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Electrical

Wylex 30 amp fuse carrier box

Anonymous user 03/03/2024 - 3.01 PM

My uncle has a very old house with only two main fuses and a Wylex 30 amp fuse carrier box for the old 7 kW electric shower with 10 mm cable to the double pole isolating switch. He's been told that because he doesn't want to go to the expense of having a new consumer RCB unit fitted, and the wiring is rated more than 40A, it's possible to fit a 40A fuse in the Wylex box in order to fit a new 7.5 Kw shower. Is this true?

Are you a tradesperson and able to answer this question?

1 Answer

Electrical Safety Services

Rating: 5 out of 5

Dereham

The main issue is the lack of RCD protection. All shower manufacturers require their electric showers to be RCD potected (its clearly stated in the instruction manual that comes with the shower). This is because the 17th Edition wiring regulations were revised in 2008 and in order to be compliant an RCD must be fitted. For a 7.5kw shower a 32amp BS1361 fuse carrier could be used to replace the old 30amp fusewire type fuse. As the shower is 7500watts, when divided by the supply voltage of 230v the current drawn is around 32.6 amps. Therefore a 40amp fuse is not really required. If you were going to fit an 8.5kw/9Kw shower then yes a 40amp fuse would be required. However as I say your main issue is the lack of RCD protection, which if not fitted may well invalidate the warranty on the shower, not to mention being non compliant with BS7671:2008. Any alteration to the shower circuit will need to be carried out by a Part P registered electrician and notified to local building control (see link below for more information) http://www.donttakethep.co.uk/

Answered5 August 2013