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Electric cooker switches

Arran Cameron
I hope that this doesn't come across as a daft question...


Why do most electric cooker switches have an in-built socket? Do analogous cooker switches exist in other countries that use different types of mains sockets?


I used to think that the socket was for plugging in a gas cooker electric ignition, but there is no real reason for having a separate circuit from the ring main for this.
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    In the middle of cooking Christmas dinner with every heating element on full blast, an in-law demands a cup of tea. The kettle is plugged into the socket on the cooker switch, overloading the supply, which pops the 30A fuse in the consumer unit. Now, you do have some spare 30A fuse wire, don't you?!



    Highly unlikely - just look at the curves for BS 3036 fuses. - a 30A fuse may well carry over 50A for a couple of hours before opening - even if the fusewire was already warm, a few minutes it takes to boil a kettle isn't going worry it (similar for the thermal element of MCBs). The old 100% of the first 10A, 30% of the remainder + 5A for a socket rule has proved it worth for probably many millions of Christmas dinners over the best part of a century - even during the times when my grandmother's generation would boil veg for 20mins at full boil with no lid.

     

    Of course, there is no reason why a Commando socket should not be used.



    Except that it would never physically fit behind the cooker. Ditto for most other 32A+ connectors.


      - Andy.
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    Andrew Jewsbury:


    Highly unlikely - just look at the curves for BS 3036 fuses. - a 30A fuse may well carry over 50A for a couple of hours before opening - even if the fusewire was already warm, a few minutes it takes to boil a kettle isn't going worry it (similar for the thermal element of MCBs). The old 100% of the first 10A, 30% of the remainder + 5A for a socket rule has proved it worth for probably many millions of Christmas dinners over the best part of a century - even during the times when my grandmother's generation would boil veg for 20mins at full boil with no lid.

    I am well aware that fuse wire is conservatively rated so is capable of carrying 150% of its quoted current for over an hour before melting through. However, the apocryphal story doesn't provide any figures for the current consumption of both the cooker and the kettle. It's not unknown for large cooking appliances to be protected with a 30A fuse that really warrant 45A. Users can often get away with 30A during day to day use, but if every element is on full blast and another appliance is plugged into the socket then it's possible that the combined current will be sufficient to blow a 30A fuse.
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    Martin Hutson:

    I believe you now need a dedicated supply for a new cooker installation with its own circuit breaker at the fuse box. There’s also a switch in the kitchen to isolate it when removing or fitting a new cooker. I don’t know why a quick safe dedicated 32amp appliance  connector  wasn’t developed to stop people botching up this. I was horrified to see the original state of the cabling when my kitchen was replaced.





    If I understand this correctly, you are suggesting that all cookers could be connected via a BS EN 60309 plug and socket. (I don't think that the BS1363 plug and socket arrangement is now suitable for loads greater than 10A). If so I might suggest that heavier loaded appliances used inside the domestic environment are better served by direct hard wired connections as these are more likely to be reliable in the hands, or not, of non-competent persons that then might allow for a longer disconnection time for fixed equipment, or even less sensitive fault protection through the use of 100mA RCD/RCBOs



    Legh

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    Martin Hutson:

    Would love to see a BS standard quick connector plug developed to be supplied with new cookers and The corresponding socket in the wall. The state of the cooker wiring in a lot of homes leaves a lot to be desired and think there’s a need for this. It would work a bit like a miniature version of the electric vehicle charging cable. I think with the new modern double ovens that well over 10 amps must be being drawn and overheating cabling with poor connections must be an issue . I think before Brexit it could have been a European standard but l quess this is not going to happen now.




    I'm not sure if there is a long term future in a 32A plug and socket or hard wired cooker switch.


    Is this the shape of things to come?

    https://www.fastcompany.com/90313508/why-top-restaurants-are-getting-rid-of-stoves-and-why-you-might-too


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    Arran Cameron:

    Is this the shape of things to come?




    Not in my house, but there are a lot of people who don't cook, or even claim to be incapable of cooking.

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    I'm not sure if there is a long term future in a 32A plug and socket or hard wired cooker switch.


    Is this the shape of things to come?

    https://www.fastcompany.com/90313508/why-top-restaurants-are-getting-rid-of-stoves-and-why-you-might-too

     





    This is just one specific design concept that could just as well be done with other types of plug in induction hobs, as stated. although, I'd prefer to have them hard wired and in one fixed position next to fire fighting equipment, if needed.

    Induction hobs may well be the way forward as there have been some mention of banning gas fired stoves for the future.

    Now that circuit protection, cables and BS 1363 sockets are at their cheapest there is finanically no need to combine a power socket with the cooker isolator.


    Out of interest, if I placed a steel bar between two induction hob hot plates what might happen?


    Legh
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    Legh Richardson:


    Out of interest, if I placed a steel bar between two induction hob hot plates what might happen?

    Try it and find out! Induction hobs work using the principle of mutual resistance - yes, such a thing does exist in addition to mutual inductance. The pan (or steel bar) functions as both the secondary winding of a transformer connected to a resistive load. The mutual resistance is the value of a resistor that if it replaced the induction coil it would dissipate the same amount of power that the pan dissipates.
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    I don't know that much about mutual resistance between two parallel conductors/cols although I'm aware that you could set up a situation generating negative mutual resistance where the outcome is less than expected.

    I was thinking in terms of the safety aspect, Lets say, leaving a steel serving spoon resting across two induction hobs in the switched on condition. As the plates are only generating inductive current through the pans when they come into contact with the induction plates.


    Seems rather  dangerous to me in the hands of the careless.


    Legh
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    Unlike a steel bar, a spoon would only touch somewhere along the handle and some part of the bowl. There may also be wizard circuitry which might be able to distinguish a pan from a spoon.


    I see from the Smeg literature that the size of the pan and each heating zone should match closely. If true, that rules out any pan which is not circular. If you want to deglaze a roasting tin, how do you do it? ?
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    There may also be wizard circuitry which might be able to distinguish a pan from a spoon.



    The induction hob I have automatically detects the lack of a pan and switches the hob off - so a very large spoon may fool the system, but normally you'd be OK.

      - Andy.

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