An engine bay is a harsh environment for a wiring harness. Temperatures over 100C, vibration, movement of the engine, water, oils and solvents and that is just under normal running conditions. There are also accidental pulls on the cables & connections and impacts of tools onto the cables when servicing. Just one electrical short, poor connection or broken cable is all it takes to stop your engine but you should never have to worry about this as they can all be easily avoided; you just need a wiring harness that is up to the job! Please see available wiring looms from Omex Technology: