Hi All,

Just moved into a 50's ex council house and need some advice/pointers.

Appear to have a modern CU (Siemens) with following MCBs (siemens 5sx2)
etc
(from left to right)

6A lighting circuit, 100A Switch, 20A (Unknown), 32A Sockets, 32A
Sockets, RCD
(ie whole house is rcd protected)

(Main and supplementary Earth bonding looks OK - TN-S)

ALL the sockets in the house seem to be fed via BOTH 32A MCB's.

ie to isolate any socket in the house requires that both 32A MCB be in
the OFF
position.

This just doesn't seem right to me....

"garion" wrote in message
oups.com...
Hi All,

Just moved into a 50's ex council house and need some
advice/pointers.

Appear to have a modern CU (Siemens) with following MCBs (siemens
5sx2)
etc
(from left to right)

6A lighting circuit, 100A Switch, 20A (Unknown), 32A Sockets, 32A
Sockets, RCD
(ie whole house is rcd protected)

(Main and supplementary Earth bonding looks OK - TN-S)

ALL the sockets in the house seem to be fed via BOTH 32A MCB's.

ie to isolate any socket in the house requires that both 32A MCB be
in
the OFF
position.

This just doesn't seem right to me....


Sounds like someone has confused the start and finish of the upstairs
and downstairs rings thus making a sort of figure of eight so I bet
you'll find that one mcb has and upstairs 'start' and a downstairs
'finish' wheras the other mcb has an upstairs 'finish' and a
downstairs 'start'. My house was like that when I bought it -
relatively easy error for someone to make but potentially lethal.

(Bet the 20a is an immersion heater or maybe cooker or shower)

AWEM

"garion" wrote in message
oups.com...
Hi All,

Just moved into a 50's ex council house and need some advice/pointers.

Appear to have a modern CU (Siemens) with following MCBs (siemens 5sx2)
etc
(from left to right)

6A lighting circuit, 100A Switch, 20A (Unknown), 32A Sockets, 32A
Sockets, RCD
(ie whole house is rcd protected)

(Main and supplementary Earth bonding looks OK - TN-S)

ALL the sockets in the house seem to be fed via BOTH 32A MCB's.

ie to isolate any socket in the house requires that both 32A MCB be in
the OFF
position.

This just doesn't seem right to me....


Is there just one cable running from each MCB? If so, suggests that each end
of a single ring has been wired into separate ways. Quite wrong, as you
imply.

If there are two cables from each MCB that would suggest two separate ring
circuits but wrongly wired at the CU so that each end of each goes into
separate ways. Again quite wrong. As I'm sure you know a ring has and must
have only one circuit protector.

garion wrote:

Appear to have a modern CU (Siemens) with following MCBs (siemens 5sx2)
etc (from left to right)

6A lighting circuit, 100A Switch, 20A (Unknown), 32A Sockets, 32A
Sockets, RCD (ie whole house is rcd protected)

That's a very bizarre layout - main switch in between two MCBs, RCD at
the other end. Have you looked inside to see how it's wired? Where do
the tails go in? A photo (with cover removed) would probably be quite
interesting, if you can put one up on the Web somewhere. Are you sure
everything goes through the RCD?

ALL the sockets in the house seem to be fed via BOTH 32A MCB's.

At one time, when ring circuits were still a novelty, this was a fairly
common practice. Two 15 A radials were converted into a ring, with no
change to the fusing. Whether this was ever sanctioned by the IEE regs
committee I don't know, but it did go on.

This just doesn't seem right to me....

Too right! Sounds to me like an electrician from the Wild West may have
visited and has replaced an old fusebox with an modern CU, attempting to
replicate the previous layout as closely as possible, throwing in an RCD
for good luck. I don't suppose for a moment that you got an Electrical
Installation Certificate?

--
Andy

"garion" wrote in message
oups.com...
Hi All,

Just moved into a 50's ex council house and need some advice/pointers.

Appear to have a modern CU (Siemens) with following MCBs (siemens 5sx2)
etc
(from left to right)

6A lighting circuit, 100A Switch, 20A (Unknown), 32A Sockets, 32A
Sockets, RCD
(ie whole house is rcd protected)

(Main and supplementary Earth bonding looks OK - TN-S)

ALL the sockets in the house seem to be fed via BOTH 32A MCB's.

ie to isolate any socket in the house requires that both 32A MCB be in
the OFF
position.

This just doesn't seem right to me....


What is the cable core sizes from each MCB? How do you know the ccts are not
radials in 4sqmm?

Jaymack

"garion" wrote in message
oups.com...
Hi All,

Just moved into a 50's ex council house and need some advice/pointers.

Appear to have a modern CU (Siemens) with following MCBs (siemens 5sx2)
etc
(from left to right)

6A lighting circuit, 100A Switch, 20A (Unknown), 32A Sockets, 32A
Sockets, RCD
(ie whole house is rcd protected)

(Main and supplementary Earth bonding looks OK - TN-S)

ALL the sockets in the house seem to be fed via BOTH 32A MCB's.

ie to isolate any socket in the house requires that both 32A MCB be in
the OFF
position.

This just doesn't seem right to me....

Sorry, just reread the posting, seems that you have a miswired ring if the
two MCB's are required to isolate.
I would recommend a PIR be done on your installation..
Jaymack

Andy Wade wrote:
garion wrote:

ALL the sockets in the house seem to be fed via BOTH 32A MCB's.

At one time, when ring circuits were still a novelty, this was a fairly
common practice. Two 15 A radials were converted into a ring, with no
change to the fusing. Whether this was ever sanctioned by the IEE regs
committee I don't know, but it did go on.

This just doesn't seem right to me....

Too right! Sounds to me like an electrician from the Wild West may have
visited and has replaced an old fusebox with an modern CU, attempting to
replicate the previous layout as closely as possible, throwing in an RCD
for good luck. I don't suppose for a moment that you got an Electrical
Installation Certificate?

A 1950s house is the right age too. Is the wiring original rubber by
any chance?

Yes it needs sorting, a 64A protected ring isnt a good idea. Simply
putting the 2 tails into one 32A mcb is the simplest solution, but I'd
want to look around and see if the ring was ok too, as someone has made
a significant screwup there.


NT

Andy Wade wrote:
That's a very bizarre layout - main switch in between two MCBs, RCD at
the other end. Have you looked inside to see how it's wired? Where do
the tails go in? A photo (with cover removed) would probably be quite
interesting, if you can put one up on the Web somewhere. Are you sure
everything goes through the RCD?


Havent even attempted to remove the cover yet.
(Dont know if I really want too!!)

Certainly seems to. If you turn the 100a switch off only lights go out,

if you turn RCD off everything goes off.

(Internet access bit difficult at the moment as still need to
arrange ISP at home)

Electrical Installation Certificate??? hmmm

Exposed the wiring to the CU last night, looks like standard T&E,
except lighting circuits which is single core live, and Live+E cable.

4 x 2.5mm2 cables (one runs about 1m to switch for outside light) other
3 disappear into
ceiling.

Multiple live+e

1 x 4mm2 Not connected into CU.

Will have to investigate further I think....

garion wrote:

Havent even attempted to remove the cover yet.
(Dont know if I really want too!!)

Certainly seems to. If you turn the 100a switch off only lights go out,

if you turn RCD off everything goes off.

Oh dear - this is not a regular job...

[...]

Will have to investigate further I think....

Yes. If you don't feel confident to sort this by DIY, do as John McLean
said and get an electrician in to PIR the whole premises. I would not
be surprised to learn that there's a whole bunch of other horrors just
waiting to be discovered.

--
Andy

garion wrote:

Andy Wade wrote:

That's a very bizarre layout - main switch in between two MCBs, RCD at
the other end. Have you looked inside to see how it's wired? Where do
the tails go in? A photo (with cover removed) would probably be quite
interesting, if you can put one up on the Web somewhere. Are you sure
everything goes through the RCD?



Havent even attempted to remove the cover yet.
(Dont know if I really want too!!)

Certainly seems to. If you turn the 100a switch off only lights go out,

if you turn RCD off everything goes off.


It sounds like they have used a split load board but transposed the RCD
and main switch. Then placed the lighting circuit on what should have
been the RCD protected side, and all the other circuits on what ought to
have been the non protected side. However the transposed RCD and switch
partially alters the first cockup!



--
Cheers,

John.

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