Oven/grill cable fault

[Marmalade]

Evening all.
I need some guidance on a cable fault on an oven grill combo.
Customer phoned to say that the oven/grill was causing the 32A mcb to trip in the CU (Crabtree Starbreaker)
I called in to the house to investigate and yes it was the mcb that was tripping so I thought it may well be a short circuit in the appliance which was 11 years old according to the customer.
Disconnected the appliance and tested no short circuit found, reconnected, re-energised the mcb and the it tripped within 10 minutes but not instantly with only the clock on, oven/grill turned off.
Disconnected the appliance to carry out an IR test with MFT on the cooker cable, CU to cooker switch L&N,L&CPC,N&CPC all>999, cooker switch to appliance cable same results.
Reconnect appliance ,tripped, replaced mcb with one I had on the van same result re-fitted original one.
Connected new cable between cooker switch and appliance does not trip?
I am confused to say the least.
PS. the cooker mcb was not on the RCD side of the CU, it is now.
Nigel

 

[Andy™]

wouldnt be hard to strip outer sheath to check inner cores for damage that's only shorting when its in a certai position

 

[binky]

Personally, I would have left it off the RCD, you don't really need it unless theres a socket on the cooker isolator.

What type of cable was it connected with? The back of ovens is a harsh environment, with lots of heat, and steam from the oven. Most people seem to like using fte, which isn't really designed for that environment .