Hi,

Just a quick question;

If I replace my rewirable fuses with plugin mcbs - do I use like for like?
My fuses are 5 amp, 20 amp, and 30 amp. Should I get the same values, or
should I replace the 5 amp with a 6 amp, and the 30 amp with 32 amp?

The reason I ask is that although I can get 5 and 30 amp MCBs from tlc,
everywhere else seem to offer 6 and 32 amp.

TIA

Patrick

"Patrick" wrote in message
...
Hi,

Just a quick question;

If I replace my rewirable fuses with plugin mcbs - do I use like for like?
My fuses are 5 amp, 20 amp, and 30 amp. Should I get the same values, or
should I replace the 5 amp with a 6 amp, and the 30 amp with 32 amp?

The reason I ask is that although I can get 5 and 30 amp MCBs from tlc,
everywhere else seem to offer 6 and 32 amp.

TIA

Patrick

I assume your skeleton modular CU system can be changed over from rewireable
fuseholders to MCBs - with a 2-pole isolator and an RCD. Otherwise a new
housing ideally catering for a split load is needed. Regarding32A, note that
electric showers normally consuming 8kW are often protected by the hardier
45A devices.
I think the ratings vary between main manufacturers, but the normal handling
current should be less than its overload tripping sensitivity. Short
circuits tend to approach infinity Amps in 20 milliseconds.
Jim

If I replace my rewirable fuses with plugin mcbs - do I use like for like?
My fuses are 5 amp, 20 amp, and 30 amp. Should I get the same values, or
should I replace the 5 amp with a 6 amp, and the 30 amp with 32 amp?

Normally the 5A/30A MCBs are intended for directly swapping into an old
style fuse box but won't fit a modern consumer unit. The 6A/32A are usually
modern pattern DIN rail types that fit modern consumer units, but can't be
used in an old fuse box.

Christian.

My fuses are 5 amp, 20 amp, and 30 amp. Should I get the same values, or
should I replace the 5 amp with a 6 amp, and the 30 amp with 32 amp?

Normally the 5A/30A MCBs are intended for directly swapping into an old
style fuse box but won't fit a modern consumer unit. The 6A/32A are
usually
modern pattern DIN rail types that fit modern consumer units, but can't be
used in an old fuse box.

Thanks for the replies.

This is a Wylex (grey) fuse box. I do want to upgrade to a new CU split load
CU with mcb and rcd.
As a interim measure until I can afford to replace the the fuse box with a
modern CU I thought I'd replace the rewireable fuse cartridges with Wylex
plug-in MCBs.
The house is about 35-40 years old and this is the original fusebox.

Screwfix sell the Wylex plugins with ratings of 6,16,20,32,40 amps. They
state they are a 'Modern alternative to fuses for Wylex Standard consumer
units' Most places I've found stock this range of ratings.
However tlc stock this range of ratings 5,10,15,20,30,40 amps. They also
state that these are a ' Direct replacement for rewireable and HRC fuse
carriers in the Wylex standard range'.

Patrick wrote:
My fuses are 5 amp, 20 amp, and 30 amp. Should I get the same values, or
should I replace the 5 amp with a 6 amp, and the 30 amp with 32 amp?

Thanks for the replies.

This is a Wylex (grey) fuse box. I do want to upgrade to a new CU split load
CU with mcb and rcd.
As a interim measure until I can afford to replace the the fuse box with a
modern CU I thought I'd replace the rewireable fuse cartridges with Wylex
plug-in MCBs.
The house is about 35-40 years old and this is the original fusebox.

Screwfix sell the Wylex plugins with ratings of 6,16,20,32,40 amps. They
state they are a 'Modern alternative to fuses for Wylex Standard consumer
units' Most places I've found stock this range of ratings.
However tlc stock this range of ratings 5,10,15,20,30,40 amps. They also
state that these are a ' Direct replacement for rewireable and HRC fuse
carriers in the Wylex standard range'.

I'm not sure I see the point for a temporary situation, just replace
the box when you get to that. If you want to spend something on
improving safety, get some non-slip stair strips.

When you pick lighting mcbs, I'd suggest going with 6A type C rather
than the more common type B, as Bs sometimes give a lot of nuisance
trips.


NT

When you pick lighting mcbs, I'd suggest going with 6A type C rather
than the more common type B, as Bs sometimes give a lot of nuisance
trips.

Only if you use dinosaur bulbs.

Christian.

I'm not sure I see the point for a temporary situation, just replace
the box when you get to that. If you want to spend something on
improving safety, get some non-slip stair strips.


This is something I can do now.

I do want to change the box to a modern CU next year, but who knows what is
round the corner - the car might fail its mot, the central heating might
pack in, the dog could get sick. By doing this I'm spending a small amount
of money as a 'temporary' solution, but as we don't know what the year will
bring - 'temporary' might be longer than I'd wish.

I do want to change the box to a modern CU next year, but who knows what
is
round the corner - the car might fail its mot, the central heating might
pack in, the dog could get sick. By doing this I'm spending a small amount
of money as a 'temporary' solution, but as we don't know what the year
will
bring - 'temporary' might be longer than I'd wish.

Then buy anything that fits. The wireable fuses have such poor
characteristics, that a replacement by cartridge fuses or MCBs will easily
meet the requirements, even if the rating is increased, provided the circuit
was already compliant. A 30A rewirable fuse requires either shorter circuits
or thicker cables than a 32A MCB or 30A cartridge fuse.

However,

http://www.screwfix.com/app/sfd/cat/...45666&id=82204

Gives you a split load consumer unit with RCD and 10MCBs for less than 60
quid. Why muck around with a temporary solution? You can do the job properly
first time.

Christian.

of money as a 'temporary' solution, but as we don't know what the year
will
bring - 'temporary' might be longer than I'd wish.

Then buy anything that fits. The wireable fuses have such poor
characteristics, that a replacement by cartridge fuses or MCBs will easily
meet the requirements, even if the rating is increased, provided the
circuit
was already compliant. A 30A rewirable fuse requires either shorter
circuits
or thicker cables than a 32A MCB or 30A cartridge fuse.

However,

http://www.screwfix.com/app/sfd/cat/...45666&id=82204

Gives you a split load consumer unit with RCD and 10MCBs for less than 60
quid. Why muck around with a temporary solution? You can do the job
properly
first time.


Yep agreed. Its not the price of the CU. I'm happy replacing fittings and
have know doubt that I could fit a CU. I don't however feel entirely
comfortable doing it, so it would be the cost of the CU plus the bill from a
pro spark, which I've been led to believe will run into the hundreds.

Yep agreed. Its not the price of the CU. I'm happy replacing fittings and
have know doubt that I could fit a CU. I don't however feel entirely
comfortable doing it, so it would be the cost of the CU plus the bill from
a
pro spark, which I've been led to believe will run into the hundreds.

The job will be not of disimilar magnitude to replacing all the fuseways in
an old fuse box. A bit of extra work to be sure, depending on the available
lengths of cable.

Christian.

"Christian McArdle" wrote in message
...
Yep agreed. Its not the price of the CU. I'm happy replacing fittings and
have know doubt that I could fit a CU. I don't however feel entirely
comfortable doing it, so it would be the cost of the CU plus the bill
from
a
pro spark, which I've been led to believe will run into the hundreds.

The job will be not of disimilar magnitude to replacing all the fuseways
in
an old fuse box. A bit of extra work to be sure, depending on the
available
lengths of cable.

That what worries me. Starting the job only for it to turn into a nightmare.
If I did go for it and all being well, afterwards do I just need to pay the
leccy board to to test it?

That what worries me. Starting the job only for it to turn into a
nightmare.
If I did go for it and all being well, afterwards do I just need to pay
the
leccy board to to test it?

No. You need to pay the local council to test it. Or a qualified
electrician. Unless you happened to do it before the new rules came in.

Christian.

If I did go for it and all being well, afterwards do I just need to pay
the
leccy board to to test it?

No. You need to pay the local council to test it. Or a qualified
electrician. Unless you happened to do it before the new rules came in.

Thanks for that Christian

Christian McArdle wrote:

Yep agreed. Its not the price of the CU. I'm happy replacing fittings and
have know doubt that I could fit a CU. I don't however feel entirely
comfortable doing it, so it would be the cost of the CU plus the bill from

a

pro spark, which I've been led to believe will run into the hundreds.


The job will be not of disimilar magnitude to replacing all the fuseways in
an old fuse box. A bit of extra work to be sure, depending on the available
lengths of cable.

Yup, the rewireable fuse replacement MCBs are not always quite as "plug
in" as the name suggests. Depending on the type and range (and the trip
current) they may come with a new base section which needs to be
substituted for the original base. Installing this can require a certain
amount of reconnecting wires in the CU itself - so if you end up
replacing all of them, it is task not that different from doing the
whole CU from scratch.

--
Cheers,

John.

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On Fri, 16 Dec 2005 19:48:19 +0000, John Rumm
wrote:


Yup, the rewireable fuse replacement MCBs are not always quite as "plug
in" as the name suggests. Depending on the type and range (and the trip
current) they may come with a new base section which needs to be
substituted for the original base. Installing this can require a certain
amount of reconnecting wires in the CU itself - so if you end up
replacing all of them, it is task not that different from doing the
whole CU from scratch.

The replacement "base" for fitting MCBs in a Wylex consumer unit takes
seconds and doesn't need any wires disconnecting - just a little care
if the switch is left "on"...

--
Frank Erskine

Patrick wrote:

I'm not sure I see the point for a temporary situation, just replace
the box when you get to that. If you want to spend something on
improving safety, get some non-slip stair strips.


This is something I can do now.

I do want to change the box to a modern CU next year, but who knows what is
round the corner - the car might fail its mot, the central heating might
pack in, the dog could get sick. By doing this I'm spending a small amount
of money as a 'temporary' solution, but as we don't know what the year will
bring - 'temporary' might be longer than I'd wish.

There isnt a problem to solve Patrick. Wire fuses are legal for new
installs today, and meet all the 16th edn requirements. Theyre 100%
compliant.

MCBs do give faster trips and lower overload margins, but fuses are
nothing to get worried over, as long as some idiot hasnt replaced the
fuse wires with lumps of copper etc. If its a new-to-you house, its
probably worth 50p to replace all the fuse wires with ones you know are
the right rating, as thats where the risk lies with rewirable fuses.

Re who knows whats round the corner, yes, and the one solution to that
is to keep some money in the bank. Wasting it on MCBs youre going to
throw out soon wont achieve a lot imho.

However I do feel from other posts you're being encouraged to do
something thats liable to turn into a nightmare, ie replace your CU
yourself. While it may all go fine, IRL putting in an RCDed CU is a
recipe for trouble, and youre liable to then have to work out why half
of the system wont stay switched on, and then how youre going to keep
the freezer food from spoiling and so on. Just be aware that shared
neutrals, minor leakages and so on, all of which are fairly common,
would cause your new CU to not work. Then you got to find the problem
and sort it.

I'm not against diying it, just I think you need to understand whats
involved and prepare for it, rather than getting dumped in it. If you
do some reading here you should be able to learn what the problems are
and how to sort them so youre upto speed.


NT

wrote:

However I do feel from other posts you're being encouraged to do
something thats liable to turn into a nightmare, ie replace your CU
yourself. While it may all go fine, IRL putting in an RCDed CU is a
recipe for trouble, and youre liable to then have to work out why half
of the system wont stay switched on, and then how youre going to keep
the freezer food from spoiling and so on. Just be aware that shared
neutrals, minor leakages and so on, all of which are fairly common,
would cause your new CU to not work. Then you got to find the problem
and sort it.

I'm not against diying it, just I think you need to understand whats
involved and prepare for it, rather than getting dumped in it. If you
do some reading here you should be able to learn what the problems are
and how to sort them so youre upto speed.

Patrick,

I would tend to agree with most of that. Much depends on what actual
"problem" you are attempting to solve. MCBs are "better" in many cases -
but not necessarily that much so as to offer huge advantages just as a
straight swap for fuses. Including a RCD in at least some circuits has a
bigger implication on overall safety of your system, although there are
both pros and cons. Making sure you have RCD protection for equipment
you use outside however is highly desireable.

You mention that the install as a whole is some 35 to 40 years old -
that may in itself have a much bigger implication on the overall safety
than the type of overcurrent protection used in the CU. At that age
there is a fair chance (unless the system has been widely extended) that
there are insufficent sockets fitted and hence you have to rely on
extension leads etc, and that circuits will not have been designed with
the typical usage of todays homes in mind. There is also the possiblity
that old rubber insulated cable may have been used for some of the
circuits - if so there is a real and present danger posed by this. There
is a fair chance that the main equipotential bonds to the other services
(gas, and water) are missing or undersized.

Knowing what type of earthing arrangement you currently have would also
help your decision making process.

(see the FAQ he

http://www.diyfaq.org.uk/electrical/....html#earthing)



--
Cheers,

John.

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\================================================= ================/

John Rumm wrote:

You mention that the install as a whole is some 35 to 40 years old -
that may in itself have a much bigger implication on the overall safety
than the type of overcurrent protection used in the CU. At that age
there is a fair chance (unless the system has been widely extended) that
there are insufficent sockets fitted and hence you have to rely on
extension leads etc, and that circuits will not have been designed with
the typical usage of todays homes in mind. There is also the possiblity
that old rubber insulated cable may have been used for some of the
circuits - if so there is a real and present danger posed by this. There
is a fair chance that the main equipotential bonds to the other services
(gas, and water) are missing or undersized.

Knowing what type of earthing arrangement you currently have would also
help your decision making process.

(see the FAQ he

http://www.diyfaq.org.uk/electrical/....html#earthing)

I quite agree that the age of the install is the issue there, not its
lack of mcbs. I hadnt really taken in that this was an old rubber
insulated install.

You've likely got a waterpipe earth, and if the supply has ever been
changed to plastic, maybe no earth at all. If its a TT supply and any
connection associatde with the ELCB has come adrift, as I've seen
happen, you may have an earth that will go live at the first low
impedance fault opportunity. I still remember my surprise at being
bitten by what ought to have been earth.

Presumably you've got 2 core cotton rubber pendant flexes, now with
bare live bits at the holders, and maybe very overloaded socket wiring.

Just echoing what John says, that the mcbs arent the issue. Nor is the
CU. Those old Wylexes are basic but adequate.

And nor is replacing the CU a solution. If you fit an RCD'ed CU it
almost certainly will not work, and you'll be stuck with no socket
power until its all rewired.

If it were mine, I'd check the earthing is adequate, inspect and fix
any wiring problems, then leave the whole lot as is until its all
rewired. Then again if its all in rubber, it may be unwise to remove
any socket or switch to check anything, as donig so tends to cause
shorts / fuse pops / fires. It doesnt sound good.

The moral of the tale is tell us what youre trying to achieve in post
1, as often people get the diagnosis or cure wrong, or there are just
better options.

Someone will now tell me I've misunderstood the whole thing probably


NT

wrote:

Patrick wrote:

I'm not sure I see the point for a temporary situation, just replace
the box when you get to that. If you want to spend something on
improving safety, get some non-slip stair strips.


This is something I can do now.

I must admit I'm still running with the 'temporary' solution I put in when I
moved in to my house some ... er ... [mumble] 10 or so years ago and that
was to stick a 30mA RCD between the meter and the CU. (It was made easy in
my case by the installation having a Henley block between the two.) The
only trips I've had have been water getting into electrics e.g. leak from
bathroom into ceiling rose below.

John Stumbles wrote:
wrote:

Patrick wrote:

I'm not sure I see the point for a temporary situation, just replace
the box when you get to that. If you want to spend something on
improving safety, get some non-slip stair strips.


This is something I can do now.

I must admit I'm still running with the 'temporary' solution I put in when I
moved in to my house some ... er ... [mumble] 10 or so years ago and that
was to stick a 30mA RCD between the meter and the CU. (It was made easy in
my case by the installation having a Henley block between the two.) The
only trips I've had have been water getting into electrics e.g. leak from
bathroom into ceiling rose below.

If the OP has a rubber insulated installation, this would probably lose
him all power.

NT

On Sat, 17 Dec 2005 16:06:02 -0800, meow2222 wrote:

If the OP has a rubber insulated installation, this would probably lose
him all power.

IF: the OP said the installation was about 35-40 years old, not that it
was rubber. My parents' house was rewired in the mid-late 60s in PVC.

In article .com,
writes:

If the OP has a rubber insulated installation, this would probably lose
him all power.

Your inference that a rubber installation will be leaking
enough to trip an RCD when it wasn't showing up any faults
without an RCD is rather far-fetched. (Actually, rubber
leaks less than PVC does.)

--
Andrew Gabriel

Andrew Gabriel wrote:

If the OP has a rubber insulated installation, this would probably lose
him all power.

No guarentee that it is rubber at that age, although it is possible -
especially on some of the larger radials.

Your inference that a rubber installation will be leaking
enough to trip an RCD when it wasn't showing up any faults
without an RCD is rather far-fetched. (Actually, rubber
leaks less than PVC does.)

True, although it is rather worse when under any sort of mechanical
stress (conductors tend to work through the insualtion rather more
easily IME).



--
Cheers,

John.

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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

I never even considered that the wiring would be classed as too old for a
modern CU with RCD.

It wouldn't. Any wiring that would trip a 30mA RCD should be condemned as
dangerous. New rubber wiring would have no problem whatsoever passing that
test. The problem is that rubber rots. Its 30 year life span, coupled with
the fact that it was installed more than 50 years ago indicates that much of
the rubber may have perished, leaving it in a dangerously leaky state. The
perishing tends to happen at the ends, where the oxygen can get to it.

Christian.

But my wiring wasn't installed more than 50 years ago, as I said earlier
the
house is about 35-40 years old.

Then it is probably PVC, unless you know otherwise. They haven't decided on
how long PVC lasts. However, 100 years seems reasonable, provided the
circuit is lightly loaded.

Christian.

Patrick wrote:

test. The problem is that rubber rots. Its 30 year life span, coupled with
the fact that it was installed more than 50 years ago indicates that much
of
the rubber may have perished, leaving it in a dangerously leaky state. The


But my wiring wasn't installed more than 50 years ago, as I said earlier the
house is about 35-40 years old.

I think he was explaining what the problem with rubber is - not
suggesting that your house was wired with it. I raised it as a
possibility since I have seen some instalations of that age that did
still have some rubber.

Chances are your house *would* run with an RCD. If you restrict the
number of circuits protected by the RCD to the socket feeding ones only
then you also improve the chances of not having problems (and are also
more compliant with the regs and minimise the dangers of having RCD
protection).

My mums place for example had a full lighting circuit rewire back in the
late 80's but the power circuits are still mostly 60's PVC (with a fair
amount of additional stuff that is newer). There was some rubber on a
few circuits that I had away over the years. At some point it acquired a
"whole house" RCD (when she had a new cloakroom built which had a lekky
shower IIRC), and to be fair has never experienced any spurious trips.

However adding selected RCD protection to some circuits is obviously
harder to retro fit.

I understand the desire to add RCD protection WRT children being in the
house - the same thought crossed my mind. Whilst I felt that we lived
safely here for a good few years with a wylex rewireable CU and whole
house ELCB (TT system), I also knew there was little chance that I or
SWMBO would go sticking metal objects into sockets to see "what would
happen" - whilst I hope the sprogs won't do this I can't guarantee it!

I also had a requirement to add new circuits for which I did not have
sufficient spare ways on the exiting CU (loft conversion), so had to
bite the bullet and go for a big upgrade. The upshot was that I removed
all the old stuff, installed new CUs (five in total!) and RCDs as
required, plus brought all the equipotential and supplementary bonding
up to scratch.

--
Cheers,

John.

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"John Rumm" wrote in message
...
Andrew Gabriel wrote:

If the OP has a rubber insulated installation, this would probably lose
him all power.

No guarentee that it is rubber at that age, although it is possible -
especially on some of the larger radials.

Your inference that a rubber installation will be leaking
enough to trip an RCD when it wasn't showing up any faults
without an RCD is rather far-fetched. (Actually, rubber
leaks less than PVC does.)

True, although it is rather worse when under any sort of mechanical stress
(conductors tend to work through the insulation rather more easily IME).

--
Cheers,

John.
What, rubber-coated in lead sheath? My house's old cables, dissed and
abandoned in situ but replaced by T&E over twenty years ago, just before we
moved in, were worth a bit as scrap when I eventually recovered them!
Jim

Andrew Gabriel wrote:
In article .com,
writes:

re adding a single rcd to what we thought was likely a rubber wired
install:


If the OP has a rubber insulated installation, this would probably lose
him all power.

Your inference that a rubber installation will be leaking
enough to trip an RCD when it wasn't showing up any faults
without an RCD is rather far-fetched. (Actually, rubber
leaks less than PVC does.)

I'm surprised you say that. The old rubber installs I've seen typically
have perished dirty wire ends, and the dirt causes leakage. They also
are prone to having insulation fallen off inside the conduits, again
giving opportunities for leakage. A shared or crossed neutral somewhere
is not uncommon, which will also trip an RCD. Poor neutral to earth
insulation again can cause RCD troubles. Old immersion heaters are
often leaky. Then there are minor faults such as very slight charring
on sockets, poor insulation on various fixtures, etc. Then there are
the appliances, any one or two of which may have enough earth leakage
to trip. None of these will pop a fuse, but they will trip an rcd.


NT

Christian McArdle wrote:
But my wiring wasn't installed more than 50 years ago, as I said earlier
the
house is about 35-40 years old.

Then it is probably PVC, unless you know otherwise. They haven't decided on
how long PVC lasts. However, 100 years seems reasonable, provided the
circuit is lightly loaded.

Christian.

or it might be ashathene, right period for it.

NT

On Mon, 19 Dec 2005 09:54:27 -0000 someone who may be "Patrick"
wrote this:-

I guess what I'll do it fit the plug-in mcbs (there on order
anyway) and leave it at that. If nothing else they will allow my wife to
restore power (if need be) when I'm not at home.

That is one of the few advantages of such things.

Did you order them before asking about them in this group?

The funny thing is, I've been in this house for seven years without any
leccy problems (I have had to rewire a fuse once maybe twice when a 240v
halogen blew), and without even thinking about my fuse box. The thing that
changed is having kids, When I was replacing some socket I thought about
them and how I could make things safer for them.

MCBs will not make things safer for them. Assuming that the circuits
are designed and installed properly, in most circumstances there
will be little change in safety. In a few circumstances safety will
be reduced a bit because of the slow operation of MCBs (it takes a
relatively long time for a mechanism to operate compared to a wire
melting). In a few circumstances safety will be improved a bit,
where an MCB will operate before a rewirable fuse.

The best combination of cost and protection is generally High
Braking Capacity fuses, which are a plug in replacement for your
rewirable fuses. Their only real disadvantage is replacing blown
ones, which means using a screwdriver with some designs of board and
carrier. Resetting an MCB is easier.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

wrote:
Christian McArdle wrote:
But my wiring wasn't installed more than 50 years ago, as I said earlier
the
house is about 35-40 years old.

Then it is probably PVC, unless you know otherwise. They haven't decided on
how long PVC lasts. However, 100 years seems reasonable, provided the
circuit is lightly loaded.

Christian.

or it might be ashathene, right period for it.

I have very early PVC on my upstairs lights. Grey twin core with no
earth strand. House is 1958.

What does this 'ashathene' look like ?

Cheers

Paul

Jim Gregory wrote:

What, rubber-coated in lead sheath?

I have only very rarely seen that. Most of the rubber I have come across
is just plain rubber sheath on both the inners and the outer. Some like
the external downwire that feeds our head end from the aerial power
cable are individually covered PBJ (i.e. jute secondary outside sheath
over the rubber).


--
Cheers,

John.

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In message ,
"Patrick" wrote:

My fuses are 5 amp, 20 amp, and 30 amp. Should I get the same values, or
should I replace the 5 amp with a 6 amp, and the 30 amp with 32 amp?

Normally the 5A/30A MCBs are intended for directly swapping into an old
style fuse box but won't fit a modern consumer unit. The 6A/32A are
usually
modern pattern DIN rail types that fit modern consumer units, but can't be
used in an old fuse box.

Thanks for the replies.

This is a Wylex (grey) fuse box. I do want to upgrade to a new CU split load
CU with mcb and rcd.
As a interim measure until I can afford to replace the the fuse box with a
modern CU I thought I'd replace the rewireable fuse cartridges with Wylex
plug-in MCBs.
The house is about 35-40 years old and this is the original fusebox.

Screwfix sell the Wylex plugins with ratings of 6,16,20,32,40 amps. They
state they are a 'Modern alternative to fuses for Wylex Standard consumer
units' Most places I've found stock this range of ratings.
However tlc stock this range of ratings 5,10,15,20,30,40 amps. They also
state that these are a ' Direct replacement for rewireable and HRC fuse
carriers in the Wylex standard range'.

The Wylex replacements also come with a baseplate. The units have
differently-spaced pins to the rewireables they replace and so they are
not a simple drop-in replacement; you'll need to dismantle the CU. Be
very careful as sometimes the insulation is missing from the meter tail
connections. I believe the 5A/30A variants are designed the same as the
fuse carriers, but I've never used them.

MCBs will be safer than rewireable fuses in practically all
circumstances. In fact if your ring cable is 2.5mm2 with 1mm2 earth
(common in the 1970s and 1980s) then MCBs are definitely preferred.
Modern 2.5/1.5 isn't such a problem.

But since you're looking at Screwfix, why are you worried about
"affording it later"? How many circuits do you have? At £7.25 each, even
a minimal 4-circuit CU is going to cost £29 to upgrade which is
fractionally less than half the cost of Screwfix's Volex 12-way split CU
complete with 63A RCD and 10 varied MCBs and a free pack of screwdrivers
(82204, £58.98).

Remember to notify Building Control before you start - this kind of work
*definitely* comes in as "notifiable" under Part P.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Making sense of technology: http://www.livtech.co.uk/
.... See that buzzer, That's your sound card that is.

Martin Angove wrote:

Remember to notify Building Control before you start - this kind of work
*definitely* comes in as "notifiable" under Part P.

Hwyl!

M.

Wouldnt bco want it tested? A new CU on an old install is then likely
to fail the testing.

As I've said, there may be more to it than meets the eye if the OP
replaces the CU. Given the OP's limited knowledge I would hesitate to
replace it if I were him/her. And the old CU is really not the issue on
a 60s install anyway.


NT

In article .com,
writes:

Wouldnt bco want it tested? A new CU on an old install is then likely
to fail the testing.

As I've said, there may be more to it than meets the eye if the OP
replaces the CU. Given the OP's limited knowledge I would hesitate to
replace it if I were him/her. And the old CU is really not the issue on
a 60s install anyway.

Funny you should say that. When I tested my parents' late 1950's
install in 2000, the Wylex CU was the only faulty item. The ring
circuit fuse carrier had been making a poor contact, resulting in
overheating of the bakalite and insulation melted off the wires.

Since the CU is in the coat cupboard and surrounded by hanging
fabric, I replaced it with a high quality industrial metal
MEMshield2 consumer unit.

--
Andrew Gabriel

In message .com,
wrote:

Martin Angove wrote:

Remember to notify Building Control before you start - this kind of work
*definitely* comes in as "notifiable" under Part P.

Hwyl!

M.

Wouldnt bco want it tested? A new CU on an old install is then likely
to fail the testing.

The whole point of notifying BC is so that they can arrange for it to be
tested. Judging by 1960s-vintage wiring I commonly meet it is likely
that if the system fails inspection it will be down to one of:

* missing cpc on lighting circuits (not universal, but reasonably
common before the mid 1960s)

* main EP bonding not to current regs

* supplementary bonding not present or not to current regs

The lack of RCD protection for sockets likely to feed equipment used
outdoors may also be noted, and supplementary protection on TT systems
(RCD, ELCB or worse) may not be up to scratch.

The 1960s cable I've met tends to be in pretty good nick and easily
passes insulation tests if there is no physical damage. As someone noted
elsewhere we do not have accurate figures for the real lifespan of PVC,
but it certainly outlasts rubber and there are many 40 or 50 year-old
PVC installations out there working perfectly well.


As I've said, there may be more to it than meets the eye if the OP
replaces the CU. Given the OP's limited knowledge I would hesitate to
replace it if I were him/her. And the old CU is really not the issue on
a 60s install anyway.

Having read the whole thread I'd tend to agree that replacing the CU
isn't necessarily the best option for the OP. I'm afraid I was thinking
as "me" and couldn't see the point in spending £30 now for a "temporary"
solution when another £30 would get me a "permanent" one. Although MCBs
are better than rewireables under most circumstances the biggest
"safety" advantage to going the CU route would have to be the
possibility of installing a split unit with RCD.

However, a secondary point I was trying to make (and probably didn't do
so very clearly) was that replacing rewireables with MCBs is (from a
Part P point of view) exactly the same as replacing the whole CU. Anyone
doing so *should* treat the exercise in exactly the same way, satisfy
themselves that cable ratings are not exceeded with the new devices,
upgrade certain parts of the system as required and perform a complete
test.

To be honest, the biggest issue on a 1960s install (apart from the three
mentioned above) is likely to be the sheer lack of sockets. My parents'
house was built in 1967 (IIRC) and is a reasonably large four-bedroom
semi. The downstairs was originally completely open-plan except for the
hall. The kitchen had (again, IIRC) two single sockets and a cooker
point while the whole of the rest of the downstairs had three single
sockets and two fused outlets.

In fact, when my parents moved in, there were only two sockets
downstairs apart from those in the kitchen as the house had been built
without central heating and the previous owners (we moved in in 1972)
had installed a radiator directly covering one of the three sockets.

It's not a simple job to add more either, as the single "ring" is run
under the floor upstairs, and the sockets downstairs are *spurs*.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Making sense of technology: http://www.livtech.co.uk/
.... I want everything; do you have it??

Martin Angove wrote:
In message .com,
wrote:

Martin Angove wrote:

Remember to notify Building Control before you start - this kind of work
*definitely* comes in as "notifiable" under Part P.

Hwyl!

M.

Wouldnt bco want it tested? A new CU on an old install is then likely
to fail the testing.

The whole point of notifying BC is so that they can arrange for it to be
tested. Judging by 1960s-vintage wiring I commonly meet it is likely
that if the system fails inspection it will be down to one of:

* missing cpc on lighting circuits (not universal, but reasonably
common before the mid 1960s)

* main EP bonding not to current regs

* supplementary bonding not present or not to current regs

The lack of RCD protection for sockets likely to feed equipment used
outdoors may also be noted, and supplementary protection on TT systems
(RCD, ELCB or worse) may not be up to scratch.

The 1960s cable I've met tends to be in pretty good nick and easily
passes insulation tests if there is no physical damage. As someone noted
elsewhere we do not have accurate figures for the real lifespan of PVC,
but it certainly outlasts rubber and there are many 40 or 50 year-old
PVC installations out there working perfectly well.


As I've said, there may be more to it than meets the eye if the OP
replaces the CU. Given the OP's limited knowledge I would hesitate to
replace it if I were him/her. And the old CU is really not the issue on
a 60s install anyway.

Having read the whole thread I'd tend to agree that replacing the CU
isn't necessarily the best option for the OP. I'm afraid I was thinking
as "me" and couldn't see the point in spending £30 now for a "temporary"
solution when another £30 would get me a "permanent" one. Although MCBs
are better than rewireables under most circumstances the biggest
"safety" advantage to going the CU route would have to be the
possibility of installing a split unit with RCD.

However, a secondary point I was trying to make (and probably didn't do
so very clearly) was that replacing rewireables with MCBs is (from a
Part P point of view) exactly the same as replacing the whole CU. Anyone
doing so *should* treat the exercise in exactly the same way, satisfy
themselves that cable ratings are not exceeded with the new devices,
upgrade certain parts of the system as required and perform a complete
test.

To be honest, the biggest issue on a 1960s install (apart from the three
mentioned above) is likely to be the sheer lack of sockets. My parents'
house was built in 1967 (IIRC) and is a reasonably large four-bedroom
semi. The downstairs was originally completely open-plan except for the
hall. The kitchen had (again, IIRC) two single sockets and a cooker
point while the whole of the rest of the downstairs had three single
sockets and two fused outlets.

In fact, when my parents moved in, there were only two sockets
downstairs apart from those in the kitchen as the house had been built
without central heating and the previous owners (we moved in in 1972)
had installed a radiator directly covering one of the three sockets.

It's not a simple job to add more either, as the single "ring" is run
under the floor upstairs, and the sockets downstairs are *spurs*.

Hwyl!

M.

What also strikes me as a problem with any old install is that more
often than not they've been aded to at various times, frequently by
people with insufficient knowledge to do it porperly. You wont find
many people continuing today to live with those sort of socket numbers.


NT

Hi just to follow up.

The MCBs are now installed. No re-wiring of the CU involved. Simply unscrew
the base of the rewirable and then screw the new base in and the plug the
mcb in.
As mentioned in this thread - even though tlc list 5 amp and 30 amp mcbs
they do actually provide 6 amp and 32 amp. Once they were installed I simply
broke the 'knockout' from the cover to allow it to act as a collar for the
deeper mcbs.
If nothing else they will allow the wife to restore power if need be when
I'm away on business.

On the same note it would appear that my wiring would in theory but up to
modern CU mcb/rcd standards. My sister lives in the same style/age of house
a couple of streets down from me. Hers is rented from the local authority
and two years back they removed all original fuse boxes and fitted split
load mcb/rcd CUs. She has not experienced any spurious trips.

Thanks again to all who replied - it was most appreciated. Re reading them
its clear there are conflicting views on the subject.

--
Patrick