Smeg SUK91MFX5 range cooker - help!!!

Hello, I hope someone can help.

Have finally had our Smeg range cooker installed after updating electrics/gas in our old house to accommodate it.

On turning on:

Gas hob working fine inc electronic ignitions.
Electric clock lit.
Oven lights come on when door is opened.

then....

Go to turn on oven (single oven has 2 fans) and it trips the electric in the whole house. Any ideas?

Main board has a separate 40amp for cooker, 10mm cable going to cooker switch and from there 2.5mm going to oven. The original Smeg cable (H05RR/F)was not long enough to reach cooker switch so was replaced with 2.5mm heat resistant cable, apparantly the original has copper and the replacement has silver (whatever that means!) would this affect it??

Plus, why does the whole board trip?

Thank you in advance. AJ

when you say the main board trips what exactly does trip?

Have you really got a 2.5 mm cable connected to a 10mm cable protected by a 40A fuse?

I am going to assume the above are true (please confirm)

I will guess it is your rcd tripping, this will be becasue of an earth fault.

what rating (In watts) is the cooker

reason i ask is becuse it is dangerous to have a 2.5 mm cable connected to a 10mm cable protected by a 40a fuse.

If you get an overload, the 2.5mm cable will go before the fuse does.

You've got two problems here by the sounds of it.
One, Breezer has already covered and I'd like to add that what's been done is a fire hazard. The 2.5mm cable will get extremely hot if a fault develops.
Two, sounds like either a duff element or fan motor or a wire has come loose and is earthing.

What you need to do now. Switch it off at the main switch, pull the 40 amp fuse and get someone for repairing the cooker and more importantly someone to sort out the electrics.