13A socket fed from 1.5mm twin and earth cable

Depending on the installation method used, the 1.5mm cable has a maximum rated capacity of between 14 and 20 amps, so its right on the limit. As BSEN60898 circuit breakers have a fusing factor of 1.25 to 1.5, then its possible that the the current could increase to 24amp (1.5 x 16) before the MCB would operate under overload conditions. As such the regulations covering overlkoad protection for this circuit have not been complied with. The only solutions are to upgrade the cable to 2.5mm or downgrade the MCB to 10amps.

If the cable is clipped directly to the wall and is not enclosed in any conduit and in free air for its entire run then the regs say 1.5 flat T&E cable is rated up to 20A. However most sparks (including myself) would use 2.5 for feeding a power circuit as you describe it. Easiest way to make it safer is to change the MCB to a 10A version as that's fine for 1.5 cable. Don't attempt to do any electrical work however if your are not competent to do so, call a registered spark in. Thanks Ian