Replacing ceramic hob for induction - basic questions

[rupertcacatua]

Hi all, planning to replace my electric ceramic hob for an induction one.

Current ceramic hob is:
Baumatic B12SS - 230v/400v 3N 50/60Hz 6kW 26.1A, min fuse protection rating 30A.

The current setup is as follows:
CCU>1xB32 MCB>connected to 2x red cooker switches:

• Switch 1: connected to hob above
• Switch 2: connected to 2x electric Neff ovens, EACH rated 230/240v 50Hz 3.6kW 16A (models B6774N0GB and B1524N0GB)

Question 1) If the B32 MCB is 32A rated, doesn't that mean that it can support up to a max of 230x32=7.4kW, and if so, 6kW (hob) + 3.6kW (oven 1) + 3.6kW (oven 2), far exceeds the maximum tolerance of this single MCB, when all 3 appliances are at full power? Granted, only on very rare ocassions I have used both ovens plus 4 hobs (Christmas...), and nothing actually tripped. Have I miscalculated the tolerance; is this a safe setup for these appliances?

Question 2) Considering swapping the above hob for 32A wired 7.4kW rated Siemens Induction EX675BEB1E. Is the above setup suitable for a direct swap?

Many thanks

Rupert

 

[telectrix]

you need to take diversity into account.this means that the elements willnot all be drawing juice at the same time, except when initial switch on ( thermostats switching on and off). a 32Acircuit with6.0mm cable has been good for coooking appliances upito 15kW for donkeys, so just connect your new hob. if in doubt, get a local spark to test the circuit.

 

[Midwest]

As above. With diversity, I have your old set up as drawing 38A, and the new one as 40A. As the old set runs ok, can't see the new one not either. If it was a new install, you would probably have two 32A supplies or one 40A.

 

[rupertcacatua]

Many thanks guys. For added info, the CCU is 5 meters apart from both red switches (in case this helps).
CURRENT setup on single 32A MCB: 6+3.6+3.6 = 13.2kW
NEW setup on single 32A MCB: 7.4+3.6+3.6 = 14.6kW

Please forgive my ignorance, checking on NEW setup:
14.6/230 = 63.5A (no diversity applied)
10A + 0.3 x 53.5 = 26.03A (with diversity)

Are my calcs above OK? Is this safe basically because 26.03<32? But what happens when I run all 4 hob zones plus an oven (which is something I do on an almost daily basis)? Will the connection not take it?

Thanks again for your time.

R

 

[Midwest]

Nope, I prefer applying diversity to each appliance separately, that’s how you will use them.

 

[Wilko]

Hi - as you’ve calculated, it is possible to overload the circuit with those appliances. The next question - how likely is it? If you were running a restaurant or some such then I’d say it’s not ok and a new circuit is required. If you envisage firing up all 3 appliances together, then for peace of mind I’d run a second circuit if that’s possible.

 

[marconi]

Interactive User Manual - https://media3.bsh-group.com/Documents/siemens.html?matNumber=9001330662&lang=en

The Induction Hob you are buying has a 'power manager' function which enables the installer or user to set an upper limit on the total power consumed - automatically. So with PM off, the factory setting is for a total inductive heating output of 7.4kW and no more. By selecting PM - look at the link - you can see that the total power can be lowered to suit lower capacity supply (down to a 13A plug). Of course this would mean that when all hobs are in use at the same time on high/full power settings it may take a little longer to first heat up the pans and its contents because a smaller amount of electrical power is spread over the same number of hobs.

Take a look at the reference for further information and setting 'C7'.

So, I would connect up to your current supply and if there are problems you can tweek the maximum power limit. This is what I did for my brother-in-law's new kitchen install and he likes cooking for the 5000 and no-one waits overly long.

 

[rupertcacatua]

Thanks all, and thanks @marconi for the very comprehensive and helpful answer.

 

[marconi]

Have you actually used yet an IH? They are a MArmite appliance if you get my comparison.

 

[Zerax]

I love my IH... no gas for me, so it's the best option by some distance !