Faulty Circuit While Replacing Light Bulb

[Softus]

The failure of the lamp caused the dimmer to toast...

Are you saying that the current temporarily passing through the failing lamp exceeded the rated capacity of the switch?

If so, would the result not have been the same if the switch had been off at the time the lamp was inserted, and the circuit energised afterwards?

The short took out two 32A type B breakers (no discrimination) while leaving a 13A BS1361 intact.

OOI, do BS1361 fuses have stated 'type', compared to MCBs?

 

[securespark]

The failure of the lamp caused the dimmer to toast...

Are you saying that the current temporarily passing through the failing lamp exceeded the rated capacity of the switch?

Experience tells me that failing lamps will often toast a dimmer. That is why some dimmers had/have fuses in them, to protect the switches.

Modern MK dimmers no longer have these and carry a warning that all lamps connected to their dimmers must be internally fused or else dimmer failure will result.

 

[JohnD]

I think I can hear someone shouting "Osram!" in the distance.

 

[Softus]

Was it Eric Morecambe?

 

[Spark123]

The failure of the lamp caused the dimmer to toast...

Are you saying that the current temporarily passing through the failing lamp exceeded the rated capacity of the switch?

The currents involved in a lamp failing are quite high, quite often high enough to operate an MCB. Triacs which are one of the main components of a dimmer switch cannot withstand this current and can fail short or open circuit. Lamps with integrated balotini fuses help reduce the resulting fault current level.

If so, would the result not have been the same if the switch had been off at the time the lamp was inserted, and the circuit energised afterwards?

If the short was present then probably.

The short took out two 32A type B breakers (no discrimination) while leaving a 13A BS1361 intact.

OOI, do BS1361 fuses have stated 'type', compared to MCBs?

BS1361 fuses do not come in types as such (can have different type KA values but thats another chapter), neither do BS1362. BS88 fuses can come in different types though.

 

[RF Lighting]

A bit off topic I know, but never mind

I have seen BS88 fuses with types Gg (general purpose) and Gm (motors)
Are there any other types?

Also all the newer cutouts round our way have BS1361 type IIb fuses. What does this type number refer to, and are there any other types?

 

[Spark123]

Theres another type of BS88 motor fuse aM although I have not come across them.
Re BS1361, http://www.biagmbh.com/katalog/pdfs/96/9692.pdf