Wiring a 6kw / 30A ceramic hob to existing 40A 6mm wall plate

[kreatiff63]

I've installed a ceramic hob and would like to check if I've done it correctly as I have a replacement coming tomorrow and would like to get it right.

The configuration is as follows:
40A circuit breaker feeds original wall plate and is now burried in the wall and has the new 6mm cable connecting to it. From this I've simply wired the new 6mm cable into the old wall plate (in the wall), and run this under the floor to the other side of the room to another wall plate. From this I have the heat proof 2.5 cable feeding the hob. The hob worked when checking it, but then failed to turn on after boiling some water last night. I have a replacement coming tomorrow and want to get it right if I've made any errors

Ceramic Hob:
Baumatic (Hoover/Candy)
30A
6.1kw

 

[SJD]

You say the original wall outlet plate is buried in the wall - which I take to mean plastered over? Assuming it has screw connections, this will not be maintenance-free, one of the connections could have worked loose - which with a high current appliance could easily overheat and fail. Either the joint needs to be maintenance-free connectors, or accessible for inspection.

Quite apart from the above issue, hopefully there is not a buried cable in the wall with nothing to indicate its presence. The outlet connection plate would do that, but once buried it doesn't. Not so much likely to cause the issue you are having, but possibly not compliant with building reguations.

Re the 2.5mm2 heat proof cable, I suspect it is only rated to around 25A, and 4mm2 would be more typical for use with a 30A appliance. Though the 6.1kW you also mention is only just over 25A, and likely the cable will be just about OK.

As always, a posting photograph might generate more comments.