most hobs have a clearance measurement in the instructions, normally around 30mm to 50mm from combustable materials. any draws underneath will need to have some protection fitted above them. As gas man has said, a piece of fire board/asbestlux.
i went to a hob for a friend of a friend a few weeks ago and told them that i would only fit it if clearences and fire board was fitted and pipework altered to suit. Somebody else fitted it for them, i got asked around to take a look.... gas tap fitted infront of plug socket, no clearances meet and because they misplaced the clips it was not even secured down to worktop. I just laughted refused to touch it and walked away.