What size electric cable is required for an electric shower?

The size of cable that can be used for an electric shower depends on a number of factors which includes, the kilowatt rating of the shower, the method of cable installation, any de-rating factors and the length of circuit. In some cases 6mm cable will be adequate for a shower rated up to 8kW. For showers above 8kW it may be necessary to install 10mm cable. In order to comply with Part P building regulations a competent installer familiar with the requirements of the current I.E.E regulations must assess the proposed circuit in order to select the correct cable size.