All lights out, all sockets still working

[FrodoOne]

Electricians gain much pleasure from calling lightbulbs "lamps" and lamps "luminaires."

Or in some cases "lanterns"

They also like saying that "bulbs" are planted in the garden.

It's just a harmless foible.

That which we call a rose by any other name would smell as sweet.

Also, Americans even refer to Fluorescent Tubes as "bulbs".

 

[FrodoOne]

I think you will find that what happens is that an arc strikes up inside the lamp, rather than a short bit of the filament falling across the support wires. Some such lamps used to include a fuse, to prevent the main supply tripping.

While I consider that you are correct and I have seen this stated elsewhere, do you have a reference which discusses this phenomena?

 

[SFK]

Frodo,
With regards to a reference which discusses this phenomena there is a nice 'discussion' (but no definitive outcome) here:

turn on light, bulb blows, circuit breaker trips - what caused what?

The other day I flipped a light switch on. Immediately both the bulb burned out and the circuit breaker tripped. Is it possible that the failure of the light bulb (filament burning out) caused the circuit breaker to trip? Or is there a more probable explanation?

www.google.com

 

[Mottie]

Our light circuit breakers were always popping every time a bulb blew when switching it on. GU 10’s in the kitchen (the worse culprits) and SBC candle bulbs in the chandeliers. Changed the kitchen bulbs for LED's a couple of years ago and not had one blow since (would have had to change all 8 bulbs at least in that time) and recently replaced one of the chandeliers with a different lamp that has LED's.

 

[Harry Bloomfield]

Frodo,
Nice 'discussion' but no definitive outcome here:

turn on light, bulb blows, circuit breaker trips - what caused what?

The other day I flipped a light switch on. Immediately both the bulb burned out and the circuit breaker tripped. Is it possible that the failure of the light bulb (filament burning out) caused the circuit breaker to trip? Or is there a more probable explanation?

www.google.com

On a lamp which runs cap uppermost, the current carrying support wires also come down from above, which means that if the filament burns out, it will fall away from the wires rather than being able to short them. Additionally, if you happen to be in sight of a lamp when it blows and trips the MCB you will see a bluish coloured glow, from the arc.

 

[FrodoOne]

On a lamp which runs cap uppermost, the current carrying support wires also come down from above, which means that if the filament burns out, it will fall away from the wires rather than being able to short them. Additionally, if you happen to be in sight of a lamp when it blows and trips the MCB you will see a bluish coloured glow, from the arc.

Yes.
I do realise that my previous "answer" was "simplistic" and that arcing can take place, as is often evident from the deposit on the inside of a "failed" incandescent "bulb".

However, I still ask, are there any references which discusses this phenomena?

 

[Harry Bloomfield]

Yes.
I do realise that my previous "answer" was "simplistic" and that arcing can take place, as is often evident from the deposit on the inside of a "failed" incandescent "bulb".

There was nothing simplistic about it, you made a clear statement, which was incorrect, so I corrected you. I don't see a need to provide any references, because the mechanism of tripping is so obvious. How else can a high current flow through a filament which has just burnt out, other than via the process of an arc forming?

 

[FrodoOne]

There was nothing simplistic about it, you made a clear statement, which was incorrect, so I corrected you. I don't see a need to provide any references, because the mechanism of tripping is so obvious. How else can a high current flow through a filament which has just burnt out, other than via the process of an arc forming?

I am sorry if it appears that I have offended you.
Such was not my intention.
I would REALLY like to have an authoritative reference to how such an "arc" can be produced in the situation concerned, although it would not necessarily "flow through a filament", and I have not been able to find one.

Please advise.

 

[Harry Bloomfield]

I am sorry if it appears that I have offended you.
Such was not my intention.
I would REALLY like to have an authoritative reference to how such an "arc" can be produced in the situation concerned, although it would not necessarily "flow through a filament", and I have not been able to find one.

Please advise.

I am not offended, it is just something which is so very obvious it needs no reference to explain it.

The brief arc is formed by the melting tungsten of the filament. The arc has a much lower resistance than the filament, produces more light output, and consumes more current - which results in the MCB tripping.

 

[JohnD]

I am sorry if it appears that I have offended you.
Such was not my intention.
I would REALLY like to have an authoritative reference to how such an "arc" can be produced in the situation concerned, although it would not necessarily "flow through a filament", and I have not been able to find one.

Please advise.

Plasma.