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60A main Fuse, should I upgrade?

Former Community Member
Former Community Member

Supplier main Fuse is 60A and current consumer unit has 80A RCD (61008) as isolator with a notice saying 'Max load not to exceed 80A". Property is one storey with 5 rooms. Currently have 8 circuits, 2 lights with B10s, 2 ring finals with B32s, Cooker with B40, Shower with B40, Water Heater with B16 & Garage feed to a sub board with C40. Want to add a new 10.5kw shower so will need 50A protective device but not sure if should be approaching the DNO for an upgrade of the main fuse as running both showers together alone will draw a decent load

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    Consider the blow/no blow curves for the 13A plug fuse on the graph below.

    Normally we only consider the right hand limit of the all-blow curve, but for any fuse it would have a form generally rather  like this. For the 13A fuse, note the vertical asymptote for the long term overload, could be between 20 an 25 amps for ever, while say a 100A fault may blow a 13A fuse as fast as 0.01 sec or as slow as 0,3 seconds.

    Note that for these small fuses, even 10msec is not adiabaticlly fast, and the curve has not yet settled to an I2t form.

     

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  • 0

    Consider the blow/no blow curves for the 13A plug fuse on the graph below.

    Normally we only consider the right hand limit of the all-blow curve, but for any fuse it would have a form generally rather  like this. For the 13A fuse, note the vertical asymptote for the long term overload, could be between 20 an 25 amps for ever, while say a 100A fault may blow a 13A fuse as fast as 0.01 sec or as slow as 0,3 seconds.

    Note that for these small fuses, even 10msec is not adiabaticlly fast, and the curve has not yet settled to an I2t form.

     

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