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Fuses for showers.

Sparkingchip
From a electric shower installation manual:


Circuit Protection Table

Circuit Protection Device


Unit Rating (@ 240V)

8.5kW

MCB 40A

Cartridge Fuse 45A


9.5kW

MCB 40/45A

Cartridge Fuse 45A


Why a 45 amp cartridge fuse for a 8.5kW shower or for that matter even the 9.5 kW shower?


I presume it must be time related as the 8.5 kW shower will only load a 40 amp fuse to around 90% of its capacity.


How long can cartridge fuses be run at 90% capacity for?


 Andy B.
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  • 0
    When I did the 16th edition course the lecturer said the authors of BS7671 like cartridge fuses as they are very predictable and there’s not any chance of mechanical failure, so you know what to expect from them.


     Andy B.
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  • 0
    When I did the 16th edition course the lecturer said the authors of BS7671 like cartridge fuses as they are very predictable and there’s not any chance of mechanical failure, so you know what to expect from them.


     Andy B.
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