Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Is this just because modern wiring is so much more "safe" than once
was the case? This house was built in 2004.

MM

MM wrote:
Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Is this just because modern wiring is so much more "safe" than once
was the case? This house was built in 2004.

MM

I suspect you don't mean earth leakage trips..its uncommon to have those
on lighting circuits alone..

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

RCD's can also trip if they are marginal, and there is a lot
ofcapaicatbce between live or neutral and ground..

I suspect you don't mean earth leakage trips..its uncommon to have those
on lighting circuits alone..

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

Out of interest, how do they specify slower acting ones ? I've never
seen them, but then for a twice-a-year event (the MCB tripping on bulb
blowing) I also fall into the CBA category ...

In article ,
MM wrote:
Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Are you sure you mean ELCB? It would be an unusual domestic installation
which had these on individual lighting circuits. Sure you don't mean MCB?

Is this just because modern wiring is so much more "safe" than once
was the case? This house was built in 2004.

Standard MCBs trip in a shorter time than a wire fuse takes to blow, and
bulbs often draw excessive current at the instant when they blow. Plenty
of theories on why - you'd probably find them by Googling.

--
*Pride is what we have. Vanity is what others have.

Dave Plowman London SW
To e-mail, change noise into sound.

The message
from The Natural Philosopher contains these words:

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

They also are supposed to have fast-blow fuses inside each bulb these
days to stop this happening. Does it? Does it hell!

--
Skipweasel
Pay no attention to that man behind the curtain.

wrote:

I suspect you don't mean earth leakage trips..its uncommon to have those
on lighting circuits alone..

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

Out of interest, how do they specify slower acting ones ? I've never
seen them, but then for a twice-a-year event (the MCB tripping on bulb
blowing) I also fall into the CBA category ...

Type C instead of te more common type B. A bit less prone to nuisance
trips.

NT

wrote:
wrote:

I suspect you don't mean earth leakage trips..its uncommon to have those
on lighting circuits alone..

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

Out of interest, how do they specify slower acting ones ? I've never
seen them, but then for a twice-a-year event (the MCB tripping on bulb
blowing) I also fall into the CBA category ...

Type C instead of te more common type B. A bit less prone to nuisance
trips.

AIUI though, the reason for the trip is just before the filament blows,
an arc is created, which has a very low (almost infintesimal)
resistance which leads to the current draw being astronomical (almost
infinite) certainly in excess of 200A.

It's the speed that the MCB reacts with that causes the trip. I would
have though that even a type C would trip when a bulb blew ?

The message .com
from contains these words:

AIUI though, the reason for the trip is just before the filament blows,
an arc is created, which has a very low (almost infintesimal)
resistance which leads to the current draw being astronomical (almost
infinite) certainly in excess of 200A.

Just after, surely? While the filament's still intact there's little
localised potential difference from which to strike an arc.

As I understand it, as the break opens a small spark starts - easy
enough to do as the gas in the bulb is already hot as is the filament -
and the arc being very low impedance and most imporantly /mobile/ is
able to run along the filaments towards the leadwires introducing what
is damned nearly a dead short.

--
Skipweasel
Pay no attention to that man behind the curtain.

Guy King wrote:
The message .com
from contains these words:

AIUI though, the reason for the trip is just before the filament blows,
an arc is created, which has a very low (almost infintesimal)
resistance which leads to the current draw being astronomical (almost
infinite) certainly in excess of 200A.

Just after, surely? While the filament's still intact there's little
localised potential difference from which to strike an arc.

As I understand it, as the break opens a small spark starts - easy
enough to do as the gas in the bulb is already hot as is the filament -
and the arc being very low impedance and most imporantly /mobile/ is
able to run along the filaments towards the leadwires introducing what
is damned nearly a dead short.

A better description than mine ! Anyway, the point is that for a split
second the current draw is trying to climb to infinity. So irrespective
of the *current* tolerance on the MCB, it would still trip.

Really I need to get one which only trips if the current drawn exceeds
the limit for (say) more than a millisecond or two.

Guy King wrote:
The message
from The Natural Philosopher contains these words:

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

They also are supposed to have fast-blow fuses inside each bulb these
days to stop this happening. Does it? Does it hell!

Not all do. Candle bulbs are the worst offenders..

Guy King wrote:
The message .com
from contains these words:

AIUI though, the reason for the trip is just before the filament blows,
an arc is created, which has a very low (almost infintesimal)
resistance which leads to the current draw being astronomical (almost
infinite) certainly in excess of 200A.

Just after, surely? While the filament's still intact there's little
localised potential difference from which to strike an arc.

As I understand it, as the break opens a small spark starts - easy
enough to do as the gas in the bulb is already hot as is the filament -
and the arc being very low impedance and most imporantly /mobile/ is
able to run along the filaments towards the leadwires introducing what
is damned nearly a dead short.

That's my understanding, more or less.

MM wrote:
Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Is this just because modern wiring is so much more "safe" than once
was the case? This house was built in 2004.

MM

Like the rest I reckon you've got ELCB's and MCB's muddled. If the
ELCB went then the whole house would in all likelihood go down. As
you've got a modern house I suspect you will have a split consumer unit
in which the lights are NOT off the ELCB so that if an earth leakage
occurs in an item on the power circuits and does trip the ELCB, then
the lights will remain on.

Having said all, thanks for asking the question as I've recently done a
CU replacement and was heading towards asking the same one due to the
nuisance trips when a bulb fused. I'm surprised at one contributor who
reckoned he only got 1 or 2 a year - he must buy better quality
filament bulbs than me as I get one every couple of months.

Rob

On Tue, 12 Dec 2006 11:20:13 +0000, The Natural Philosopher
wrote:

MM wrote:
Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Is this just because modern wiring is so much more "safe" than once
was the case? This house was built in 2004.

MM

I suspect you don't mean earth leakage trips..its uncommon to have those
on lighting circuits alone..

I mean the switches in place of the fuses of yore. My consumer unit
contains a whole row of them. Mostly black, some red.

MM

On 12 Dec 2006 04:57:17 -0800, wrote:

I suspect you don't mean earth leakage trips..its uncommon to have those
on lighting circuits alone..

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

Out of interest, how do they specify slower acting ones ? I've never
seen them, but then for a twice-a-year event (the MCB tripping on bulb
blowing) I also fall into the CBA category ...

Seems like CBA applies to me, too! When the bulb went late last night,
I'd already switched on the bedside light, so I thought, stuff it, I'm
not going to grope my way down to the kitchen now, find the torch,
open the inner garage door, get the stepladder and clamber up to the
consumer unit.

I didn't actually get round to flicking the switch back up until about
9 a.m. this morning.

MM

On 12 Dec 2006 08:17:53 -0800, wrote:


Guy King wrote:
The message .com
from contains these words:

AIUI though, the reason for the trip is just before the filament blows,
an arc is created, which has a very low (almost infintesimal)
resistance which leads to the current draw being astronomical (almost
infinite) certainly in excess of 200A.

Just after, surely? While the filament's still intact there's little
localised potential difference from which to strike an arc.

As I understand it, as the break opens a small spark starts - easy
enough to do as the gas in the bulb is already hot as is the filament -
and the arc being very low impedance and most imporantly /mobile/ is
able to run along the filaments towards the leadwires introducing what
is damned nearly a dead short.

A better description than mine ! Anyway, the point is that for a split
second the current draw is trying to climb to infinity. So irrespective
of the *current* tolerance on the MCB, it would still trip.

Really I need to get one which only trips if the current drawn exceeds
the limit for (say) more than a millisecond or two.

In my house the switch doesn't /always/ trip. Just mostly.

MM

On Tue, 12 Dec 2006 13:25:17 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
MM wrote:
Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Are you sure you mean ELCB? It would be an unusual domestic installation
which had these on individual lighting circuits. Sure you don't mean MCB?

Yeah, probably I do! I just mean the switches fitted as standard
nowadays where my old 1947 council house had push-in fuse holders.

MM

On 12 Dec 2006 08:52:39 -0800, "robgraham"
wrote:


MM wrote:
Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Is this just because modern wiring is so much more "safe" than once
was the case? This house was built in 2004.

MM

Like the rest I reckon you've got ELCB's and MCB's muddled. If the
ELCB went then the whole house would in all likelihood go down. As
you've got a modern house I suspect you will have a split consumer unit
in which the lights are NOT off the ELCB so that if an earth leakage
occurs in an item on the power circuits and does trip the ELCB, then
the lights will remain on.

Having said all, thanks for asking the question as I've recently done a
CU replacement and was heading towards asking the same one due to the
nuisance trips when a bulb fused. I'm surprised at one contributor who
reckoned he only got 1 or 2 a year - he must buy better quality
filament bulbs than me as I get one every couple of months.

Well, I only buy the cheapest bulbs, Tesco's or ASDA's Smart Price
brand. They seem to last as long as any other and are dirt cheap. I
reckon I replace two or three a year, tops. Most bedrooms, however,
never have them switched on from one month to the next.

MM

The message
from The Natural Philosopher contains these words:

internal fuses
Not all do. Candle bulbs are the worst offenders..

Don't have any handy to peep at.

--
Skipweasel
Pay no attention to that man behind the curtain.

On 12 Dec 2006 08:17:53 -0800 someone who may be
wrote this:-

A better description than mine ! Anyway, the point is that for a split
second the current draw is trying to climb to infinity. So irrespective
of the *current* tolerance on the MCB, it would still trip.

Only if the MCB trips instantly. However, no circuit breaker
operates instantly, for the rather obvious reason that there are a
number of mechanical bits and pieces which need to move before the
circuit is opened.


--
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

On Tue, 12 Dec 2006 13:25:17 +0000 (GMT) someone who may be "Dave
Plowman (News)" wrote this:-

Standard MCBs trip in a shorter time than a wire fuse takes to blow,

That rather depends on the situation.




--
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:

Really I need to get one which only trips if the current drawn exceeds
the limit for (say) more than a millisecond or two.

Its called a fuse! ;-)

--
Cheers,

John.

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

The message
from contains these words:

This used to happen /many/ years ago with fuses. Then they came along with
bulbs that had a built in fuse to prevent this happening.

Well, the incandescent bulbs[1] we use here appear to have fuses in and
it still happens - so do you have another explanation? I suspect the
fuse still doesn't react as fast as the MCB.

[1]I think we've got two left - apart from those in the cooker hood. Got
several live spares in the cupboard though.

--
Skipweasel
Pay no attention to that man behind the curtain.

wrote:
I suspect you don't mean earth leakage trips..its uncommon to have those
on lighting circuits alone..

Yes, its very common for bulbs to trip a standard MCB.. as they arc on
failure and draw quite large currents before burning out. Mine do it
every time..I s'pose I could replace then with slower acting ones..but I
can't be arsed..

Out of interest, how do they specify slower acting ones ? I've never
seen them, but then for a twice-a-year event (the MCB tripping on bulb
blowing) I also fall into the CBA category ...

You can get a pack of 10 lithium coin cell powered LED torches, from ebay,
for a couple of quid.

Scattering these round the house so that you've always got one to hand
if the power goes out can help.

Personally - as part of the rewiring effort, I'm putting in a single LED
uplighter per room.
(single 5mm LED)
These go on when the power goes off, for whatever reason.

On Wed, 13 Dec 2006 12:47:21 GMT someone who may be Guy King
wrote this:-

I suspect the
fuse still doesn't react as fast as the MCB.

Do you? Why?

A generalisation is that a fuse reacts much faster than an MCB
during a high current fault, but an MCB reacts faster than a fuse
during a low current fault (an overload).


--
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

The message
from David Hansen contains these words:

I suspect the fuse still doesn't react as fast as the MCB.

Do you? Why?

Because when the lamp blows it still takes out the MCB even when there's
an internal fuse. For all your cunning reasoning, real life experience
suggests that having a fuse in the bulb doesn't prevent the breaker
breaking.

--
Skipweasel
Pay no attention to that man behind the curtain.

On Wed, 13 Dec 2006 18:49:50 GMT someone who may be Guy King
wrote this:-

Because when the lamp blows it still takes out the MCB even when there's
an internal fuse.

As others have said, fuses (in consumer units) can also be "taken
out" in such circumstances.

For all your cunning reasoning, real life experience
suggests that having a fuse in the bulb doesn't prevent the breaker
breaking.

I made no comment on fuses in bulbs. The comparison is between fuses
in consumer units and MCBs in consumer units.


--
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

The message
from David Hansen contains these words:

Because when the lamp blows it still takes out the MCB even when there's
an internal fuse.

As others have said, fuses (in consumer units) can also be "taken
out" in such circumstances.

For all your cunning reasoning, real life experience
suggests that having a fuse in the bulb doesn't prevent the breaker
breaking.

I made no comment on fuses in bulbs. The comparison is between fuses
in consumer units and MCBs in consumer units.

Sorry, I thought you were saying that MCBs no longer pop when a light
bulb blows because bulbs now have fuses.

I was actually answering "B Thumbs" who said in reply to me saying that
blowing bulbs take out MCBs "This used to happen /many/ years ago with
fuses. Then they came along with bulbs that had a built in fuse to
prevent this happening. Do incandescent lamps no longer incorporate a
fuse, or is it just the halogen ones?"

So my reply /was/ about bulbs with fuses though it may not have been
aimed at you.

--
Skipweasel
Pay no attention to that man behind the curtain.

In article ,
David Hansen writes:
On Wed, 13 Dec 2006 12:47:21 GMT someone who may be Guy King
wrote this:-

I suspect the
fuse still doesn't react as fast as the MCB.

Do you? Why?

A generalisation is that a fuse reacts much faster than an MCB
during a high current fault, but an MCB reacts faster than a fuse
during a low current fault (an overload).

Hum,
It's sufficiently more complex than that I don't think any
such generalisation can be valid (and if you look at the trip
curves, _in general_ I would say it's the other way around).
For example, what to you mean by "react"? Actually detect
the error condition, or finish clearing the error condition,
because those two are quite different between MCBs and fuses,
and even quite different between different types of fuses.

Lamp base fuses seem mostly to be of the bare wire type, which
are going to be similar response to a BS3036 semi-enclosed
(a.k.a rewirable) fuse. Occasionally, ballotini fuses are used,
which have different error detection and clearing times, more
like that of a cartridge fuse.

Once an open wire fuse melts, it can take a number of mains
cycles before the vapour has dispersed sufficiently for the
arc to be quenched. Meanwhile, an MCB can operate in less than
a half cycle, whilst the fuse arc is still running. If you look
at a lamp which has tripped an MCB, you will see its fuses are
blown, but they were unable to quench the arc before the MCB
tripped. It's a case of a current which grossly exceeds both
the fault current ratings of both protective devices, and they
both trip. I've never seen a lamp with fuses trip an MCB without
also blowing its lamp base fuses (both of them if is has two).

--
Andrew Gabriel

On 14 Dec 2006 08:45:34 GMT someone who may be
(Andrew Gabriel) wrote this:-

A generalisation is that a fuse reacts much faster than an MCB
during a high current fault, but an MCB reacts faster than a fuse
during a low current fault (an overload).

It's sufficiently more complex than that I don't think any
such generalisation can be valid

I remain happy with that generalisation.

(and if you look at the trip
curves, _in general_ I would say it's the other way around).

At the risk of starting a, "mine is bigger then yours", discussion,
not something I am keen on. There is a saying, if you think you
understand something then try writing computer software to model it.
If the software works then you really do understand the subject. I
have written and maintained computer software to model electrical
devices, though only up to 33kV.

Once an open wire fuse melts,

I didn't once mention a rewirable fuse.


--
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

On Thu, 14 Dec 2006 21:08:10 +0000, David Hansen wrote:

There is a saying, if you think you
understand something then try writing computer software to model it.
If the software works then you really do understand the subject.

That's ********. I've written several computer models, all of them modeling
with varying degrees of accuracy systems of assorted complexities. I can't
pretend to have understood the subject well for every model.

And no, I wasn't coding someone else's models.

David Hansen wrote:

At the risk of starting a, "mine is bigger then yours", discussion,
not something I am keen on. There is a saying, if you think you
understand something then try writing computer software to model it.
If the software works then you really do understand the subject.

The principles here are fairly straightforward, it's obtaining and
applying the relevant data that's the problem.

At a particular fault current:

(i) if the operating I^2*t of the MCB is less than the pre-arcing
I^2*t of the fuse then the MCB will discriminate in favour of
the fuse (i.e. breaker trips, fuse does not blow);

(ii) if the operating I^2*t of the MCB exceeds the total clearing
I^2*t of the fuse (pre-arcing and arcing) then the fuse will
discriminate in favour of the MCB (fuse blows, breaker does
not trip);

(iii) if the operating I^2*t of the MCB exceeds the pre-arcing I^2*t
of the fuse, but does not exceed its total clearing I^2*t then
both devices will operate (no discrimination, fuse element melts
but the arc is extinguished by the MCB).

Now all you need is the relevant I^2*t curves and knowledge of the fault
level. I^2*t data for MCBs should be fairly readily available from the
manufacturers, but for lamp fuses... (I've never seen any published).

--
Andy

Steve Firth wrote:
On Thu, 14 Dec 2006 21:08:10 +0000, David Hansen wrote:

There is a saying, if you think you
understand something then try writing computer software to model it.
If the software works then you really do understand the subject.

That's ********. I've written several computer models, all of them modeling
with varying degrees of accuracy systems of assorted complexities. I can't
pretend to have understood the subject well for every model.

Not to mention that unless you actually do understand the model, and
have verified it against underlying facts, you can come up with a model
that seems to work, but doesn't except in the test cases.

Modelling something doesn't help, if your understanding is flawed, and
you are just modelling your understanding, if your understanding of the
system is self-consistent.

Andy Wade wrote:

At a particular fault current:

(i) if the operating I^2*t of the MCB is less than the pre-arcing
I^2*t of the fuse then the MCB will discriminate in favour of
the fuse (i.e. breaker trips, fuse does not blow);

(ii) if the operating I^2*t of the MCB exceeds the total clearing
I^2*t of the fuse (pre-arcing and arcing) then the fuse will
discriminate in favour of the MCB (fuse blows, breaker does
not trip);

(iii) if the operating I^2*t of the MCB exceeds the pre-arcing I^2*t
of the fuse, but does not exceed its total clearing I^2*t then
both devices will operate (no discrimination, fuse element melts
but the arc is extinguished by the MCB).


To add a bit more detail...

I^2*t (pron: "I-squared-T") is a measure of the electrical energy that
is let through the fuse or MCB during a current surge. Some of that
energy is absorbed by the device itself, either to heat the wire in a
fuse, or to give an electromechanical kick to the moving parts in an
MCB.

In a fuse, the pre-arcing I^2*t represents a "point of no return", where
enough heat has been absorbed to melt the wire, so it is definitely
destined to break. However, it takes a while longer for the molten metal
to flow, and for surface tension to pull the ends apart.

Thus you can easily have a situation like Andy's case (iii) where the
current surge takes the fuse beyond its point of no return while also
operating the MCB. Then, as Andy says, it is often the MCB that breaks
the circuit, before the fuse has time to pull apart... but the fuse is
still found to be melted.



--
Ian White

On Thu, 14 Dec 2006 23:13:50 +0000 someone who may be Steve Firth
wrote this:-

There is a saying, if you think you
understand something then try writing computer software to model it.
If the software works then you really do understand the subject.

That's ********.

Ah, proof by assertion and rudeness in three words. Excellent.

I've written several computer models, all of them modeling
with varying degrees of accuracy systems of assorted complexities. I can't
pretend to have understood the subject well for every model.

Noted.


--
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

On Thu, 14 Dec 2006 23:59:30 +0000 someone who may be Andy Wade
wrote this:-

I^2*t data for MCBs should be fairly readily available from the
manufacturers,

It is.

but for lamp fuses... (I've never seen any published).

Fuses built into lamps are not something I have discussed, not the
least because I have never seen data on them.


--
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

In article ,
Andrew Gabriel wrote:
[snip]
Once an open wire fuse melts, it can take a number of mains
cycles before the vapour has dispersed sufficiently for the
arc to be quenched. Meanwhile, an MCB can operate in less than
a half cycle, whilst the fuse arc is still running. If you look
at a lamp which has tripped an MCB, you will see its fuses are
blown, but they were unable to quench the arc before the MCB
tripped. It's a case of a current which grossly exceeds both
the fault current ratings of both protective devices, and they
both trip. I've never seen a lamp with fuses trip an MCB without
also blowing its lamp base fuses (both of them if is has two).

I was going to do a post earlier on in this thread
to say that we've never had a blown bulb trip the
MCB. That was, until last night, when it happened
with an almost new 100W bulb (about 10 days old).

I've just knocked it apart. As you say, destruction
is complete. The support wires are there, but the
filament has disappeared, as have both fusewires in
the stem of the bulb.

SWMBO did note that it didn't do the normal 'plink'
as it went, it did a nasty-sounding 'splat'. That
could have been the arcing.

--
Tony Williams.

"MM" wrote in message
...
Sometimes when a bulb blows (ceiling light) it causes the ELCB for the
circuit to trip. That is, if the bulb is in one of the upstairs rooms,
only the upstairs lighting ELCB is tripped. The power points are
unaffected, as are the power points and lighting circuits downstairs.

Is this just because modern wiring is so much more "safe" than once
was the case? This house was built in 2004.
Two solutions :-

1. Change MCB (I am sure you meant MCB not ELCB) to type C.
(www.tlc-direct.co.uk) as this has a higher over-load/time trip. This worked
for me in my hall lights (4 x 60W). Got fed up of coming home, turn on hall
lights and flash and still in dark. In fact very dark as the IR triggered
outside light is on same circuit, so is the garage lights which makes
getting to the breaker very hard.

2. Change to low enrgy bulbs.

On Fri, 15 Dec 2006 08:44:09 +0000, David Hansen wrote:

On Thu, 14 Dec 2006 23:13:50 +0000 someone who may be Steve Firth
wrote this:-

There is a saying, if you think you
understand something then try writing computer software to model it.
If the software works then you really do understand the subject.

That's ********.

Ah, proof by assertion and rudeness in three words. Excellent.

Life must be so difficult for you, blubbering every time someone says boo!

Ian_m wrote:

Two solutions :-

1. Change MCB (I am sure you meant MCB not ELCB) to type C.
(www.tlc-direct.co.uk) as this has a higher over-load/time trip. This worked
for me in my hall lights (4 x 60W). Got fed up of coming home, turn on hall
lights and flash and still in dark. In fact very dark as the IR triggered
outside light is on same circuit, so is the garage lights which makes
getting to the breaker very hard.


1.5) install a non maintained emergency light at the CU and anyplace
enroute to it that may prove difficult to navigate when dark.

(and to be fair 1) is not a total solution - you can still trip those on
bulb failure - just not as often.

2. Change to low enrgy bulbs.




--
Cheers,

John.

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On Fri, 15 Dec 2006 16:45:04 +0000 someone who may be Steve Firth
wrote this:-

Life must be so difficult for you, blubbering every time someone says boo!

Ah, someone else trying to give the impression that they can read my
mind. Don't give up the day job and take up mind reading, you are
not any good at it.


--
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