BIG BIG Range Cooker.

Zoomup:

I wired up a b


I warned the owner that it is not a good idea to turn on all ovens and hobs at once.


Z.

Why did you do that Zoomy?

Grumpy:

Zoomup:

I wired up a b


I warned the owner that it is not a good idea to turn on all ovens and hobs at once.


Z.

Why did you do that Zoomy?

To cover myself and to be helpful. 58 Amps of possible load if all heating elements are turned on, and the two ovens are warming up, say initially before thermostats cut anything out, could trip the 32 Amp M.C.B. after a few minutes. Also the M.C.B. when in use is likely to run warm and become more sensitive to load currents. Or if the thing has all controls turned on and the supply is interrupted and then the whole beast demands full plated current when the supply is reinstated it may trouble the M.C.B.


Diversity is a gamble. There could be a time when all heating elements are in use and demanding current.


I note that B.S. 7671 does not have a definition for "diversity" any more.


Also, the new house is a small modern wooden framed bungalow type and may not have a full 100A main fuse.


Z.


 

AJJewsbury:

14kW of cooking appliance, after the usual diversity rules comes out at 25.26A - so 32A should be fine - you could even add a socket!

    - Andy.

I am sure that when the "diversity" rules were considered initially for cooking appliances, the cookers were rated at about 6kW max. This beast is over twice the rating of most stand alone four ring, grill and oven cookers of the 1950s.


Edit. Add: The I.E.T's Electrical Installation Design Guide says about "diversity": Referring to Table 3.2, "The allowances for diversity in Table 3.2 (Table A2 of The Onsite Guide)  are for very specific situation and can only provide guidance. The figures given in the table may have to be increased or decreased, depending upon particular circumstances."


This table includes the ancient cooker diversity calculation of:


10 Amps. plus 30 per cent of full load cooking appliances in excess of 10 Amps plus 5 Amps. for a socket outlet. O.K. perhaps for a 1960s small 6kW cooker.


 

 you could even add a socket!

    - Andy.

Yes, lets add a 2.2kW electric kettle or 2.5kW washing machine as well.


Z.

Grumpy:

Well, if it helps you sleep any easier Zoom, I've just got a Belling 110cm all electric range cooker. The MI's state a 32A supply and so far it's been fine. Perhaps I should update you though on December 26th!

A very good point.


Z.

mapj1:

The cooker may be bigger than the one it replaces, but the real question is if it will be required to cook more food. If a larger ring is used to boll the same volume of water or heat a frying pan of given size, it will do it quicker, but unless a higher temperature is selected, it will then spend a greater fraction of the the time with the thermostat in the off state, so the heating, of food, of cables and of company fuse, all scale more or less in proportion.


So someone buying a bigger cooker for a new extended family or larger dinner parties is more of a risk for the cables than someone talked into an upgrade by the kitchen salesman whose domestic loading has not changed.

Mike,

This is a new cooker Mike, no previous cooker was installed, and no cooker control switch exists.


Z.