Cables can overheat if the cabling on your boat is not sufficient to carry the
current. To minimise this risk the cables must be capable of carrying the current
and be of the right construction and grade. New electrical installations must use
multi-stranded conductors, since solid conductors can easily break where there
is high vibration or repeated flexing of a cable.

If solid conductor wiring is already fitted this is acceptable, as long as it's
securely supported and shows no sign of wear and tear. It's a good idea to
include a check on the condition of all of your boat's wiring during routine
maintenance and inspection.

Fuel, water, heat, oils and other chemicals can all cause damage to your cables,
reducing the effectiveness of the insulation and increasing the risk of cables
overheating - which could cause them to short-circuit, spark and start a fire.
Exposed 240V wiring can also give people on your boat an electric shock. To
reduce these risks all cables must be properly insulated and/or sheathed with a
resistant material.

To prevent damage caused by vibration, cables must be securely fixed at
approximately 300mm (12ins) intervals, or run in a pipe or trunking which is
adequately supported. Also, to reduce the chance of damage to the cables, they
must be kept away from other heat sources such as exhaust outlets, cookers
and stoves. [3.2]

Upon entering the lock a slight impact with the lock wall caused the battery to slide and the battery terminals to make contact with the metal coaming of the hull. The hull became live. Via the engine bearers the electric current travelled along the metal braided fuel supply and return lines. Where these hoses touched, sparking occurred and the fuel hoses burnt through, allowing diesel spray to create a vicious fire. It took the fire brigade 20 minutes to extinguish the fire. [3.1] From a report detailing a serious engine compartment fire on a hired narrowboat.