Hi jetset, WF103 is very stiff and doesn't like tight bends. If you feed it in under concrete interlocking tiles or slates, your house insurance may well be invalidated, in the event of you claiming for storm damage, also rain and wasps can get in. For my money, you would be better off bringing it in through the board, with a good loop in it to stop water tracking in. Consider using loads of electricians' silicone grease in the connecting plugs and sockets (GPO and BT use this in their crimp termination nipples, as it prevents atmosphere and damp getting to the metal).
