Boiler Conundrum

[securespark]

Ah, didn't ask.
I'll find out.

I'm here at the moment and I've just taken a picture.

 

[JohnW2]

I'm here at the moment and I've just taken a picture.

Thanks.

I suppose one of the most pertinent things that reveals is that it was not an MCB but, rather, an RCBO that tripped - so the trip was not necessarily due to over-current(although it probably was!)

 

[securespark]

Yes, she described it as an MCB, but thinking about it, that was unlikely.

I think it was more than probably over-current or short circuit as the 3A fuse went simultaneously.

 

[JohnW2]

I think it was more than probably over-current or short circuit as the 3A fuse went simultaneously.

Yes, that's what I wrote.

However, on reflection, an L-E short 'of negligible impedance' (aka 'short circuit') would result in enough current to blow the fuse, and the RCBO would probably also operate - but I suppose that, at least theoretically, one could not be certain whether over-current or residual-current 'got in first' to result in the RCBO tripping