Hi,

about to add new circuits and need extra circuit breakers.

Screwfix lists type B and C (what happened to Type A)?

Both are shown as ISO rail fitting.

So:

will almost any circuit breaker fit any consumer unit (CU was replaced six
years ago) because they are an ISO standard fitting, or is it a case of
loads of different fittings?

Consumer unit is Siemens Stratus 200
Breakers are all marked 5sx21
Ratings are B32 or B6 (so presumably a 'B' type breaker).

See http://www.siemens-industry.co.uk/ne...rel.asp?ID=118 - apparently
they are miniature circuit breakers.

See http://www.siemens-industry.co.uk/di...n/alpha200.asp - RCCB,
switch, or split load.

Now I am more confused instead of less.

http://www.chelsworth-lodge.nildram....s/DSC00113.JPG
http://www.chelsworth-lodge.nildram....s/DSC00114.JPG


These show my incoming power and the consumer unit.

I have (it looks like) two switches for incoming power (LHS), plus an RCCD
(RHS).

How do I tell if this is all on the RCCD, or if the lighting (LHS) is
switched - which I would presume is a split load (from reading the FAQ).
It looks like a split load setup.
Is the cut in the busbar easily visible?

This brings me on to connecting in the new wiring (13 amp ring main and
immersion heater on a direct circuit).

As I seem to have two switches on the main switch, I presume one is for the
lighting side, and one for the power via the RCCD.
So I presume that I could keep the lighting running with the power side off
whilst I connect in the new cables.

(1) I turn off the main switch on the consumer unit - darkness reigns.
(2) Remove the cover
(3) Turn on the lighting side again so I can see what I am doing without
using a torch.
(4) Pull the RCCB for extra safety?
(5) Connect in the new wires
(6) Add the new mini-RCBs
(7) Power up power side (RCCD back in) with cover off and extreme care then
test the new circuits.
(8) Power everything off again and re-install the cover.
(9) Power up and celebrate.
(10) Go round resetting all the clocks, CH timers etc.

Any advice much appreciated - main issue is 'do the type B RCDs from
Screwfix fit these units - answer please in time to place the order today
:-)

TIA
Dave R

P.S.
Included the picture of the power side because I seem to have three blocks
on the inbound side - one is used for the meter and two spares.
I know there used to be storage heaters - unused sockets in the wall and a
very nasty charred CU in the garage before we had all this replaced - so
that would explain one extra service, but what was the other one for?
Is it usual to have the incoming service split into 3?
A relic of the old multiple fuse box setup?
I note there is no isolating switch between power in and the CU - would this
be a good idea or is the switch on the input side of the CU adequate?

Screwfix lists type B and C (what happened to Type A)?

Always use Type B, unless you have a specific reason to use a lower
protection rating (you don't!). There is no Type A, although I'd like to buy
some if they made one. They'd be very useful for large pure resistive
circuits, such as cookers.

I have (it looks like) two switches for incoming power (LHS), plus an RCCD
(RHS).

You'll see that the switch on the left has the two handles connected
together. This is because it is a double pole switch that switches both the
Neutral and the Live at the same time. It should cut power to the entire
consumer unit.

So I presume that I could keep the lighting running with the power side off
whilst I connect in the new cables.

I wouldn't. There will be live busbars in the consumer unit, protected only
by your incoming service fuse. I wouldn't want to short that out by dropping
my screwdriver. Turn off the main isolator (left hand switch) before doing
any wiring up.

will almost any circuit breaker fit any consumer unit (CU was replaced six
years ago) because they are an ISO standard fitting, or is it a case of
loads of different fittings?

Most makes will fit most boards. However, many will claim that you should
not do so, or that it will invalidate the guarantee. If you are worried,
then buy Siemens ones, if you can find them.

Is it usual to have the incoming service split into 3?

Yes. Electricity is generated and transported around the country in three
phases, 120 degrees apart. Large industrial motors use all 3 phases as they
can maintain constant power throughout the mains cycle. A standard domestic
electricity supply uses one of the 3 phases selected at random by the
electricity company, often fused at 100A for a modern installation, although
older ones may be 40A or 60A.

With electrical heating installations, such as storage heaters, you would
typically have a 2 or 3 phase supply as they draw too much power for a
standard domestic cutout. So your guess is probably correct that you did
once have a 3 phase supply. It was probably all removed when all the Economy
7 gubbins were removed and a single phase meter installed.

BTW, I'm slightly worried by some of your questions. You might want to
consider doing the main wiring up of the circuits and then get an
electrician in to test and make the final connections. You need some very
expensive test gear to do the circuit testing, not a 2.99 multimeter from
Maplins.

Christian.

"Christian McArdle" wrote in message
t...
snip
Most makes will fit most boards. However, many will claim that you should
not do so, or that it will invalidate the guarantee. If you are worried,
then buy Siemens ones, if you can find them.
**
I would if I could - it is the obvious safe solution.
However I can't seem to Google any suppliers.
Hence the question about universal fit
**
snip
BTW, I'm slightly worried by some of your questions. You might want to
consider doing the main wiring up of the circuits and then get an
electrician in to test and make the final connections. You need some very
expensive test gear to do the circuit testing, not a 2.99 multimeter from
Maplins.

Christian.

Thanks for the prompt response and good advice.
I have read the FAQ on testing a circuit - it says "You need a low
resistance ohm-meter with good resolution, say a range of 0 - 2 ohms with
divisions of 0.05 ohm. ".
Is this the really expensive test gear you mention?
If so, how much is 'very expensive' likely to be?

I am pretty confident that I can safely connect to a consumer unit - I have
done so several times in the past just not to one of these new fangled fancy
gizmos you young fellas seem to favour these days :-)

On reflection, as you suggest, keeping the lighting power on may not be the
greatest move - I was lured by the joys of electric light instead of a torch
:-)

If the test gear is unreasonably expensive I will chat to our local
electrician about commissioning the wiring.

Cheers
Dave R

If the test gear is unreasonably expensive I will chat to our local
electrician about commissioning the wiring.

To do it properly, you need a continuity tester capable of 200mA test
current (NOT a multimeter!), an insulation resistance checker capable of
500VDC, an earth loop impedence tester and an RCD tester. You can get the
whole lot for around 600 quid. Of course, most people don't seem to do it
properly.

The most important part is the continuity/insulation resistance tester,
which are normally on the same instrument. The cheapest of these are around
200 quid new. I got mine for 35 quid on eBay from someone who thought it was
a broken electronic thermometer. He admitted afterwards that he sold it
because it gave him a nasty electric shock when he was playing with it.
(500V does that!)

Christian.

On Mon, 3 Nov 2003 13:43:04 -0000, "David W.E. Roberts"
wrote:



On reflection, as you suggest, keeping the lighting power on may not be the
greatest move - I was lured by the joys of electric light instead of a torch
:-)


I've implemented a fairly simple solution to deal with this, which is
a small maintained emergency light.

These can be obtained from electrical wholesalers quite inexpensively
and are a fluorescent tube fitting with electronics and a battery
backup which lasts 3 hours. I installed a small 8W one immediately
above and in front of the consumer unit in a cupboard. It is
charged from a lighting circuit and is switched on normally when the
door is opened.

However, it will also come on, powered by battery, if the power fails
or is deliberately turned off to do work.

This is much better than playing around with torches in confined
spaces or leaving the power on and working on the CU live.
I've seen the melted remains of a fairly substantial screwdriver in
the bottom of a CU after it managed a short between the bus bar and
the metal case..........




..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Mon, 3 Nov 2003 13:43:04 -0000, "David W.E. Roberts"
wrote:



On reflection, as you suggest, keeping the lighting power on may not be
the
greatest move - I was lured by the joys of electric light instead of a
torch
:-)


I've implemented a fairly simple solution to deal with this, which is
a small maintained emergency light.

These can be obtained from electrical wholesalers quite inexpensively
and are a fluorescent tube fitting with electronics and a battery
backup which lasts 3 hours. I installed a small 8W one immediately
above and in front of the consumer unit in a cupboard. It is
charged from a lighting circuit and is switched on normally when the
door is opened.

However, it will also come on, powered by battery, if the power fails
or is deliberately turned off to do work.

This is much better than playing around with torches in confined
spaces or leaving the power on and working on the CU live.
I've seen the melted remains of a fairly substantial screwdriver in
the bottom of a CU after it managed a short between the bus bar and
the metal case..........

I have a battery light on the wall by the CU - not as elegant as your
solution but better than nothing (as long as it is checked regularly).

Just looked on Screwfix and they do one for £21 - so I've added this to my
order.

Thanks
Dave R

I would if I could - it is the obvious safe solution.
However I can't seem to Google any suppliers.
Hence the question about universal fit

The following are claimed to stock Siemens:

http://www.rexelsenate.co.uk/
http://www.neweyandeyre.co.uk/
http://www.ac-electrical.co.uk/

Some of the websites are pretty useless, though.

Christian.

All done now.

"David W.E. Roberts" wrote in message
...
Hi,

about to add new circuits and need extra circuit breakers.

snip
As I seem to have two switches on the main switch, I presume one is for
the
lighting side, and one for the power via the RCCD.
So I presume that I could keep the lighting running with the power side
off
whilst I connect in the new cables.

*** ..errr...yes - having taken the front off there is no way I would work
on it with the power up! ***

snip
I note there is no isolating switch between power in and the CU - would
this
be a good idea or is the switch on the input side of the CU adequate?

*** Yep - switch on the input side seems fine to isolate everything ****

The scariest thing was the huge black spider which had taken up residence
inside the CU which made me jump more than a jolt from the mains :-)

The 'pattern' RCB fitted well, but squeezed the blanking plates up a
fraction.

Thanks to everyone for helpful advice.

Cheers
Dave R

The scariest thing was the huge black spider which had taken up residence
inside the CU which made me jump more than a jolt from the mains :-)

So you've never touched the mains before then?

Mungo

"Mungo Henning" wrote in message
...

The scariest thing was the huge black spider which had taken up
residence
inside the CU which made me jump more than a jolt from the mains :-)

So you've never touched the mains before then?

Mungo

When hooking my finger round a plug, touching banjaxed wiring etc. I get a
serious quiver up my arm (no archery jokes please).
This doesn't make me jump much at all - just quiver gently.

Large black spiders, however, do produce large involuntary muscle
contractions and distinct motion in an away direction.

:-)