The provisions of this section of Part 3 in the 2002 BSS Standards are mandatory for non-private boats where applicable.
It's a good idea to keep cables that are insulated or sheathed in PVC away from polystyrene thermal insulation - the two materials have been known to react and break down the cable covering. It's recommended that the electrical installation is periodically checked by a competent electrician - preferably every year - so that you can keep a record and spot the signs of a problem, before it becomes a potential hazard. [3.4]