Safe to have oven powered via hob?

the oven and hob are separate appliances so they should be wired in such a way that they can be isolated separately, not jerry rigged one into the other. and then wired to a switch. That's a bodge. If either appliance develops an electrical fault you will lose the option to use either. Typically double ovens need their own circuit whereas single ovens utilise a 13 amp supply. Induction units definitely need their own supply unless you get one that has power management, some of these can be wired to a 13 amp supply. The instructions for both appliances will explain how they should be installed

Give that an induction hob could be pulling more current than the old hob - take it that it was electric, not gas with an electric connection for the ignition - an electrician should be engaged to calculate the load of the Hob & Oven running at the same time and if the cable & breaker are the right size & rating. A standard cooker switch will be rated as 45a, the supply cable & breaker is what is needed to be calculated, by the load of the proposed appliances. Hope this helps.

Can’t be connected in series, but it can be connect on dual connection unit. If the cable feed is 10mm, if it is 6mm then would be separate. Would get a professional to look and make a right decision.

I see nothing wrong in wiring the hob and oven together, if it's a single oven however, I would install a single socket (as some ovens now come with a fitted 13A plug) or a spur to fuse down to the size of the cable for the oven, normally 1.25 - 1.5 sq mm. The hob (unless a high frequency switching type - which again runs on a 13A plug) can then be wired into the cooker outlet. However as the appliances are hard wired and in a restricted area (Kitchens, bathrooms and outside buildings) will require an electrician to install, test and certificate. With an electrician fitting, all of the loading can then be checked and diversity applied etc. I can't see where the other comment mentions jerry rigging and bodging come into it, I agree it's nice to have everything on separate isolators but not always possible if you have a nice tiled kitchen, if you consider a standard free standing cooker, if part of it failed you would be in the same situation as mentioned. Would advise an electrician installs and tests as the kitchen having many metal class 1 appliances there is a real danger if wiring is not tested for correct earthing etc. Part P 2005/6 only allows a competent person to carry out this kind of work (this was brought in after the death of a government minister daughter caused by a dodgy kitchen fitter who was not electrically qualified.