Replacing fuses with MCB's
 

My 25 year old MEM consumer fuse box is still in A1 condition and I've
only had two fuses blow during that peiod. However I do feel I ought
to update and fit some MCB's.

My MEM fuses screw onto the live buss bar and the other side of the
fuse takes the wire for the ring main or whatever.

Can I replace these fuses directly with a screw on MCB like say this
from ScrewFix...
MK 16A SP Type B MCB 6kA

....or do I have to replace the consumer box to one that just has a clip
on supporting rail with the supply main wire going in one side of the
MCB and the ring main wire into the output side.

T I A Chris.

Replacing fuses with MCB's
 

wrote:

My 25 year old MEM consumer fuse box is still in A1 condition and I've
only had two fuses blow during that peiod. However I do feel I ought
to update and fit some MCB's.

My MEM fuses screw onto the live buss bar and the other side of the
fuse takes the wire for the ring main or whatever.

Can I replace these fuses directly with a screw on MCB like say this
from ScrewFix...
MK 16A SP Type B MCB 6kA

First question is: what problem are you trying to fix? Does your
existing CU have rewireable fuses or cartridge fuses?

...or do I have to replace the consumer box to one that just has a clip
on supporting rail with the supply main wire going in one side of the
MCB and the ring main wire into the output side.

Most modern CUs have a busbar that connects to the base of all the MCBs
rather than a wire as such. The top circuit connections being made to
the top of each MCB.

--
Cheers,

John.

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

Replacing fuses with MCB's
 

First question is: what problem are you trying to fix? Does your
existing CU have rewireable fuses or cartridge fuses?

I do NOT have a problem. I just wish to upgrade from fuses to MCBs.
My fuses are rewireable types.

The pictures I've seen of MCBs seem to just clip onto a support bar and
have a screw terminal at each side for wires. If they screw to a buss
bar I'd only expect to see one screw terminal for the output to the
ring or spur or whatever.

Chris.

Chris.

Replacing fuses with MCB's
 

You'll be lucky to find a compatible MCB for such an old unit. HAs the
unit got a 'smoked grey perspex cover' on it? if so, are the 'prongs'
on the fuse carriers oriented side to side or are they top to bottom?


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

Replacing fuses with MCB's
 

In message .com,
writes

The pictures I've seen of MCBs seem to just clip onto a support bar and
have a screw terminal at each side for wires. If they screw to a buss
bar I'd only expect to see one screw terminal for the output to the
ring or spur or whatever.


No, one of the screws is for fixing the MCB in place on the bus bar, and
presumably ensuring good electrical connection.
--
Chris French

Replacing fuses with MCB's
 

On 17 Jan 2006 13:54:14 -0800 someone who may be
wrote this:-

The pictures I've seen of MCBs seem to just clip onto a support bar and
have a screw terminal at each side for wires. If they screw to a buss
bar I'd only expect to see one screw terminal for the output to the
ring or spur or whatever.

While there is a copper busbar in consumer units, MCBs have a screw
terminal at each side. One terminal is screwed onto the busbar, the
other takes the circuit wires. The module clips onto a rail, but the
electrical connections are made by screw terminals.

I suspect that a unit that old will not take modern MCBs and MEM
don't have any replacements available (check with their web site for
what is currently available). Should you wish to replace your
existing rewirable fuses, you will need to replace the whole
consumer unit. Personally I would not do this unless there were
pressing reasons, like a need for extra circuits or something like
old age making rewiring fuses more difficult. More importantly, the
existing wiring should be tested, using the right equipment, to make
sure it is still sound.


--
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

Replacing fuses with MCB's
 

wrote:

First question is: what problem are you trying to fix? Does your

existing CU have rewireable fuses or cartridge fuses?

I do NOT have a problem. I just wish to upgrade from fuses to MCBs.
My fuses are rewireable types.

MCBs do offer greater ease of use, however if you are not having to
rewire fuses on a regular basis then there is only a limited amount to
gained from the change. MCBs represent slightly better protection in
most cases, but not that much in absolute terms assuming the wiring is
in a reasonable state (rewireable fuses are still permitted in the
current wiring regs). If you are looking to improve safety then you may
get more "bang for your buck" making sure you have RCD protection where
it will give best advantage.

The pictures I've seen of MCBs seem to just clip onto a support bar and
have a screw terminal at each side for wires. If they screw to a buss
bar I'd only expect to see one screw terminal for the output to the
ring or spur or whatever.

There are not usually any side connections on MCBs

Take as an example:

http://www.tlc-direct.co.uk/Products/CM7106B.html

The bottom screw and terminal is used to secure the MCB to the busbar.

A busbar is usually comb like:

http://www.tlc-direct.co.uk/Products/MK5590.html

The prongs of the bar poke into the bottom terminal of the MCB and the
screw is done up. The end prog of the bar pokes into the bottom terminal
of an incomer switch or RCD which is fed from the meter tails which fix
into the top connection.

The rear of it clips to the DIN rail, and the top screw is used to clamp
the wires to the circuit.


--
Cheers,

John.

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

Replacing fuses with MCB's
 

There are not usually any side connections on MCBs
Take as an example:
http://www.tlc-direct.co.uk/Products/CM7106B.html
The bottom screw and terminal is used to secure the MCB to the busbar.
A busbar is usually comb like:
http://www.tlc-direct.co.uk/Products/MK5590.html

Ah! The buss bar has prongs, I see now. Thanks fot the picture.

The wiring is only 25 years old and done with all the same wire type as
today. As I said I've only had two/three fuse blow in 25 years, one
self inflicted, one due to a mouse and one due to a light bulb blowing.

The CU does have the two smoked perspex drop down windows that give
access to the 12 fuses. About five years ago I did tidy it all up when
I inserted a new ring main in a new bedroom and replaced the above
mouse bitten cable.

The only reason for replacing the fuses with MCBs was to make it a bit
more up to date so that if I did sell up the next person wouldn't have
to call out a Lektrishun to replace a fuse.

Chris.

Replacing fuses with MCB's
 

Replacing fuses with MCB's
 

wrote:

The only reason for replacing the fuses with MCBs was to make it a bit
more up to date so that if I did sell up the next person wouldn't have
to call out a Lektrishun to replace a fuse.

I would have thought if you were going to replace it, it would only be
worth doing if you were going to upgrade the whole thing so that you
could have some form of split load affair to give you RCD protection on
sockets etc, and to make sure all the equipotential bonding is up to
scratch (since you can almost guarantee that will be a comment on a
survey if not to current standards). You make life much simpler with
obtaining suitable MCBs etc if you choose a current model of CU rather
than sticking with one that uses bespoke parts that may be in short supply.

It would give you the chance to split existing circuits or add new ones
where appropriate (like a dedicated ring circuit for the kitchen perhaps)

You could also design in a few extra nice touches like battery
maintained emergency light close to the CU that is powered from the same
MCB as the lighting circuit that usually illuminates the CU - that way
if the circuit trips you can still see what you are doing to reset it.

--
Cheers,

John.

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

Replacing fuses with MCB's
 

On Wed, 18 Jan 2006 12:17:38 +0000 someone who may be John Rumm
wrote this:-

You could also design in a few extra nice touches like battery
maintained emergency light close to the CU that is powered from the same
MCB as the lighting circuit that usually illuminates the CU - that way
if the circuit trips you can still see what you are doing to reset it.

Alternatively just wire a suitable light to another lighting
circuit. Other than a major failure, this will allow one to sort out
most problems without a torch.


--
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

Replacing fuses with MCB's
 

On Tue, 17 Jan 2006 23:11:07 +0000, John Rumm
wrote:

(rewireable fuses are still permitted in the
current wiring regs).

So I can still do /some/ re-wiring affecting the kitchen, bathroom...


Geo

Replacing fuses with MCB's
 

Geo wrote:

(rewireable fuses are still permitted in the
current wiring regs).


So I can still do /some/ re-wiring affecting the kitchen, bathroom...

Not quite sure how you arrive at that statement from my comment about
fuses... ;-)

I take it you are refering to Part Pee rather than the wiring regs
(BS7671)...

Regarding part P, you can do any rewiring you like in any location. You
can also do it legally if you are prepared to involve building control
at the relevant times.

--
Cheers,

John.

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

Replacing fuses with MCB's
 

On Wed, 18 Jan 2006 15:58:51 +0000, John Rumm
wrote:

Geo wrote:

So I can still do /some/ re-wiring affecting the kitchen, bathroom...

Not quite sure how you arrive at that statement from my comment about
fuses... ;-)

I take it you are refering to Part Pee rather than the wiring regs
(BS7671)...

Regarding part P, you can do any rewiring you like in any location. You
can also do it legally if you are prepared to involve building control
at the relevant times.

Referring to re-wiring my fuses - there is a wee card with the spare wire
wrapped round it on top of the fuse-box. Only used it 30 years ago when some
idiot turned on too many lights while the (750w) infrared bathroom dimplex was
switched on :-)

Geo

Replacing fuses with MCB's
 

On Wed, 18 Jan 2006 16:41:39 GMT someone who may be Geo
wrote this:-

Referring to re-wiring my fuses - there is a wee card with the spare wire
wrapped round it on top of the fuse-box. Only used it 30 years ago when some
idiot turned on too many lights while the (750w) infrared bathroom dimplex was
switched on :-)

The heater should really be on a spur off the ring main. Then the
problem would not arise.



--
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

Replacing fuses with MCB's
 

On Wed, 18 Jan 2006 18:35:53 +0000, David Hansen
wrote:

On Wed, 18 Jan 2006 16:41:39 GMT someone who may be Geo
wrote this:-

Referring to re-wiring my fuses - there is a wee card with the spare wire
wrapped round it on top of the fuse-box. Only used it 30 years ago when some
idiot turned on too many lights while the (750w) infrared bathroom dimplex was
switched on :-)

The heater should really be on a spur off the ring main. Then the
problem would not arise.

It was dumped in '79 when I installed the central heating.

BTW they were also sold as bathroom lamp fittings.

Geo

Replacing fuses with MCB's
 

On Wed, 18 Jan 2006 20:22:18 GMT someone who may be Geo
wrote this:-

[(750w) infrared bathroom dimplex]

It was dumped in '79 when I installed the central heating.

They still have their uses, when it is not worth having central
heating on. In spring and autumn for example.

BTW they were also sold as bathroom lamp fittings.

They were but, like heat lamps, should not be wired into lighting
circuits. Rather they should be on a (fused) spur from a ring main.


--
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

Replacing fuses with MCB's
 

See below:

wrote in message
oups.com...
My 25 year old MEM consumer fuse box is still in A1 condition and I've
only had two fuses blow during that peiod. However I do feel I ought
to update and fit some MCB's.

My MEM fuses screw onto the live buss bar and the other side of the
fuse takes the wire for the ring main or whatever.

Can I replace these fuses directly with a screw on MCB like say this
from ScrewFix...
MK 16A SP Type B MCB 6kA

...or do I have to replace the consumer box to one that just has a clip
on supporting rail with the supply main wire going in one side of the
MCB and the ring main wire into the output side.

T I A Chris.


I found some MCBs in FADS about a year ago that had bayonets on them and
simply plugged in in place of the old rewirable fuse holders. Cost about £15
each and available in a range of ratings. I had to modify the plastic cover
on the CU cos they stick out more than the old fuses, but easily done with a
small saw and knife. If you have trouble finding them let me know and I'll
take one out and get the manufactures name (if it's printed on there).
Much more convenient if a bulb blowing causes the fuse to go, as was
happening to me.
David
(remove _notme to email)

Replacing fuses with MCB's
 

See below:

wrote in message
oups.com...
My 25 year old MEM consumer fuse box is still in A1 condition and I've
only had two fuses blow during that peiod. However I do feel I ought
to update and fit some MCB's.

My MEM fuses screw onto the live buss bar and the other side of the
fuse takes the wire for the ring main or whatever.

Can I replace these fuses directly with a screw on MCB like say this
from ScrewFix...
MK 16A SP Type B MCB 6kA

...or do I have to replace the consumer box to one that just has a clip
on supporting rail with the supply main wire going in one side of the
MCB and the ring main wire into the output side.

T I A Chris.


I found some MCBs in FADS about a year ago that had bayonets on them and
simply plugged in in place of the old rewirable fuse holders. Cost about £15
each and available in a range of ratings. I had to modify the plastic cover
on the CU cos they stick out more than the old fuses, but easily done with a
small saw and knife. If you have trouble finding them let me know and I'll
take one out and get the manufactures name (if it's printed on there).
Much more convenient if a bulb blowing causes the fuse to go, as was
happening to me.
David
(remove _notme to email)

Replacing fuses with MCB's
 

On Fri, 20 Jan 2006 10:19:00 GMT, "DavidM"
wrote:

See below:

wrote in message
roups.com...
My 25 year old MEM consumer fuse box is still in A1 condition and I've
only had two fuses blow during that peiod. However I do feel I ought
to update and fit some MCB's.

My MEM fuses screw onto the live buss bar and the other side of the
fuse takes the wire for the ring main or whatever.

Can I replace these fuses directly with a screw on MCB like say this
from ScrewFix...
MK 16A SP Type B MCB 6kA

...or do I have to replace the consumer box to one that just has a clip
on supporting rail with the supply main wire going in one side of the
MCB and the ring main wire into the output side.

T I A Chris.


I found some MCBs in FADS about a year ago that had bayonets on them and
simply plugged in in place of the old rewirable fuse holders. Cost about £15
each and available in a range of ratings. I had to modify the plastic cover
on the CU cos they stick out more than the old fuses, but easily done with a
small saw and knife. If you have trouble finding them let me know and I'll
take one out and get the manufactures name (if it's printed on there).
Much more convenient if a bulb blowing causes the fuse to go, as was
happening to me.
David
(remove _notme to email)

Same problem here with the screwfix ones.

Replacing fuses with MCB's
 

DavidM wrote:

I found some MCBs in FADS about a year ago that had bayonets on them and
simply plugged in in place of the old rewirable fuse holders. Cost about ï½£15
each and available in a range of ratings. I had to modify the plastic cover


At that price you could replace the whole CU with a modern split load
one including MCBs etc using one of the various special bundle deals
that screwfix et al do.

--
Cheers,

John.

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

Replacing fuses with MCB's