Fuses for showers.

Sparkingchip over 5 years ago

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 AJJewsbury over 5 years ago

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.

Isn't it just down to 40A not being a preferred size for BS 1361/BS88-3 fuses? - normally your choice would either be 30A (BS 1361)/32A (BS 88-3) or 45A.

- Andy.
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0 AJJewsbury over 5 years ago

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.

Isn't it just down to 40A not being a preferred size for BS 1361/BS88-3 fuses? - normally your choice would either be 30A (BS 1361)/32A (BS 88-3) or 45A.

- Andy.
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Fuses for showers.

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