Quick question...
Is a single RCD protecting everything ever acceptable now?

Long version...
Mate has a flat (2 bedrooms, all on one level) with an old wire fuse
consumer unit.

It has 4 circuits
Lights
Sockets
Oven
Immersion (now just a socket)

He is planning on moving out of this flat and letting it, so has asked a
sparks to quote for a CU upgrade.

He has been quoted for a 6 way CU with an RCD and MCB's.

Is this going to be compliant?

I suggested before the sparks came round he would be beast getting a CU with
a main switch and three RCBO's (connecting the old immersion feed to the
sockets RCBO as there isn't a hot water cylinder anymore) as Regulation
314.1 says "Every installation shall be divided into circuits as necessary
to avoid danger and inconvenience in the event of a fault, take account of
danger that may arise from the failure of a single circuit such as a
lighting circuit, reduce the possibility of unwanted tripping of RCDs etc."

Thanks!

Toby...

"Toby" wrote in message
...
Quick question...
Is a single RCD protecting everything ever acceptable now?

Long version...
Mate has a flat (2 bedrooms, all on one level) with an old wire fuse
consumer unit.

It has 4 circuits
Lights
Sockets
Oven
Immersion (now just a socket)

He is planning on moving out of this flat and letting it, so has asked a
sparks to quote for a CU upgrade.

He has been quoted for a 6 way CU with an RCD and MCB's.

Is this going to be compliant?

I suggested before the sparks came round he would be beast getting a CU
with a main switch and three RCBO's (connecting the old immersion feed to
the sockets RCBO as there isn't a hot water cylinder anymore) as
Regulation 314.1 says "Every installation shall be divided into circuits
as necessary to avoid danger and inconvenience in the event of a fault,
take account of danger that may arise from the failure of a single circuit
such as a lighting circuit, reduce the possibility of unwanted tripping of
RCDs etc."

Thanks!

Toby...
Why upgrade? There is no requirement to retrofit to the latest wiring
standard unless perhaps other major alterations are required. The sparky
should have just noted on the test cert 'not in accordance with latest
wiring regs', which is perfectly acceptable; sounds like sparky is short of
work.... Just make sure your mate gets a completed Periodic Test Report with
no serious outstanding items. The main disadvantage of ONE RCD is theres no
discrimination so you lose everything if it trips, not ideal but tolerable.

S

"Mitch" x wrote in message
o.uk...

"Toby" wrote in message
...
Quick question...
Is a single RCD protecting everything ever acceptable now?

Long version...
Mate has a flat (2 bedrooms, all on one level) with an old wire fuse
consumer unit.

It has 4 circuits
Lights
Sockets
Oven
Immersion (now just a socket)

He is planning on moving out of this flat and letting it, so has asked a
sparks to quote for a CU upgrade.

He has been quoted for a 6 way CU with an RCD and MCB's.

Is this going to be compliant?

I suggested before the sparks came round he would be beast getting a CU
with a main switch and three RCBO's (connecting the old immersion feed to
the sockets RCBO as there isn't a hot water cylinder anymore) as
Regulation 314.1 says "Every installation shall be divided into circuits
as necessary to avoid danger and inconvenience in the event of a fault,
take account of danger that may arise from the failure of a single
circuit such as a lighting circuit, reduce the possibility of unwanted
tripping of RCDs etc."

Thanks!

Toby...
Why upgrade? There is no requirement to retrofit to the latest wiring
standard unless perhaps other major alterations are required. The sparky
should have just noted on the test cert 'not in accordance with latest
wiring regs', which is perfectly acceptable;



sounds like sparky is short of work....

Are you sure? Sparky gets a phone call saying "Can you give me a price for a
new CU?" and Sparky then gives a price for a new CU.

Just make sure your mate gets a completed Periodic Test Report with
no serious outstanding items. The main disadvantage of ONE RCD is theres
no discrimination so you lose everything if it trips, not ideal but
tolerable.

I would want to see RCBOs used, especially on such a small CU.

Adam

"ARWadsworth" wrote in message
news:a%mUn.6554$9c1.4632@hurricane...

"Mitch" x wrote in message
o.uk...

"Toby" wrote in message
...
Quick question...
Is a single RCD protecting everything ever acceptable now?

Long version...
Mate has a flat (2 bedrooms, all on one level) with an old wire fuse
consumer unit.

It has 4 circuits
Lights
Sockets
Oven
Immersion (now just a socket)

He is planning on moving out of this flat and letting it, so has asked a
sparks to quote for a CU upgrade.

He has been quoted for a 6 way CU with an RCD and MCB's.

Is this going to be compliant?

I suggested before the sparks came round he would be beast getting a CU
with a main switch and three RCBO's (connecting the old immersion feed
to the sockets RCBO as there isn't a hot water cylinder anymore) as
Regulation 314.1 says "Every installation shall be divided into circuits
as necessary to avoid danger and inconvenience in the event of a fault,
take account of danger that may arise from the failure of a single
circuit such as a lighting circuit, reduce the possibility of unwanted
tripping of RCDs etc."

Thanks!

Toby...
Why upgrade? There is no requirement to retrofit to the latest wiring
standard unless perhaps other major alterations are required. The sparky
should have just noted on the test cert 'not in accordance with latest
wiring regs', which is perfectly acceptable;



sounds like sparky is short of work....

Are you sure? Sparky gets a phone call saying "Can you give me a price for
a new CU?" and Sparky then gives a price for a new CU.

Just make sure your mate gets a completed Periodic Test Report with
no serious outstanding items. The main disadvantage of ONE RCD is theres
no discrimination so you lose everything if it trips, not ideal but
tolerable.

I would want to see RCBOs used, especially on such a small CU.

Adam

Thanks Adam, I was hoping you might see this!

Main reason for the change is to bring it up to current standards to show he
has taken all the necessary steps to prevent any problems later on if
someone electrocuted themselves while renting the flat.

Although RCBO's are clearly the way to go, is it still permitted to use just
the one RCD in this case?

Thanks!

Toby...

"John Rumm" wrote in message
o.uk...
On 22/06/2010 20:59, Toby wrote:

Quick question...
Is a single RCD protecting everything ever acceptable now?

Rarely... if it was a secondary CU in a shed or garage it might be...

Long version...
Mate has a flat (2 bedrooms, all on one level) with an old wire fuse
consumer unit.

It has 4 circuits
Lights
Sockets
Oven
Immersion (now just a socket)

He is planning on moving out of this flat and letting it, so has asked a
sparks to quote for a CU upgrade.

He has been quoted for a 6 way CU with an RCD and MCB's.

Split load or just "normal"

The quote just has
"Remove old fuse board
Install new 6 way rcd protected consumer unit
Install all new MCBS
Install all circuits
Test all circuits & record
Issue domestic electrical installation certificate"

Which I read as just one RCD, and not a split load
Having a split load with two RCD's seems bonkers anyway.

I assume the certificate here is just for the new CU, and is not a
certificate he can use to show it has all been tested?



Is this going to be compliant?

Not really. If its a normal CU with all the circuits on the RCD then it
lacks discrimination between the lights and power circuits. If its a split
load with the lights on the non RCD side, then it probably fails on the
17th edition requirements for concealed cable protection with a RCD.
Although this solution may become ok under amendment 1 of the 17th
edition - where you can argue that retrofitting an RCD is not required if
there is no significant risk from the circuit.

Okay, didn't know about that - although in his case there is a 240v fan in
the bathroom, quite close to the bath, so I would want to see that RCD'd
myself.

I suggested before the sparks came round he would be beast getting a CU
with a main switch and three RCBO's (connecting the old immersion feed
to the sockets RCBO as there isn't a hot water cylinder anymore) as

Yup, for a small setup like this, and all RCBO setup seems sensible.


Thaks for the comments John!

Toby...

"Toby" wrote in message
...
"ARWadsworth" wrote in message
news:a%mUn.6554$9c1.4632@hurricane...

"Mitch" x wrote in message
o.uk...

"Toby" wrote in message
...
Quick question...
Is a single RCD protecting everything ever acceptable now?

Long version...
Mate has a flat (2 bedrooms, all on one level) with an old wire fuse
consumer unit.

It has 4 circuits
Lights
Sockets
Oven
Immersion (now just a socket)

He is planning on moving out of this flat and letting it, so has asked
a sparks to quote for a CU upgrade.

He has been quoted for a 6 way CU with an RCD and MCB's.

Is this going to be compliant?

I suggested before the sparks came round he would be beast getting a CU
with a main switch and three RCBO's (connecting the old immersion feed
to the sockets RCBO as there isn't a hot water cylinder anymore) as
Regulation 314.1 says "Every installation shall be divided into
circuits as necessary to avoid danger and inconvenience in the event of
a fault, take account of danger that may arise from the failure of a
single circuit such as a lighting circuit, reduce the possibility of
unwanted tripping of RCDs etc."

Thanks!

Toby...
Why upgrade? There is no requirement to retrofit to the latest wiring
standard unless perhaps other major alterations are required. The sparky
should have just noted on the test cert 'not in accordance with latest
wiring regs', which is perfectly acceptable;



sounds like sparky is short of work....

Are you sure? Sparky gets a phone call saying "Can you give me a price
for a new CU?" and Sparky then gives a price for a new CU.

Just make sure your mate gets a completed Periodic Test Report with
no serious outstanding items. The main disadvantage of ONE RCD is theres
no discrimination so you lose everything if it trips, not ideal but
tolerable.

I would want to see RCBOs used, especially on such a small CU.

Adam

Thanks Adam, I was hoping you might see this!

Main reason for the change is to bring it up to current standards to show
he has taken all the necessary steps to prevent any problems later on if
someone electrocuted themselves while renting the flat.

Although RCBO's are clearly the way to go, is it still permitted to use
just the one RCD in this case?

Thanks!

Toby...

I say that some discimination is needed (you answered that correctly
yourself) and RCBOs should be used. I would also go as far to say that there
should be 4 RCBOs, with the old immersion having it's own one. If there is a
problem with the sockets[1] and the RCBO trips then at least the tenants
will have one power supply to plug their fridge/freezer into until the fault
is fixed.

[1] They always trip on a Friday before a Bank Holiday - ask any landlord!

4 RCBOs would add about £100 to the cost of replacing the fusebox.

Cheers

Adam

"Toby" wrote in message
...
He has been quoted for a 6 way CU with an RCD and MCB's.

Split load or just "normal"

The quote just has
"Remove old fuse board
Install new 6 way rcd protected consumer unit
Install all new MCBS
Install all circuits
Test all circuits & record
Issue domestic electrical installation certificate"

Which I read as just one RCD, and not a split load
Having a split load with two RCD's seems bonkers anyway.

It would be bonkers on a set up like yours! And that is a quote for an RCD
main switch.

I assume the certificate here is just for the new CU, and is not a
certificate he can use to show it has all been tested?

The certificte should be as good as a PIR certificate.
I actually do the tests before changing the fuse box. If there are any
nasties then at least I can warn the customer before I start to change the
board.

Cheers

Adam

"John Rumm" wrote in message
.. .
On 23/06/2010 13:49, Toby wrote:
"John wrote in message
o.uk...
On 22/06/2010 20:59, Toby wrote:

Quick question...
Is a single RCD protecting everything ever acceptable now?

Rarely... if it was a secondary CU in a shed or garage it might be...

Long version...
Mate has a flat (2 bedrooms, all on one level) with an old wire fuse
consumer unit.

It has 4 circuits
Lights
Sockets
Oven
Immersion (now just a socket)

He is planning on moving out of this flat and letting it, so has asked
a
sparks to quote for a CU upgrade.

He has been quoted for a 6 way CU with an RCD and MCB's.

Split load or just "normal"

The quote just has
"Remove old fuse board
Install new 6 way rcd protected consumer unit
Install all new MCBS
Install all circuits
Test all circuits& record
Issue domestic electrical installation certificate"

Which I read as just one RCD, and not a split load

Sounds like it, unless he means a 17th edition style one with two RCDs

Maybe, but it doesn't look like it, I would expect it ti say "Split load" in
this case


Having a split load with two RCD's seems bonkers anyway.

Why?

Because he only needs three circuts, so that would mean one RCD is covering
just the one MCB and the other one just 2 - surely RCBOs are the beeter
choice!

I assume the certificate here is just for the new CU, and is not a
certificate he can use to show it has all been tested?

Well he will also need to do some tests on the reconnected circuits.

Okay, didn't know about that - although in his case there is a 240v fan
in
the bathroom, quite close to the bath, so I would want to see that RCD'd
myself.

Which circuit is it powered from though?

Lighting, like a normal bathroom fan.

Toby...