A Novel Theory

[Eric Tricia123]

Hi

Just a quick one I heard a weird theory the other day and just wanted to see other people's opinions

A fire man told a friend of mine you know if you have good electrics in your house if when a light bulb blow the trip goes

I assume he means fuse, rcd, rcbo or MCB

Just wondered if any one had been told this before???

 

[Barx]

Not been told it but most cheaper old filament stlye bulbs will take out a modern mcb when they blow. Never seen a low energy blow to know if it is same. But I would assume it wouldn't be.

 

[kerching]

I would love to know the thinking behind this and then I can form a considered opinion. However until such times I would think it was bucking frollox

Back in the day I was called to a customers once to meet with 'Trumpton' [Fire Brigade for those who do not understand my humour]

There had been a fire and Trumpton had put this down to an electrical fault. My job was to prove otherwise.

I asked for the seat of the fire and was directed to some burnt wires. On being informed that the said wires had burned I pointed out that there had been a fire and this had burnt the wires.

When pressed further as to why [his words] 'You think you know more/better than us...'I girded my loins and in no uncertain terms let rip with both barrels

A) those wires are TV Co-Ax

B) there is NO electric in this or the adjacent buildings

....their priceless response was 'Well it looked like an electrical fire but it must have been something else, is there any gas...'

............................... :coat

 

[Andy™]

HiJust a quick one I heard a weird theory the other day and just wanted to see other people's opinions

A fire man told a friend of mine you know if you have good electrics in your house if when a light bulb blow the trip goes

I assume he means fuse, rcd, rcbo or MCB

Just wondered if any one had been told this before???

an MCB tripping when a lamps fails does not mean you have good electrics. it only means that the current flowing when it failed was enough to trip the MCB, and that the MCB has done its job

 

[steptoe]

where is our fireman sparky when we need him? :|

 

[Evans Electric]

I've noticed over the years that a lot of Firemen seem to double up as Electricians, But not the other way round.

I just found the Trumpton Method of testing , its on page 390 of the BRB , must have missed it!!!

To check disconnection times without instruments , insert cheapo GLS lamp (bulb) from nearest supermarket and switch on.

Wait at Consumer unit with stop watch and send your mate to whack said lightbulb with cricket bat.

If breaker has operated before you hit the stopwatch, all is well .

 

[remustered]

Trouble with being a fireman is that...a good fireman is a jack of all trades, master of none....this due to the wide variety of trouble they have to deal with. Problem with that is people expect them to know everything and some simple firemen believe it.....moral is there are numpties in all trades.:banghead:

 

[ProDave]

All he is saying really is if an MCB trips, then it means you HAVE MCB's so you have a "modern" consumer unit, as opposed to an old fuse box with rewireable fuses, which very rarely blow when a bulb goes.

 

[Andy™]

All he is saying really is if an MCB trips, then it means you HAVE MCB's so you have a "modern" consumer unit, as opposed to an old fuse box with rewireable fuses, which very rarely blow when a bulb goes.

but what if the installer has fitted C type? no trip on lamp failing. must be dangerous wiring then

 

[Brian 157]

6A Type Bs and the old BS3871 type 1s often trip when GLS lamps blow (particularly Crabtree Starbreakers & SBs in my experience).

I did carry out some remedial work in a Trumpton Station where the main isolator (TP&N MEM Excel)caught fire, apparently there had been a loss of one phase & when the enclosure was opened the whole thing went up in flames... I was told they all ran around like headless chickens...

 

[Technician]

I had this in my house; a lamp would fail and cause the

C/B to operate. Not an indication of good electrics as

Andy says and this would not cause the operation of a

BS3036 because this takes longer to operate in the event

of a high fault current, longer than a circuit breaker. (Pro Dave)

For some reason, there is a surge of current just prior to

failure of the element.

 

[kme]

For some reason, there is a surge of current just prior to

failure of the element.

As I understand it, the lamp, when it begins to "blow", generates a ball of plasma within the envelope, which, for a few milliseconds, draws as much current in as it possibly can, to sustain itself. However, the filament leads are unable to deal with this, plus the evacuated nature of the envelope, combine to limit the magnitude that the plasma can grow before extinguishing....

or summat like that, anyway :slap

 

[lineman]

Always thought that it was a L-N short when the filament gives way due to decreased resistance. But thanks for the real explanation. Often wondered why!

 

[Technician]

Reading that KME I would hazard a guess that the plasma

(yes, I am taking you seriously) has a greater conductance

than the failing element which, in parallel with it, causes the

total impedance of the lamp to fall thus leading to a massive

surge in current on failure.

I am reminded of my investigations into electric distribution

circuits in potentially hazardous atmospheres and finding out

that ring final circuits were never used. Precisely because

of the instability which can lead to overheating in one leg with

the protective device remaining intact.

 

[kme]

I did mean it seriously mate

 

[Technician]

I read you a-right then?

 

[kme]

You would do bud - you come from the 5th member country of the UK !!!!!

The amount of people who try to tell you that Yorkshire is "part of England".........If I had 10p for every time I`d heard that...........

https://www.youtube.com/embed/Xe1a1wHxTyo?feature=oembed :slap

 

[Technician]

You would do bud - you come from the 5th member country of the UK !!!!! The amount of people who try to tell you that Yorkshire is "part of England".........If I had 10p for every time I`d heard that...........

https://www.youtube.com/embed/Xe1a1wHxTyo?feature=oembed

KME I have had that trotted out to me time without number.

Best part of it is... I only arrived there because my Dad's

work took him there.

Some around the country describe one of its major cities as a

cemetery without the lights.

I cannot imagine any other city wanting to name one of its

residential roads after the city of the dead.