Any wiring or plumbing attached to equipment that vibrates is subject to chafe. Eventually this chafe leads to leaks, electrical shorts, and all sorts of dire consequences. It is better to find the potential chafe points before they become a problem.
Basically, anytime you have two surfaces touching, where there is movement, some form of chafe protection should be applied.
For years we’ve used a simple remedy – split hose over chafe-prone items. In the photo above we have a shut-off valve in an engine hot water circuit. There are hose clamps on each side of the valve, and these will eat into the salt water hose over which they ride. So, a section of split hose has been inserted around the offending section. This will protect the salt water hose below, to which the heater hose, valve, and chafe gear are wire-tied.
Here’s another example. This time a diesel fuel feed line is running over a structural beam. The outer section of bilge pump hose will absorb any chafe that occurs.
In this case there are several things going on. First, a section of split hose has been inserted over the flange of the hull girder. This protects both the wiring (in its own chafe protection to the left) and the section of hose running vertically off the engine centered in the photo.
Wiring that is not fastened to specific chases should always be run inside of some form of insulation. The corrugated material shown here is available in most electrical supply stores.