following all that through I noticed that my neutral from the socket
was into the first neutral bus bar and not the second.
I just shifted it over and voila, it all works... something so simple and I
feel so stupid.

Oh well, you live and learn.

Thanks for all your help, it was EXTREMELY appreciated as it was driving me
nuts and I couldn't see what was wrong.

A big thanks

Seri


It's very easily done. I've got a T-shirt.... :-)

..andy

To email, substitute .nospam with .gl

On

I've seen so called pros scratching their heads over this sort of simple
quandry!

Caught me out at least once, in front of a customer as well, DOH.

Dave

--
And you were born knowing all about ms windows....??

Seri wrote:

Oh, remove the link? There are two neutral bus bars, the current flow of
neutral seems to be:

Neutral tail into top of master breaker
Neutral link from bottom of master breaker to first neutral bus bar
Neutral link from first bus bar into the top of the RCD
Neutral link from bottom of RCD into second neutral bus bar

After following all that through I noticed that my neutral from the socket
was into the first neutral bus bar and not the second.
I just shifted it over and voila, it all works... something so simple and I
feel so stupid.

Oh well, you live and learn.


:-)

But you are a far better electrician for having got it wrong, aksed,
understood, and fixed it, than if you had blindly followed instructions
without ever woking out what where or why...



Thanks for all your help, it was EXTREMELY appreciated as it was driving me
nuts and I couldn't see what was wrong.

A big thanks

Seri

"Andy Hall" wrote in message
...
| On Sat, 03 Apr 2004 20:35:32 +0100, Tony Bryer
| wrote:
|
| In article , Seri
| wrote:
| Just to test things out, I've wired a single socket to the new CU
| on the RCD protected side.
| If I plug anything what so ever into the socket I've wired in then
| the RCD trips the moment the item is turned on.
|
| Just to ask the obvious (not meaning to insult you) you have taken
| the N from the socket through the RCD and not straight to a neutral
| busbar ??
| .
|
| .... and removed the link if there are two neutral bus bars......
|
|
|
|
| .andy
|
| To email, substitute .nospam with .gl

On Sun, 04 Apr 2004 08:46:04 +0100, in uk.d-i-y The Natural
Philosopher strung together this:

Seri wrote:

Oh, remove the link? There are two neutral bus bars, the current flow of
neutral seems to be:

Neutral tail into top of master breaker
Neutral link from bottom of master breaker to first neutral bus bar
Neutral link from first bus bar into the top of the RCD
Neutral link from bottom of RCD into second neutral bus bar

After following all that through I noticed that my neutral from the socket
was into the first neutral bus bar and not the second.
I just shifted it over and voila, it all works... something so simple and I
feel so stupid.

Oh well, you live and learn.


:-)

But you are a far better electrician for having got it wrong, aksed,
understood, and fixed it, than if you had blindly followed instructions
without ever woking out what where or why...

Quite right, I see too many droids mindlessly cobbling things together
without noticing what they're doing wrong or why they're even there.
I've just been to look at a job where someone else has done a test,
they appear to have missed most of the dangerous\dodgy bits and what
they've written down is either wrong or irrelevant\too vague to be any
use. Funnily enough they missed the bits they just put in incorrectly!
--

SJW
A.C.S. Ltd.

"Seri" wrote
| Neutral link from bottom of RCD into second neutral bus bar
| After following all that through I noticed that my neutral
| from the socket was into the first neutral bus bar and not
| the second.
| I just shifted it over and voila, it all works...

It is good practice to have the connections on the neutral and earth bars in
the same order as the circuits appear at the MCBs. If you get into that
habit you're less likely to put a neutral on the wrong bar.

Owain

"Owain" wrote in message
...
| "Seri" wrote
| | Neutral link from bottom of RCD into second neutral bus bar
| | After following all that through I noticed that my neutral
| | from the socket was into the first neutral bus bar and not
| | the second.
| | I just shifted it over and voila, it all works...
|
| It is good practice to have the connections on the neutral and earth bars
in
| the same order as the circuits appear at the MCBs. If you get into that
| habit you're less likely to put a neutral on the wrong bar.
|
| Owain
|

Funilly enough, it was doing precisely this that caused my problems in the
first place!

It's a split load consumer unit but I had to manually split the main bus
bar, because I wanted most circuits to be RCD protected I split it so that
MCBs 1-5 were non RCD protected and 6-12 were.

The ring I wired in was for MCB 6 (RCD protected).

The Neutral bar for the non RCD side was for MCBs 1-6.

Hence how I made my mistake... Wired the new circuit into MCB 6, Earth Bus
Bar Point 6, Neutral Bus Bar Point 6...

Does mean now that I'll end up with some empty points on the non RCD Neutral
Bus and some points that are doubled up on the RCD protected side now...

Still, at least it's all working, I completed the ring and then used it to
plug the power tools into to start the rest of the work in that room, no
trips and a clean mains feed at last!

Thanks again for all your help folks.

Seri

In message ,
"Seri" wrote:

"Owain" wrote in message
...
| "Seri" wrote
| | Neutral link from bottom of RCD into second neutral bus bar
| | After following all that through I noticed that my neutral
| | from the socket was into the first neutral bus bar and not
| | the second.
| | I just shifted it over and voila, it all works...
|
| It is good practice to have the connections on the neutral and earth bars
in
| the same order as the circuits appear at the MCBs. If you get into that
| habit you're less likely to put a neutral on the wrong bar.
|
| Owain
|

Funilly enough, it was doing precisely this that caused my problems in the
first place!


Bloomin' Volexes that I've been using are even more confusing. There is
no numbering on the MCBs, but the (already split) neutral is numbered
(IIRC) 1 to 8 (L to R) non-RCD, and 8 to 1 (L to R) on the RCD side
(the live busbar is not split so that you have a (little) flexibility).
The Earth, of course, is one busbar numbered 1 to 12.

So MCB 1 is non-RCD protected and the circuit connects to neutral 1 and
earth 1.

The MCB furthest right is RCD protected. It should probably be numbered
12, but it connects to neutral 1 (on the RCD bar) and earth 12.

Or something like that...

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Play electronic games? You have too much time on your hands.

Bloomin' Volexes that I've been using are even more confusing. There is
no numbering on the MCBs, but the (already split) neutral is numbered
(IIRC) 1 to 8 (L to R) non-RCD, and 8 to 1 (L to R) on the RCD side

I don't get these issues. RCBOs rule! Easier to wire up, too, as the entire
cable goes into the top of them, without touching the neutral bus bar at all
(which is not split), so no need to work out how much longer the neutral
needs to be than the live and leads to neater internal wiring.

Christian.

In message ,
"Christian McArdle" wrote:

Martin Angove wrote:

Bloomin' Volexes that I've been using are even more confusing. There is
no numbering on the MCBs, but the (already split) neutral is numbered
(IIRC) 1 to 8 (L to R) non-RCD, and 8 to 1 (L to R) on the RCD side

I don't get these issues. RCBOs rule!

I'm sorry, but if it's a choice between a Screwfix populated split-load
Volex (RCD and 10 MCBs) for £60, or similarly populated Wylex for £75 and
£250 (yes, TWO HUNDRED AND FIFTY POUNDS) or more for half a dozen RCBOs,
an unpopulated CU and a few MCBs then very few of my clients will see the
logic of the latter, especially if the RCBOs are of the two-module variety
and so for the same number of circuits I need to install more or bigger CUs.

Even in my own installation I've gone for a standard split-load with
just one RCBO feeding a radial to the utility room / outside socket.

If money were no object then individual RCBOs make sense, if only from a
discrimination point of view, but in the real world the difference
between £60 and £250 is a huge percentage of the parts cost of even a
complete rewire in most houses. I have recently finished a complete
rewire where the parts cost was about £400 - three rings, two radials,
two lights, cooker, shower, immersion, data, all new parts. They had a £60
CU, swapping that for a £250 one would have increased the parts cost by
some 50%

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... "Bother", said Pooh, as he failed the dope test.

I have recently finished a complete rewire where the parts cost was
about £400 - three rings, two radials, two lights, cooker, shower,
immersion, data, all new parts. They had a £60 CU, swapping that
for a £250 one would have increased the parts cost by some 50%

As RCBOs cost around 40 quid, I'm interested to know why you need 6 RCBOs.
I've got 3 on mine, and I'm not even using the third one yet. It is reserved
for exterior electrics. The other two do ring circuits. I have 2 radial
socket circuits too, for integrated appliances, but these are MCB only as
the sockets are not accessible. Lighting, immersion etc. are not protected.

The first RCBO comes for free, as you would have needed an RCD anyway.
Subsequent ones come for 34 quid effective, as the MCB would have cost 6.
Another alternative is to split load, but use an RCBO for outside electrics,
where the chances of a nuisance trip are high. So even if you protect 3
rings and the shower, you're talking about 100 quid more than a split load,
like for like.

Christian.

In article ,
"Christian McArdle" writes:
I have recently finished a complete rewire where the parts cost was
about £400 - three rings, two radials, two lights, cooker, shower,
immersion, data, all new parts. They had a £60 CU, swapping that
for a £250 one would have increased the parts cost by some 50%

As RCBOs cost around 40 quid [...]

Not from an electrical wholesaler...

--
Andrew Gabriel

As RCBOs cost around 40 quid [...]

Not from an electrical wholesaler...

Out of interest, where can you get them cheaper? The only sub 40 quid price
I got was 30 quid from screwfix, but these were bizarrely Type C, so as
useful as a chocolate teapot.

Christian.

In article ,
"Christian McArdle" writes:
As RCBOs cost around 40 quid [...]

Not from an electrical wholesaler...

Out of interest, where can you get them cheaper? The only sub 40 quid price
I got was 30 quid from screwfix, but these were bizarrely Type C, so as
useful as a chocolate teapot.

I've bought from WF and Edmonson (ERD). I don't remember the exact
price, but I'm pretty sure MK single way RCBO's were under £30
(particularly from my local WF which is an MK specialist/stockist).

Type C is unlikely to be a problem, particularly with RCD protection,
although Type B is easy enough to come by and is what I would use on
a domestic ring circuit.

--
Andrew Gabriel

"Christian McArdle" wrote in message
et...
As RCBOs cost around 40 quid, I'm interested to know why you need 6
RCBOs.
I've got 3 on mine, and I'm not even using the third one yet. It is
reserved
for exterior electrics. The other two do ring circuits. I have 2
radial
socket circuits too, for integrated appliances, but these are MCB only
as
the sockets are not accessible. Lighting, immersion etc. are not
protected.

The first RCBO comes for free, as you would have needed an RCD anyway.
Subsequent ones come for 34 quid effective, as the MCB would have cost
6.
Another alternative is to split load, but use an RCBO for outside
electrics,
where the chances of a nuisance trip are high. So even if you protect
3
rings and the shower, you're talking about 100 quid more than a split
load,
like for like.

My CU is a Memera 2000 and apparently I can add an RCD pod to the
existing MCBs which will upgrade them to RCBOs - is it worthwhle to do
this or should I just change the MCB for an RCBO, where I want RCD
protection? I don't think there's much of a price difference.

Neil

In article ,
"Neil Jones" writes:

My CU is a Memera 2000 and apparently I can add an RCD pod to the
existing MCBs which will upgrade them to RCBOs - is it worthwhle to do
this or should I just change the MCB for an RCBO, where I want RCD
protection? I don't think there's much of a price difference.

You will find that the MEM RCBO you buy is simply an MCB and
RCBO pod clipped together. If they do one in exactly the rating
combination you want (not all variations are available preassembled),
then you might as well go for it. Note that you are not supposed to
disassemble the MCB and RCBO from each other once assembled, even if
it is one you assembled yourself. (I've been tempted once or twice,
but in the end never actually needed to.)

Also be careful as the Memshield 2 commercial range works the same way
but they seem to have different MCB part numbers, so I would assume
they aren't interchangable unless someone can confirm they are.

--
Andrew Gabriel

On 7 Apr 2004 14:35:33 GMT, in uk.d-i-y
(Andrew Gabriel) strung together this:

In article ,
"Neil Jones" writes:

My CU is a Memera 2000 and apparently I can add an RCD pod to the
existing MCBs which will upgrade them to RCBOs - is it worthwhle to do
this or should I just change the MCB for an RCBO, where I want RCD
protection? I don't think there's much of a price difference.

You will find that the MEM RCBO you buy is simply an MCB and
RCBO pod clipped together. If they do one in exactly the rating
combination you want (not all variations are available preassembled),
then you might as well go for it. Note that you are not supposed to
disassemble the MCB and RCBO from each other once assembled, even if
it is one you assembled yourself. (I've been tempted once or twice,
but in the end never actually needed to.)

Also be careful as the Memshield 2 commercial range works the same way
but they seem to have different MCB part numbers, so I would assume
they aren't interchangable unless someone can confirm they are.

They are interchangable, it's the short circuit capacity that's the
only difference AFAIK, 6kA for the Memera 2000 and 10kA for the
Memshield 2.
--

SJW
A.C.S. Ltd.

In article ,
(Lurch) writes:
On 7 Apr 2004 14:35:33 GMT, in uk.d-i-y
(Andrew Gabriel) strung together this:

Also be careful as the Memshield 2 commercial range works the same way
but they seem to have different MCB part numbers, so I would assume
they aren't interchangable unless someone can confirm they are.

They are interchangable, it's the short circuit capacity that's the
only difference AFAIK, 6kA for the Memera 2000 and 10kA for the
Memshield 2.

Ah that makes sense, and indeed the Memshield 2 ones I have here
are marked 10kA.

--
Andrew Gabriel

In message ,
"Christian McArdle" wrote:

I have recently finished a complete rewire where the parts cost was
about £400 - three rings, two radials, two lights, cooker, shower,
immersion, data, all new parts. They had a £60 CU, swapping that
for a £250 one would have increased the parts cost by some 50%

As RCBOs cost around 40 quid, I'm interested to know why you need 6 RCBOs.
I've got 3 on mine, and I'm not even using the third one yet. It is reserved
for exterior electrics. The other two do ring circuits. I have 2 radial
socket circuits too, for integrated appliances, but these are MCB only as
the sockets are not accessible. Lighting, immersion etc. are not protected.


Well I suppose it depends on arrangements, and whether you think all
sockets circuits should be RCD protected. The installation I was
thinking of actually had five RCD circuits - three rings (upstairs,
downstairs, kitchen), one 20A radial (office in attic) and an electric
shower. It had five non-RCD circuits, lights up and down, cooker,
immersion and fridge/freezer. Actually the f/f socket was very
accessible and so I gave it an RCD faceplate.

The first RCBO comes for free, as you would have needed an RCD anyway.
Subsequent ones come for 34 quid effective, as the MCB would have cost 6.
Another alternative is to split load, but use an RCBO for outside electrics,
where the chances of a nuisance trip are high. So even if you protect 3
rings and the shower, you're talking about 100 quid more than a split load,
like for like.

Well, not quite. Leaving aside Andrew's claim to have found RCBOs under
30 quid I am going to quibble with your figures. I've had a tiring day
and need something daft to think about :-)

I have found Screwfix to be consistently cheapest for most things, and
they have a few more things in cat 74 which fell through the door today.
Let's do some comparisons for a ten-circuit installation:

Split load Volex kit, 12-way board, 10 MCBs - £60.
The same board without MCBs, but including split kit - £49 (in cat 73 it
is £60)

In other words, the MCBs are free in cat 73, but £1.10 each in cat 74.
To buy them individually they are £3.79.

Split load Wylex kit, 12-way board, 10 MCBs - £75.
The same board without MCBs, but including split kit - £55

In other words, the MCBs are effectively £2 each (£4.69 in the
catalogue).

This, of course, ignores the possibility that you would need to swap one
of the supplied MCBs for a differently rated one.

Now let's do it using RCBOs. Unfortunately, Volex RCBOs although £10
cheaper than Wylex ones are two modules wide so for the same number of
circuits we need:

1 Service connector block - £6.70
2 extra sets of meter tails - £4.90
2 11-way Volex non split boards - £38
5 Volex RCBOs (almost fill one board) - £150
5 Volex MCBs (leave half the other board empty) - £19

Grand total: £218.60

The Wylex solution is simpler as their RCBOs are 1 module wide:

1 11-way Wylex consumer unit - £26
5 Wylex RCBOs - £200
5 Wylex MCBs - £23.50

Grand total: £249.50

So, far from being £100 different, the Volex RCBO solution is £158.60
more expensive than the simple split-load kit, and the Wylex is £174.50
more expensive (all bar a few pennies - I did some rounding of 0.99ps to
£1s).

All round I think that usually the most appropriate solution will be a
simple split load board, possibly with extra RCBO / local RCD protection
of one or two circuits, which is what you suggested in your last
sentence. This is what I am doing in my own house: three rings, one
radial. The radial isn't on the common RCD, it's on an RCBO and feeds
the utility room and an outside socket.

Thanks for letting me do that, I feel much more relaxed now :-)

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Happiness is a conscious choice, not an automatic response.

On Thu, 08 Apr 2004 21:07:27 +0100, in uk.d-i-y Martin Angove
strung together this:

Well, not quite. Leaving aside Andrew's claim to have found RCBOs under
30 quid I am going to quibble with your figures. I've had a tiring day
and need something daft to think about :-)

[snip calculations]

But you could, on a new installation, have one RCBO protected circuit
powering a collection of outside sockets at roughly each corner of the
building, and that would be all that was needed. How much difference
would that be then?
--

SJW
A.C.S. Ltd.

In message ,
(Lurch) wrote:

On Thu, 08 Apr 2004 21:07:27 +0100, in uk.d-i-y Martin Angove
strung together this:

Well, not quite. Leaving aside Andrew's claim to have found RCBOs under
30 quid I am going to quibble with your figures. I've had a tiring day
and need something daft to think about :-)

[snip calculations]

But you could, on a new installation, have one RCBO protected circuit
powering a collection of outside sockets at roughly each corner of the
building, and that would be all that was needed. How much difference
would that be then?

Well, that is nearly the same as I have suggested at the end of all that
twaddle. The way I did it was to buy a Volex split kit for £60 and add
a Volex RCBO for £30 - so total cost £90. It's not just outside sockets
which need RCD protection remember, so it's not a simple case of buying
a non-RCD board + MCBs for £not much and just using a single RCBO :-)

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... If it's not broke, let me take a crack at it.

On Thu, 08 Apr 2004 22:23:59 +0100, in uk.d-i-y Martin Angove
strung together this:

In message ,
(Lurch) wrote:

On Thu, 08 Apr 2004 21:07:27 +0100, in uk.d-i-y Martin Angove
strung together this:

Well, not quite. Leaving aside Andrew's claim to have found RCBOs under
30 quid I am going to quibble with your figures. I've had a tiring day
and need something daft to think about :-)

[snip calculations]

But you could, on a new installation, have one RCBO protected circuit
powering a collection of outside sockets at roughly each corner of the
building, and that would be all that was needed. How much difference
would that be then?

Well, that is nearly the same as I have suggested at the end of all that
twaddle. The way I did it was to buy a Volex split kit for £60 and add
a Volex RCBO for £30 - so total cost £90. It's not just outside sockets
which need RCD protection remember, so it's not a simple case of buying
a non-RCD board + MCBs for £not much and just using a single RCBO :-)

In *most* installations then. RCD protection is required for portable
equipment used outdoors, and occasionally other singular items inside
which can usually be covered by an RCD spur. As with most things on
here the actual end result after OT tangents is pretty much every
installation differs, so there is no hard and fast rule!
One thing I just noticed you missed from the original calculations was
the need for a DP switch and enclosure to be able to isolate both
boards from one point. So another £15 or so.
--

SJW
A.C.S. Ltd.

In message ,
(Lurch) wrote:

On Thu, 08 Apr 2004 22:23:59 +0100, in uk.d-i-y Martin Angove
strung together this:

The way I did it was to buy a Volex split kit for £60 and add a Volex
RCBO for £30 - so total cost £90. It's not just outside sockets which
need RCD protection remember, so it's not a simple case of buying a
non-RCD board + MCBs for £not much and just using a single RCBO :-)

In *most* installations then. RCD protection is required for portable
equipment used outdoors, and occasionally other singular items inside
which can usually be covered by an RCD spur. As with most things on
here the actual end result after OT tangents is pretty much every
installation differs, so there is no hard and fast rule!

Absolutely. I was simply taking issue with the assertion that n RBCOs
is always "better" than n MCBs protected by a common RCD. I was also
pointing out that in all practical circumstances (i.e. more than one
circuit on an RCD) using a common RCD will work out a lot cheaper. When
you're talking about £40 for each extra RCBO, that's 10% of the total
parts cost!

The fact is that in most installations it makes sense to have more
circuits RCD protected than is the bare minimum, and the inginuity of the
house owner is to be respected. For example, there is not normally a
requirement for upstairs sockets to be RCD protected, but the house I was
using as an example was built on a hill and, despite the presence of an
outdoor socket near the back door I consider it highly possible that at
some stage someone will string an extension lead out of the back bedroom
window :-)

One thing I just noticed you missed from the original calculations was
the need for a DP switch and enclosure to be able to isolate both
boards from one point. So another £15 or so.

Hmmm... could turn into quite a mess of 25mmsq cables ;-)

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... A trampoline is for cunning stunts, a truncheon for apprehending criminals

On Fri, 09 Apr 2004 18:15:30 +0100, in uk.d-i-y Martin Angove
strung together this:

One thing I just noticed you missed from the original calculations was
the need for a DP switch and enclosure to be able to isolate both
boards from one point. So another £15 or so.

Hmmm... could turn into quite a mess of 25mmsq cables ;-)

Could do. Depending on the actual installation layout. Where possible
I run a piece of 2x2 or 3x3 PVC trunking along the top or side of the
two CUs and also across the top of the henley block and switch. All
the cables are then hidden as they enter and leave the various
switches, connections and CUs. Very tidy looking, it's exactly how
I've got my installation setup at home.
--

SJW
A.C.S. Ltd.