I will be changing my CU soon (from old 5-way fuse box). It is covered
by my extension work on full plans. A few questions:

1. I currently pay British Gas for my electricity. If I want someone
to come and upgrade from 60A to 100A and fit a breaker, do I contact
my supplier (BG) or the infrastructure poeple (e-on in Midlands ?)
Likely cost ?

2. The main fuse is in a brown plastic box with a slide-out section
with finger grips on it. What will be the design of this (so I know
the mechanics if I decide to pull it myself) ? Is it a captive fuse
that will be pulled out when I pull out the sliding section ? How hard
should I have to pull ? Is the fuse itself just like a very large
cartridge fuse ? Any pictures ?

3. If I find an RCD is tripping all the time on some circuit having
installed the new CU, can you get a slot-in "normal fuse" to use
temporarily until you have time to investigate and fix ?

4. I'll probably get 16-way split unit. Any preferred makes ?

5. Anything special / funny needed for 17th Ed wiring ? I've got the
onsite guide on order !

Thanks,
Simon.

sm_jamieson coughed up some electrons that declared:

I will be changing my CU soon (from old 5-way fuse box). It is covered
by my extension work on full plans. A few questions:

1. I currently pay British Gas for my electricity. If I want someone
to come and upgrade from 60A to 100A and fit a breaker, do I contact
my supplier (BG) or the infrastructure poeple (e-on in Midlands ?)
Likely cost ?


Hi

I believe the supplier is usually the place to start (BG). They will liase
with the meter operator and the network operator as appropriate.

Good move to request an isolator.

2. The main fuse is in a brown plastic box with a slide-out section
with finger grips on it. What will be the design of this (so I know
the mechanics if I decide to pull it myself) ? Is it a captive fuse
that will be pulled out when I pull out the sliding section ? How hard
should I have to pull ? Is the fuse itself just like a very large
cartridge fuse ? Any pictures ?

If it's old, I would think twice about pulling it. The old stuff has
occasionally been known to break apart in the hands, or the cable, if old
paper insulated, to go bang if disturbed (in a visit to hospital sort of
way - there be 300A or 500A fuses upstream in many cases).

Technically it's illegal to interfere with the cutout and meter but many do
pull the fuse, especially if the seal's missing. If in any doubt about the
state of the equipment, "don't" would be my advice. The guy from
the "board" will have been trained to handle old crap and will have the
necessary protective clothing required to do it safely.

3. If I find an RCD is tripping all the time on some circuit having
installed the new CU, can you get a slot-in "normal fuse" to use
temporarily until you have time to investigate and fix ?

If you're using RCBOs, swap for an MCB from the same maker.
If using a split way board, the so called "17th Edition" boards have
typically 3 busbars: 2 with RCD protection and one direct to the isolator.
Spare MCB on the unprotected busbar should do it.

4. I'll probably get 16-way split unit. Any preferred makes ?

Hager, Contactum, MK Sentry, Wylex, Eaton/MEM, Square-D. I don't have
personal experience of all of those but they're generally decent makes.
Pros and cons of course and prices vary.

Square-D (owned by Schneider Electric who are good) have an interesting
feature in that the busbar is fully shrouded and hidden round the back of
the devices.

5. Anything special / funny needed for 17th Ed wiring ? I've got the
onsite guide on order !

Major changes from the 16th:

RCD protection (30mA) required on:

a) All sockets (you may leave a couple out for fridge and freezer, sockets
must be marked)

b) All circuits to a location containing a bath or shower, even the feed to
the SELV transformer for any low voltage lights. This includes bedrooms
with en-suites. Sockets (except shaver sockets) 3m from zone 1.

c) In practise all circuits need RCD protection anyway, unless they are
buried 50mm or mechanically protected in other (specific and approved)
ways.

and

d) Zones in bathrooms changed - no zone 3 anymore.

e) Volt drops on final circuits used to be 4% of nominal (230V). It's now 3%
for lighting and 5% for everything else. Unlikely to be a problem.

I might have forgotton something - hang around...

Cheers

Tim

If you're using RCBOs, swap for an MCB from the same maker.
If using a split way board, the so called "17th Edition" boards have
typically 3 busbars: 2 with RCD protection and one direct to the isolator.
Spare MCB on the unprotected busbar should do it.


Is this to use different RCDs for sockets and lighting ?

Reasons not to use all RCBOs ? How much more expensive or unreliable
are they than separate RCD and MCB ?


Major changes from the 16th:

RCD protection (30mA) required on:

a) All sockets (you may leave a couple out for fridge and freezer, sockets
must be marked)

b) All circuits to a location containing a bath or shower, even the feed to
the SELV transformer for any low voltage lights. This includes bedrooms
with en-suites. Sockets (except shaver sockets) 3m from zone 1.

c) In practise all circuits need RCD protection anyway, unless they are
buried 50mm or mechanically protected in other (specific and approved)
ways.

and

d) Zones in bathrooms changed - no zone 3 anymore.

e) Volt drops on final circuits used to be 4% of nominal (230V). It's now 3%
for lighting and 5% for everything else. Unlikely to be a problem.


Thanks,
Simon.

sm_jamieson wrote:

Reasons not to use all RCBOs ? How much more expensive

LOTS!

About £25 per RCBO rather than £3 per MCB plus £30 for an RCD (or £60
for two for 17th ed I suppose)

sm_jamieson coughed up some electrons that declared:


If you're using RCBOs, swap for an MCB from the same maker.
If using a split way board, the so called "17th Edition" boards have
typically 3 busbars: 2 with RCD protection and one direct to the
isolator. Spare MCB on the unprotected busbar should do it.


Is this to use different RCDs for sockets and lighting ?

Almost: One of the better ways is to do something like:

RCD1 GF lights, FF sockets

RCD2 FF lights, GF sockets

Then split the rest of the load between the two.

The idea is that a fault caused by running a device plugged in doesn't
plunge you into darkness. It plunges the person on the other floor into
darkness instead. Again, no hard and fast answers - and personal
circumstances might sway the descision.

Reasons not to use all RCBOs ? How much more expensive or unreliable
are they than separate RCD and MCB ?

Should be no difference in reliability. 2 RCDs is the practical minimum. All
RCBOs obviously segregates faults better. The other aspect, is if you have
a lot of equipment which is leaky due to mains filters or otherwise (eg
refridgeration, computers) then with RCBOs you get more budget per circuit.

Anyway, it's an issue with no absolute right answer. I'm putting in all
RCBOs, but the extra money is tiny compared to the budget for the whole
renovation project.

Cheers

Tim

In article ,
sm_jamieson writes:
3. If I find an RCD is tripping all the time on some circuit having
installed the new CU, can you get a slot-in "normal fuse" to use
temporarily until you have time to investigate and fix ?

If you have space to mount both CU's, then you can temporarily
wire the new one from a spare high current way in the old one.
Then you can try each of the circuits on the new CU and fix any
such RCD issues. Depending on your total loading, you could
leave some or all the circuits on the new CU (might have to leave
a cooker and/or shower behind), and then have the tails moved
across when you already know all the circuits work.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 13 Nov, 12:58, Tim S wrote:
sm_jamieson coughed up some electrons that declared:



If you're using RCBOs, swap for an MCB from the same maker.
If using a split way board, the so called "17th Edition" boards have
typically 3 busbars: 2 with RCD protection and one direct to the
isolator. Spare MCB on the unprotected busbar should do it.

Is this to use different RCDs for sockets and lighting ?

Almost: One of the better ways is to do something like:

RCD1 GF lights, FF sockets

RCD2 FF lights, GF sockets

Then split the rest of the load between the two.

The idea is that a fault caused by running a device plugged in doesn't
plunge you into darkness. It plunges the person on the other floor into
darkness instead. Again, no hard and fast answers - and personal
circumstances might sway the descision.

Reasons not to use all RCBOs ? How much more expensive or unreliable
are they than separate RCD and MCB ?

Should be no difference in reliability. 2 RCDs is the practical minimum. All
RCBOs obviously segregates faults better. The other aspect, is if you have
a lot of equipment which is leaky due to mains filters or otherwise (eg
refridgeration, computers) then with RCBOs you get more budget per circuit.

Anyway, it's an issue with no absolute right answer. I'm putting in all
RCBOs, but the extra money is tiny compared to the budget for the whole
renovation project.

Cheers

Tim

Thanks for the info.

Do MCBs and RCBOs fit into the same type of slot in the CU ?
Are these devices compatible between manufacturers ?

Simon.

sm_jamieson coughed up some electrons that declared:

On 13 Nov, 12:58, Tim S wrote:
sm_jamieson coughed up some electrons that declared:



If you're using RCBOs, swap for an MCB from the same maker.
If using a split way board, the so called "17th Edition" boards have
typically 3 busbars: 2 with RCD protection and one direct to the
isolator. Spare MCB on the unprotected busbar should do it.

Is this to use different RCDs for sockets and lighting ?

Almost: One of the better ways is to do something like:

RCD1 GF lights, FF sockets

RCD2 FF lights, GF sockets

Then split the rest of the load between the two.

The idea is that a fault caused by running a device plugged in doesn't
plunge you into darkness. It plunges the person on the other floor into
darkness instead. Again, no hard and fast answers - and personal
circumstances might sway the descision.

Reasons not to use all RCBOs ? How much more expensive or unreliable
are they than separate RCD and MCB ?

Should be no difference in reliability. 2 RCDs is the practical minimum.
All RCBOs obviously segregates faults better. The other aspect, is if you
have a lot of equipment which is leaky due to mains filters or otherwise
(eg refridgeration, computers) then with RCBOs you get more budget per
circuit.

Anyway, it's an issue with no absolute right answer. I'm putting in all
RCBOs, but the extra money is tiny compared to the budget for the whole
renovation project.

Cheers

Tim

Thanks for the info.

Do MCBs and RCBOs fit into the same type of slot in the CU ?

Generally they do, thing to look for is: is the CU capable of taking RCBOs
(they are much taller than MCBs, unless they are double width types).
If so, MCBs from either part or all of the manufacturer's range will fit.

Generally the more domestic kit (as opposed to industrial) have a range of
MCBS, RCBOs, Dp isolator, RCCBs that are compatible with the current range
of CUs by the same maker. Most manufacturers have downloadable brochures
and datasheets, but if you were to buy from the local wholesaler, then
select your CU and give them a list of the MCBs and RCBO by characteristic
and they should be able to furnish you with a kit of parts that work.

Are these devices compatible between manufacturers ?

No. Even if they fit, you've ruined any notion of the CU being "type tested"
which means if it goes bang, overheats or otherwise fails, it's your fault.

Cheers

Tim

Thanks for the info so far.
Seen on screwfix site - what do these mean ?

* Select Incomer

* Floating Busbar

Cheers,
Simon.

Any comments on the following, a list of circuits for my CU
replacement.
It seems that even a 16-slot would be too small, given the amount of
slots used by two double-pole RCDs and another double-pole switch for
the non-RCD bus.
Proposed CU circuits:

lights downstairs
lights 1st floor
lights loft
sockets downstairs (not kitchen)
sockets 1st floor
sockets loft
sockets kitchen ring (RCD)
sockets kitchen radial (non-RCD / fridge)
sockets kitchen cooker (30A ?)
lights outside
sockets outside
power to garage / shed (mini-CU in there eventually)
electric shower
light in meter cupboard

These seem like logical groupings.
How do folks manage with less ?
How should I combine these ?

Simon.

Hi,

sm_jamieson coughed up some electrons that declared:

Any comments on the following, a list of circuits for my CU
replacement.
It seems that even a 16-slot would be too small, given the amount of
slots used by two double-pole RCDs and another double-pole switch for
the non-RCD bus.
Proposed CU circuits:

lights downstairs

OK

lights 1st floor
lights loft

I'd combine these, unless you're planning to run 500W in the loft or are
concerned about the 1st floor and loft going dark at the same time?? Is it
likely?

sockets downstairs (not kitchen)

Good idea

sockets 1st floor

OK

sockets loft

Combine with 1st floor ring?

sockets kitchen ring (RCD)

Good idea, big loads in the kitchen

sockets kitchen radial (non-RCD / fridge)

OK - but you need to mark the sockets as such AND protect the cable, which
means:

MICC (aka "pyro", not practical unless you can do the terminations)

SWA Armoured (Bit excessive but fairly practical if all else fails, not
actually as stupid as it sounds)

Steel conduit (yuk, bending and threading will be hard work) (metal capping
is NOT acceptable),

Earth-foil-screen cable (there's a BS, can look up, but eg: Flexishield,
X-Shield, and others - has caveats but probably easy to work with and
practical. Difficult to buy and expensive. RS sometimes have it if you buy
an entire drum.

Or run the cable on the surface and/or 50mm below wall/ceiling/floor
surfaces. Mini trunking is acceptable.

sockets kitchen cooker (30A ?)

Do you mean a cooker circuit? Depending on wheather this has an integral 13A
socket, fusing could vary from 32A to 45A. Best size the cable for 45A and
put a breaker in to suit your cooker.

lights outside

Good idea

sockets outside

Ditto

power to garage / shed (mini-CU in there eventually)

Yep

electric shower

Yes

light in meter cupboard

Given you could run the cable on the surface here, thus not need an RCD,
MCBs are cheap as chips, so why not? I see why you think this is a good
idea. Other option is emergency light fitting which works in a power cut
too.

These seem like logical groupings.
How do folks manage with less ?
How should I combine these ?


Sure there'll be some different opinions. I've tried to explain why I'm made
my statements, but again, it's not hard and fast.

HTH

Tim

sm_jamieson wrote:

General guidance on changing a CU he

http://wiki.diyfaq.org.uk/index.php?..._consumer_unit


2. The main fuse is in a brown plastic box with a slide-out section
with finger grips on it. What will be the design of this (so I know
the mechanics if I decide to pull it myself) ? Is it a captive fuse
that will be pulled out when I pull out the sliding section ? How hard
should I have to pull ? Is the fuse itself just like a very large
cartridge fuse ? Any pictures ?


It will probably be a captive large cartridge fuse that stays in the bit
you pull. This will normally have "fingers" on it that connect to the
fuse and poke into the bit fixed to the wall. To pull it you usually
remove any wire seals if there are any, cut any paper ones, grab by the
finger grips and pull[1]. The amount of pull required will normally be
no more than that required to withdraw a plug from a socket.

There is one example he

http://wiki.diyfaq.org.uk/index.php?...utandMeter.jpg

On that one the whole front bit come off revealing the terminals for
both ends of the fuse, slight shrouded (but on that one, you could poke
a finger into the live end if you wanted!). Normally with these I cover
the live end with some tape as a precaution against something
accidentally getting poked in there when working near it.

[1] Make sure there is no electrical load on the fuse when you pull it -
e.g. turn the main switch off on the CU.


--
Cheers,

John.

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

On 13 Nov, 16:48, sm_jamieson wrote:

light in meter cupboard

I've just acquired a metere cupboard where there's a non-maintained
light in there (comes _on_ when power fails), quite a handy idea!

sm_jamieson wrote:

Any comments on the following, a list of circuits for my CU
replacement.
It seems that even a 16-slot would be too small, given the amount of
slots used by two double-pole RCDs and another double-pole switch for
the non-RCD bus.

Normally when they say 16 way, that is the number of free ways with the
RCDs/Switch in place. So if the board is a three way split with some
switch ways and two lots of RCD protected ways, then the 16 ways will be
over and above the six occupied by the switch and pair of RCDs.


Proposed CU circuits:

lights downstairs
lights 1st floor
lights loft

If "loft" is just a loft, then no need for a separate circuit. If its a
converted loft with several rooms, then that is different.

sockets downstairs (not kitchen)
sockets 1st floor
sockets loft

see comment above/

sockets kitchen ring (RCD)
sockets kitchen radial (non-RCD / fridge)
sockets kitchen cooker (30A ?)

Did you mean "sockets" there?

lights outside
sockets outside

These would be better of on RCBOs in the non RCD section of the board,
or on their own RCD if you have more splits.

power to garage / shed (mini-CU in there eventually)
electric shower
light in meter cupboard

A "maintained" emergency light hooked up to whatever circuit illuminates
the floor nearest the CU works well here. You can use it with a switch
to light the cupboard for day to day stuff, but if the power to the
circuit is interrupted then it will light from batteries. It makes
finding a CU in the dark to reset a trip much simpler.

These seem like logical groupings.

yup

How do folks manage with less ?

Older installs may only have up and downstairs sockets - no kitchen etc.
Might even only have a single socket circuit etc.

How should I combine these ?

There are lots of ways, you need to think about how you are going to use
the system, and what the implications of trips will be.

--
Cheers,

John.

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

"Andy Dingley" wrote in message
...
On 13 Nov, 16:48, sm_jamieson wrote:

light in meter cupboard

I've just acquired a metere cupboard where there's a non-maintained
light in there (comes _on_ when power fails), quite a handy idea!

Not half as good as having a wind up torch in there.

On 13 Nov, 18:22, John Rumm wrote:
sm_jamieson wrote:
Any comments on the following, a list of circuits for my CU
replacement.
It seems that even a 16-slot would be too small, given the amount of
slots used by two double-pole RCDs and another double-pole switch for
the non-RCD bus.

Normally when they say 16 way, that is the number of free ways with the
RCDs/Switch in place. So if the board is a three way split with some
switch ways and two lots of RCD protected ways, then the 16 ways will be
over and above the six occupied by the switch and pair of RCDs.

OK, would that be the case with this - it looks like an empty case ?
http://www.screwfix.com/prods/30776


Proposed CU circuits:

lights downstairs
lights 1st floor
lights loft

If "loft" is just a loft, then no need for a separate circuit. If its a
converted loft with several rooms, then that is different.

Will be converted as next major job !


sockets downstairs (not kitchen)
sockets 1st floor
sockets loft

see comment above/

sockets kitchen ring (RCD)
sockets kitchen radial (non-RCD / fridge)
sockets kitchen cooker (30A ?)

Did you mean "sockets" there?

I meant a standard cooker circuit.


lights outside
sockets outside

These would be better of on RCBOs in the non RCD section of the board,
or on their own RCD if you have more splits.

power to garage / shed (mini-CU in there eventually)
electric shower
light in meter cupboard

A "maintained" emergency light hooked up to whatever circuit illuminates
the floor nearest the CU works well here. You can use it with a switch
to light the cupboard for day to day stuff, but if the power to the
circuit is interrupted then it will light from batteries. It makes
finding a CU in the dark to reset a trip much simpler.

These seem like logical groupings.

yup

How do folks manage with less ?

Older installs may only have up and downstairs sockets - no kitchen etc.
Might even only have a single socket circuit etc.

How should I combine these ?

There are lots of ways, you need to think about how you are going to use
the system, and what the implications of trips will be.

Thanks,
Simon.

Owain coughed up some electrons that declared:

Tim S wrote:
lights 1st floor
lights loft
I'd combine these, unless you're planning to run 500W in the loft or are
concerned about the 1st floor and loft going dark at the same time?? Is
it likely?

I'd keep them separate. One reason for being in the loft would be to
work on the 1st floor lighting. Bit awkward if they're on the same
circuit.

Owain

Good point.

sm_jamieson coughed up some electrons that declared:


OK, would that be the case with this - it looks like an empty case ?
http://www.screwfix.com/prods/30776

It is - you'd have to buy all the bits right down to the busbar.

Try this - it's more like what you want:

http://www.tlc-direct.co.uk/Main_Ind...its/index.html

Personally, I wouldn't bother with screwfix for this sort of thing, it's not
their strong point.

Cheers

Tim

On 13 Nov, 19:42, Tim S wrote:
sm_jamieson coughed up some electrons that declared:

OK, would that be the case with this - it looks like an empty case ?
http://www.screwfix.com/prods/30776

It is - you'd have to buy all the bits right down to the busbar.

Try this - it's more like what you want:

http://www.tlc-direct.co.uk/Main_Ind...ndex/MK_17_Con...


Hey, fantastic. If that 15-way CU won't do nothing will.
The PDF doc available is also very useful.
Now just to decide the ratings for each circuit etc.

Thanks.
Simon.

sm_jamieson coughed up some electrons that declared:

On 13 Nov, 19:42, Tim S wrote:
sm_jamieson coughed up some electrons that declared:

OK, would that be the case with this - it looks like an empty case ?
http://www.screwfix.com/prods/30776

It is - you'd have to buy all the bits right down to the busbar.

Try this - it's more like what you want:

http://www.tlc-direct.co.uk/Main_Ind...ndex/MK_17_Con...


Hey, fantastic. If that 15-way CU won't do nothing will.
The PDF doc available is also very useful.
Now just to decide the ratings for each circuit etc.

Thanks.
Simon.

If you want to go on a total web bender, try:

www.hager.co.uk

and go to Downloads, then Catalogues. Then grab "1 Consumer Units". Loads of
options, metal, plastic, surface, flush and weatherproof. And a vast
collection of devices in other catalogue sections. Price is similar to MK
and the reputation is good. MK's web site (google for mk electric) is
utterly crap, but if you poke around there's a similar PDF to download.

Cheers

Tim

sm_jamieson wrote:
On 13 Nov, 19:42, Tim S wrote:
sm_jamieson coughed up some electrons that declared:

OK, would that be the case with this - it looks like an empty case ?
http://www.screwfix.com/prods/30776
It is - you'd have to buy all the bits right down to the busbar.

Try this - it's more like what you want:

http://www.tlc-direct.co.uk/Main_Ind...ndex/MK_17_Con...


Hey, fantastic. If that 15-way CU won't do nothing will.

One point worth checking is that you have enough room to install your
chosen CU - the larger ones are surprisingly wide, and that can be a
problem when working in a cupboard etc.

--
Cheers,

John.

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

sm_jamieson wrote:

2. The main fuse is in a brown plastic box with a slide-out section
with finger grips on it. What will be the design of this (so I know
the mechanics if I decide to pull it myself) ? Is it a captive fuse
that will be pulled out when I pull out the sliding section ? How hard
should I have to pull ? Is the fuse itself just like a very large
cartridge fuse ? Any pictures ?

I'd recommend having some gaffer tape handy. Mine when pulled out leaves
a big (like two inch by one inch) inviting hole with big bare contacts
in in. Far too much possibility of getting a stray finger, tool, or the
other end of a wire into it by mistake - tape it over while you're working.

Pete

Pete Verdon wrote:

Mine when pulled out leaves
a big (like two inch by one inch) inviting hole with big bare contacts
in in. Far too much possibility of getting a stray finger, tool, or the
other end of a wire into it by mistake - tape it over while you're working.

Or remove the main fuse from carrier (stick it in your pocket etc) and
replace the empty carrier?

One other point. All of the existing wiring is in red and black.
When fitting a new CU, where should I change to the new colours ? If I
change any wiring before the CU, is it OK to have a mix of red/black
and blue/brown here ?
Thanks,
Simon.

sm_jamieson coughed up some electrons that declared:

One other point. All of the existing wiring is in red and black.
When fitting a new CU, where should I change to the new colours ? If I
change any wiring before the CU, is it OK to have a mix of red/black
and blue/brown here ?
Thanks,
Simon.

Yes it's OK, but you must apply one of these to the outside:

http://www.tlc-direct.co.uk/Products/TLLAB50.html

to warn anyone coming after you.

Cheers

Tim

OK, trying to get the number of circuits down. Nice to have separate
fixed appliance radial in kitchen, but takes up another slot. So ...
In kitchen some fixed appliances and various sockets. If fixed
appliances off a 32A ring (e.g. 32A MCB) plus kettle etc., could get a
bit close to limits.
Is it permitted to have a higher powered ring for the kitchen, using
4mm cable ?
Simon.

sm_jamieson coughed up some electrons that declared:

OK, trying to get the number of circuits down. Nice to have separate
fixed appliance radial in kitchen, but takes up another slot. So ...
In kitchen some fixed appliances and various sockets. If fixed
appliances off a 32A ring (e.g. 32A MCB) plus kettle etc., could get a
bit close to limits.
Is it permitted to have a higher powered ring for the kitchen, using
4mm cable ?
Simon.

Not to my knowledge as I believe a ring final circuit is a special case
final circuit defined as 32A max, with cables to be designed for 20A or
greater.

You can have radial circuits too, but IIRC the BS for 13A sockets defines
the socket terminals as capable of taking:

3x2.5mm2
or
2x4mm2

So it's often not easy to get to 32A let alone beyond, many radials operate
at 20A, maybe 25A.

HTH

Tim

sm_jamieson wrote:
OK, trying to get the number of circuits down. Nice to have separate
fixed appliance radial in kitchen, but takes up another slot. So ...
In kitchen some fixed appliances and various sockets. If fixed
appliances off a 32A ring (e.g. 32A MCB) plus kettle etc., could get a
bit close to limits.

You can normally ignore things like kettles in domestic loading
estimates since they are such short term loads.

Is it permitted to have a higher powered ring for the kitchen, using
4mm cable ?

Not that I am aware of. You could of course have more than one if you
needed.

--
Cheers,

John.

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

Yes it's OK, but you must apply one of these to the outside:

http://www.tlc-direct.co.uk/Products/TLLAB50.html

to warn anyone coming after you.

I've occasionally wondered what practical problem this is supposed to
prevent in a domestic setting. I understand that the colours for
three-phase have changed in an undesirable way (neutral / phase swap, is
it?) but there's no such confusion in a single-phase system. Black and
blue are both always neutral, red and brown are both always live.
Tradesmen and DIYers are going to be aware of the old colours for many
decades yet as they show up in existing installations. And even if some
new kid in 2080 doesn't know what this red conductor is that he's found,
I doubt the actual wording on that sticker would help anyway.

Still, for 30p I stuck one on - nice to make things look official :-)

Pete

Pete Verdon wrote:
Tim S wrote:

Yes it's OK, but you must apply one of these to the outside:

http://www.tlc-direct.co.uk/Products/TLLAB50.html

to warn anyone coming after you.

I've occasionally wondered what practical problem this is supposed to
prevent in a domestic setting. I understand that the colours for
three-phase have changed in an undesirable way (neutral / phase swap, is
it?) but there's no such confusion in a single-phase system. Black and

Blue was a phase and is now neutral, Black was neutral and is now a phase.

blue are both always neutral, red and brown are both always live.

You may meet some 3&E with a live black conductor on two way light
switching.

Tradesmen and DIYers are going to be aware of the old colours for many
decades yet as they show up in existing installations. And even if some
new kid in 2080 doesn't know what this red conductor is that he's found,
I doubt the actual wording on that sticker would help anyway.

Indeed.

Still, for 30p I stuck one on - nice to make things look official :-)

;-)

--
Cheers,

John.

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

Pete Verdon wrote:

[...] but there's no such confusion in a single-phase system. Black and
blue are both always neutral,

Until you come to 3-core(+E) cable in lighting circuits, where a blue
core could be either neutral or switched line (old colours) and black
may be switched line (new colours). Of course these should be marked at
terminations with sleeving but you have to allow for the reality that
such marking was often not fitted, or tape was used and has fallen off.

The new colours label just alerts you to the fact that mixed colours are
in use and that care should be taken. It's a concession compared to the
requirements in a 3-phase installation where core marking is required at
all junctions between old and new wiring.

--
Andy

On Sun, 16 Nov 2008 00:59:41 +0000, Andy Wade
wrote:

Pete Verdon wrote:

[...] but there's no such confusion in a single-phase system. Black and
blue are both always neutral,

Until you come to 3-core(+E) cable in lighting circuits, where a blue
core could be either neutral or switched line (old colours) and black
may be switched line (new colours). Of course these should be marked at
terminations with sleeving but you have to allow for the reality that
such marking was often not fitted, or tape was used and has fallen off.

The new colours label just alerts you to the fact that mixed colours are
in use and that care should be taken.

Surely care should be taken anyway! Anybody not realising that
shouldn't be messing about in a CU...

;-))

--
Frank Erskine

"Andy Wade" wrote in message
...
Pete Verdon wrote:

[...] but there's no such confusion in a single-phase system. Black and
blue are both always neutral,

Until you come to 3-core(+E) cable in lighting circuits, where a blue core
could be either neutral or switched line (old colours) and black may be
switched line (new colours). Of course these should be marked at
terminations with sleeving but you have to allow for the reality that such
marking was often not fitted, or tape was used and has fallen off.

Of course in the most common use of three core and earth they are all live.