I've a wall-mounted electric oven. Or rather I did have before a small, smouldering fire started and neary burnt my house down. The fire brigade informed me there was no air gap (it was fitted 5 years before I owned the house and sat flush onto chipboard) which caused the issue. I've found little in any oven installation instructions that details the need for a gap.
So I wondered - is it required? Do all ovens ship with 'feet' that enable the oven to sit within a cabinet with the required clearance?