That shower cable was discovered during an EICR that I did last December. Curious as to how Mr. Wetpants managed to install a cable supplying a shower circuit within a modern property with sheeted flooring without damaging any of the plasterboard walls, I decided to trace the cable run. Upon rolling-back the carpet at the top landing, I realised that the imbecile had simply drilled a hole between one of the steps to inside the cupboard on the ground floor where the consumer unit is located. He then ran the cable across the stairs and up to the top landing whereupon he drilled a hole through the top step to gain access beneath the landing floor. Further holes were then drilled in the landing flooring so he could guide the cable towards a linen cupboard. Once inside the cupboard he ran the cable up into the loft and across to a 45 amp pullcord switch. Naturally, the numpty left the cable dangling inside the linen cupboard.
Fortunately, because the property owner hired a joiner to replace the sections of damaged flooring, the job of rewiring the circuit and upgrading the cable to 10mm was made considerably easier. No RCD protection was provided for the circuit so a consumer unit upgrade was also required. All in all, a very profitable discovery indeed!