I am moving skirting boards upwards by 1 inch. Sockets are set in the wall just above the skirting, so they must be moved up by 1 inch too. I am hoping there will be enough slack in the existing cables (which are buried in the concrete floor) to allow for this. If not, what do I do? Can I make a short extension to the cable tails within the mounting box? If so, what is the recommended method? Thanks for your help!