A fuse blowing oddity.

[Burnerman]

I wonder if anyone could explain this to me, please?
Lady next door turns one of her cooker hobs on and all the electric goes off. She calls me.
I find that the hard wired cooker has its own dedicated 30A fuse, as expected. Its on an elderly 6 way Wylex consumer unit with the wired fuses. This fuse was intact, as were all the others.
The separate RCCB breaker had not tripped.
The main electricity boards incoming fuse had blown - a 60A cartridge type. I replaced this and normal service was resumed - apart from the kaput hob, of course.
Why didn't the 30A fuse in the consumer unit blow before the larger Boards fuse? I don't understand!
Thanks for reading, and have a good evening.
John

 

[Spark123]

Pull the 30A fuse out first and have a look in it, make sure it is acutally 30A fuse wire.
The 60A could have had the odds stacked against it with additional loading from other circuits and a rewirable having a higher fusing factor than a cartridge.
Also you shouldn't really be tampering with DNO property

 

[Burnerman]

Yep, I'll check the 30A fuse tomorrow - although at a glance the wire seemed about right.
I realise the implications about the main fuse - the seal was broken already (truthfully)!
The only other appliance on at that time was a radio, I think.
Cheers for the reply.
John

 

[londonboy]

Ive seen the main fuses blow a few times, I understand its due to age and the fuse becoming more fragile.

 

[ColJack]

that 60A fuse might have been overloaded for a long duration and was already fairly hot before the hob went..

 

[Burnerman]

Fair comments guys and I'm certainly not one to argue.....the fuse was in fact replaced 12 months ago due to another hot plate failing in exactly the same way. That time the fuse was replaced by a 'proper' sparky who didn't replace the paper seal.
So, I'll check the original wired fuse for 30A wire...failing that I'll just forget about it for now.
I appreciate all of your comments!
John

 

[AndyPRK]

Replace 30A fuse wire or fit a plugin MCB.