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 ...

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.

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

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.

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.

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..

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 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

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.

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 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

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 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

"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.

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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