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Can a new hob that is drawing 33.4 amps be supported by a 32 amp mcb?

I've been asked to investigate why a 32 amp MCB is tripping on a newly and proffessionaly installed Hob which is actually drawing 33.4 amps (clamp tester used). All cabling on the 6yr old new build is as per current regs.
The only thing I've noticed and got from the customer is that the cooker point switch can buzz unless she pushes the switch down firmly.

2 Answers from MyBuilder Handymen

this hob needs to be supplied with 10mm twin and earth with a 40 amp mcb RCD protected or RCBO, also it needs inspecting, testing and certificating and the work notified to LABC by a "Part P" registered electrician.


Answered 24th Sep 2012

Sounds like a loose connection at the switch causing a high resistance, and hence more current to be drawn.

As most BSEN60898 type b circuit breakers have a fusing factor of 1.25 a 32amp MCB would trip on overload at about 40amps, so its strange that its tripping at around 33amps.

Rather than rewire the circuit with 10mm cable its best to change the cooker switch first and see if that makes any difference and if not then replace the MCB for a 40amp type b.


Answered 20th Jan 2013

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