I find the oven and hob situation flawed, with a stand alone cooker the normal supply is 32 amp, and this is normally taken to a cooker isolators
which is the same switch as used for some shower isolators, fact it says 45 amp on switch does not mean it has a 45 amp supply.
When separate hob and oven is used then a dual cooker connection unit is used
and with a single appliance a single version can be used.
For an oven under 13 amp a fused connection unit (FCU)
can be used to reduce the maximum current before automatic disconnection (fuse blows) but there are no FCU for over 13 amp in the UK.
There is nothing to stop one having a 45 amp supply to some cookers, however the question arises is it safe to have a 45 amp supply to an oven?
I have looked as oven spec sheets and many do not give an upper limit, however we must realise that a 200 amp supply would be silly, however it seems common to supply an oven with a 32 amp supply where it needs more than 13 amp and is used from same supply as the hob, the whole idea of the duel appliance connection unit would be pointless unless the oven was OK with a 32 amp supply which is the traditional size used.
However traditionally we use 6 mm² cable not 10 mm² and at one point we saw the 32 amp supply change to 40 or 45 amp supply, one would assume for a range cooker? My own stand alone cooker is 10466 - 12455 Watt so can use 50 amp, but recommended minimum supply is 32 amp, and my MCB in old house was 32 amp and RCBO in new house is 32 amp and they have never tripped with cooker supply.
The big question is unless a FCU is fitted to oven, can the oven be connected to a 45 amp supply, having seen the size of wires inside the oven I question this. It has been pointed out the oven only give a minimum supply requirement, but if over 13 amp then often 16 amp as minimum, since 32 amp is traditionally used I see no problem even when double the rated requirement, but would question if a 40 or 45 amp supply is appropriate.
I for a very short time worked for an appliance supply company with a gas safe man fitting cookers, the gas safe well corgi as it was then had all the equipment and if a unit was even ½ inch too close the gas appliance was not fitted. The electric side I had no test equipment provided, it is normal for any tools which wear out or require calibration to be provided, so I did not have my own insulation resistance tester, loop impedance tester, and RCD tester calibrated, and I had no intention of getting it done, which is why I left, did not want to sign off work without testing.
But it seems electricians had been fitting cookers of years without testing. Hopefully that practice has now stopped, but the Part P regulations are a bit vague as to if a compliance or completion certificate is required even in Wales to fit a cooker, I would assume they are not required, even the minor works certificate only covers up to the cooker connection unit or FCU so often no paper trail to show done correctly.
Since an oven is an appliance it would be covered by inspection and testing of in service electrical equipment, and the new English landlord law links
The Electricity Safety Quality and Continuity Regulations 2002 said:
“consumer’s installation” means the electric lines situated upon the consumer’s side of the supply terminals together with any equipment permanently connected or intended to be permanently connected thereto on that side;
so cooker would be tested with an EICR, but only for rented accommodation in England, in most cases once fitted the installation is never checked.
I personally would use only up to 32 amp overload device, unless the oven is supplied from a FCU, but can't really say using a 40 or 45 amp overload is wrong, but would not do it myself.
When doing a PAT test we rarely have the manufacturers instructions so unlikely we would know which oven can be supplied with 45 amp and which can't.
