Apologies if this appears twice. Original appeared to disappear into the
ether

Hi

An electrician has recently installed a new consumer unit.

The unit has 8 mcbs for the eight circuits and one main off switch.
Between the incoming supply and the consumer unit is a single RCD which
therefore kills all the circuits if it operates.

Last night an earth/neutral fault on one circuit resulted in the RCD
tripping and no power to anywhere in the house. Since it was an
earth/neutral fault turning off all the mcbs still did not allow the RCD
to be re-set and hence no circuits could be used until the fault was
dealt with.

Under the 17th is it permitted to do this or should there be a dual RCD
board or part/all rcbos? Chapter 31?

TIA for any advice

Invisible Man wrote:

Under the 17th is it permitted to do this

No, single RCD setups like that went out shortly after 15th edition.

or should there be a dual RCD
board or part/all rcbos? Chapter 31?

Dual RCDs is probably the minimum. Depending on the number and type of
circuits more (or RCBOs) may be preferable.

--
Cheers,

John.

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

On Wed, 04 Mar 2009 22:26:12 +0000, Invisible Man wrote:

Apologies if this appears twice. Original appeared to disappear into the
ether

Hi

An electrician has recently installed a new consumer unit.

The unit has 8 mcbs for the eight circuits and one main off switch.
Between the incoming supply and the consumer unit is a single RCD which
therefore kills all the circuits if it operates.

Last night an earth/neutral fault on one circuit resulted in the RCD
tripping and no power to anywhere in the house. Since it was an
earth/neutral fault turning off all the mcbs still did not allow the RCD
to be re-set and hence no circuits could be used until the fault was
dealt with.

Under the 17th is it permitted to do this or should there be a dual RCD
board or part/all rcbos? Chapter 31?

TIA for any advice

My unit was changed about 15 years ago and has 2 RCDs: 100mA incoming split
to 30mA for the usual circuits. If a socket trips the 30mA one, the lights
stay on.
I don't know which issue of the Regs. were current then, but I'd mentioned
to the Council about my Father not being able to move around in darkness so
that might have been the reason.
--
Peter.
You don't understand Newton's Third Law of Motion?
It's not rocket science, you know.

PeterC wrote:

My unit was changed about 15 years ago and has 2 RCDs: 100mA incoming split
to 30mA for the usual circuits. If a socket trips the 30mA one, the lights
stay on.

That sounds more like a typical setup for a TT installation. Does he
have power supplied by overhead wires and/or is he out in the sticks a bit?

http://wiki.diyfaq.org.uk/index.php?title=TT_Earthing

I don't know which issue of the Regs. were current then, but I'd mentioned

16th probably

to the Council about my Father not being able to move around in darkness so
that might have been the reason.

The more commonly encounter comparable installation for non TT installs
would have been a similar arrangement but with the 100mA RCD replaced
with a simple switch.

--
Cheers,

John.

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

John Rumm wrote:
PeterC wrote:

My unit was changed about 15 years ago and has 2 RCDs: 100mA incoming
split
to 30mA for the usual circuits. If a socket trips the 30mA one, the
lights
stay on.

That sounds more like a typical setup for a TT installation. Does he
have power supplied by overhead wires and/or is he out in the sticks a bit?

http://wiki.diyfaq.org.uk/index.php?title=TT_Earthing

I don't know which issue of the Regs. were current then, but I'd
mentioned

16th probably

to the Council about my Father not being able to move around in
darkness so
that might have been the reason.

The more commonly encounter comparable installation for non TT installs
would have been a similar arrangement but with the 100mA RCD replaced
with a simple switch.

I am the OP and have a TT installation. 1960's house in a road with
mostly 100 plus year old houses and a 15th century pub (old coaching inn).

Invisible Man wrote:
John Rumm wrote:
PeterC wrote:

My unit was changed about 15 years ago and has 2 RCDs: 100mA incoming
split
to 30mA for the usual circuits. If a socket trips the 30mA one, the
lights
stay on.

That sounds more like a typical setup for a TT installation. Does he
have power supplied by overhead wires and/or is he out in the sticks a bit?

http://wiki.diyfaq.org.uk/index.php?title=TT_Earthing

I don't know which issue of the Regs. were current then, but I'd
mentioned

16th probably

to the Council about my Father not being able to move around in
darkness so
that might have been the reason.

The more commonly encounter comparable installation for non TT installs
would have been a similar arrangement but with the 100mA RCD replaced
with a simple switch.

I am the OP and have a TT installation. 1960's house in a road with
mostly 100 plus year old houses and a 15th century pub (old coaching inn).

A split CU with 2x RCDs would be a good option then. Same brand so you
can move the MCBs over. Whole house on one often works, but does risk
total loss of power.


NT

wrote:
Invisible Man wrote:
John Rumm wrote:
PeterC wrote:

My unit was changed about 15 years ago and has 2 RCDs: 100mA incoming
split
to 30mA for the usual circuits. If a socket trips the 30mA one, the
lights
stay on.
That sounds more like a typical setup for a TT installation. Does he
have power supplied by overhead wires and/or is he out in the sticks a bit?

http://wiki.diyfaq.org.uk/index.php?title=TT_Earthing

I don't know which issue of the Regs. were current then, but I'd
mentioned
16th probably

to the Council about my Father not being able to move around in
darkness so
that might have been the reason.
The more commonly encounter comparable installation for non TT installs
would have been a similar arrangement but with the 100mA RCD replaced
with a simple switch.

I am the OP and have a TT installation. 1960's house in a road with
mostly 100 plus year old houses and a 15th century pub (old coaching inn).

A split CU with 2x RCDs would be a good option then. Same brand so you
can move the MCBs over. Whole house on one often works, but does risk
total loss of power.


NT

Thanks. Even just the single split will mean not all the lights will go
out and we can use lights plugged into the power circuit on the floor
without lighting. Also means we can run an extension lead to the fridge
and freezer if necessary.
Perhaps the price of mcbos will nosedive eventually.