It is usual to have them connected to the one cooker unit.
The problem with this approach is that the circuit fuse is designed to protect the wiring as far as the appliance fuse. If you have a gas hob or oven or possibly even an electric oven, they are likely to only have 13A flex fitted. If you wire this directly into a cooker outlet, then the circuit fuse, being likely 32A or higher, will allow the wiring to overheat and possibly melt before it itself blows or trips. If you have an electric hob, then it will nearly always be wired directly, but it will also have a suitably rated cable to cope with the load and this will generally match the circuit rating capacity. If you have a gas hob, then whatever oven you have is probably only 13A at most (even if it is electric), and you might get away with hooking both together to the same fixed outlet *provided* you do the right thing at your consumer unit and fit a 15/16A fuse or breaker.
Appliances rated at 13A or less should usually be connected via a suitably rated fused 13A plug to a socket. If your cooker outlet also has a socket (a rather old style, but still around), then you can use that provided the total load on the outlet and socket combined won't overload the fixed cable or the fuse protecting it.
If your cooker outlet is the type with a socket use that for the oven via a
13A plug. Wire the hob direct using 6mm cable. If it's the newer type with a switch above the unit and an outlet below you could use the outlet to supply an additional socket for the oven to plug into (total loading is unlikely to be as high as the old combined cooker - 6.5 + 2.5 =9kw , combined ones were in the order of 11kw) Regards, RichardHomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.