I have seen both, but I do not like T&E in situations where it is called upon to behave as a flex  - so a built-in oven in a cupboard frame  that never moves is far less of a concern than a free-standing cooker that gets pulled out to mop the floor beneath every  few weeks. I have would no issue with the right size of HO style flex in either situation. 

I have been known to use crimp bootlace ferrules or even pin-crimps  on fine stranded wire in terminals in things like isolators that do not grip it properly otherwise.

Also in the mix of things to consider  some cooking appliences have terminals that on inspection are really only suited to flex and are sometimes unhappily forced to take wire that is too stiff and are then mechanically stressed.

Somtimes a bit of local 'professional opinion' over-rules maker's instructions that were cleary written for a different situation (or sometimes written for a totally fictional situation it feels like.. )
Mike


PS

Bootlaces Pin crimps for fine stranded wire

I agree with you there Mike.  Some ovens need a Flex with a crimp or Ring crimp on the end. 

According to regulation 521.9.3, rigid cables are permissible in the absence of vibration.

Larger sizes of T&E are stranded rather than solid, and experience suggests they survive well enough occasional movement, so I've no real objection provided they can be positioned to avoid too much heat. Some of the modern connection facilities on appliances do seem to be designed for round flexes though and getting wider/stiffer T&E into them can be a pain  - so often I do use H0 flex - usually with uninsulated 'bootlace' ferrules to stiffen up the ends to go into tunnel terminals.

   - Andy.

It would then depend on how many time the customer pull the oven out?  This would be for a free standing oven so they can clean underneath if in a cupboard then it may never come out unless there is a fault or a diligent IECR or Pat.

T&E is not that great for UV.  Not sure how much UV would get behind a oven but I have seen outdoor flood lights with T&E and the weather and UV destroy the cable. 

It’s not good for SY cable either. 

AMK said:

According to regulation 521.9.3, rigid cables are permissible in the absence of vibration.

Fan ovens have inherent vibration.

Sergio Fernandez said:

It would then depend on how many time the customer pull the oven out?

Perhaps ... might also depend on:

• Sources of vibration close to, or within, the oven itself
• Manufacturer's guidelines/instructions (if any)
• Type of terminals or connectors (for example, some have a rewirable connector suitable for flex, or are provided with a connector with flex).
• Type of cable restraint and how that works.
• How the manufacturer envisages the oven will be repaired and/or serviced.

Is that cabling for air conditioning in that picture?  I have seen Air Con installers using all sorts of inappropriate cables. 

I would consider that HO7 flex is preferable on the grounds of flexibility and heat resistance, but that twin with earth is just about acceptable

Would I install a cooker in twin with earth ? Probably not.

Would I give an adverse code to an existing twin with earth to a cooker, no I would not unless stress or damage was observed