Electric Cooker Radial MCB Size

stl

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Hi,

Could someone advise if the MCB is the correct size for the installation below.

- Cooker radial circuit on 6mm T&E cable direct from the CU with a B40 MCB and RCD on circuit. Cable is under floorboards, loose and less than 15m in length. Cable feeds a CCU with socket and then a cooker connection unit from where a cable connects to the back of the cooker. Approx 1m of cable is buried in plaster. The total load of the cooker is 10085W.

- The reason I ask is that the shower in the same property and on its own circuit was replaced recently and MCB downgraded to B32 for a 6mm cable and 8.5kw shower.

Thanks in advance for replies.
 
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Yes, the cooker is alright.

In fact 32A would do for the cooker as it has several elements which do not all come on at the same time.


However, the shower being a single load should have a 40A MCB BUT it must be ascertained that the cable runs through NO thermal insulation nor conduit.
It would appear strange to reduce the rating of the MCB unless it was to protect the cable but then it (the MCB) is too small for the shower.
 
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Thanks - So is 40A on the cooker ok, i.e. still safe if a 32A would do?

The shower has approx 1m of cable buried in the plaster behind plastic cladding, so maybe thats why they changed to 32A. Did get a certificate after all. Cooker is an existing installation.
 
Thanks - So is 40A on the cooker ok, i.e. still safe if a 32A would do?
Yes, if the cable routing is as you said.

The shower has approx 1m of cable buried in the plaster behind plastic cladding, so maybe thats why they changed to 32A. Did get a certificate after all. Cooker is an existing installation.
If it is buried in plaster that's fine for 47A so 40A MCB would be satisfactory.

Are you sure they didn't change the wrong one?
 
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My 8.5kW shower is protected by a 32A MCB also. All I know about the cable is that it runs between my ceiling and the floor of the flat above.

I guess if the shower is drawing 35.4A, it takes somewhat more than 32A for the MCB to consider it an overload.
 
My 8.5kW shower is protected by a 32A MCB also. All I know about the cable is that it runs between my ceiling and the floor of the flat above.
It is not compliant.

I guess if the shower is drawing 35.4A, it takes somewhat more than 32A for the MCB to consider it an overload.
It will (should) never trip at 35.4A.

The MCB is just likely to get hotter than it should in normal use and eventually 'wear out' although for the normally short time of a shower it probably won't do much damage.
However, it is not correct.
 

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