A 230V 4kW load is to be wired in non-armoured single-core 70 "C thermoplastic
insulated copper conductors wired in steel conduit installed on the surface some
25 metres from the distribution board. Three other similar circuits are installed in the
same conduit which passes through an area where the ambient temperature reaches
40 °C. Calculate the cross-sectional area of cable required if protection is by a BS 88-2
fuse. Show all working.