If you did that and the result was a massive bang and no power to your house, what would you do then?
Or nothing appeared to happen but when you pulled on the oven door handle you got a fatal electric shock?
The chances of that are nil unless I was really stupid (even then I am hard pushed to think how I could create that scenario). All I am doing is extending a cable. This involves connecting live, neutral and earth to live, neutral and earth, checking I have done it correctly, checking again, and checking nothing has pierced or pinched the cable. I am capable of doing that.