The following are the 3 most damaging vehicle element items: a) environment, b) abuse, and c) time. Before even examining them in the context of on-road vehicles, consider a parallel by thinking about the electrical wiring system in any private residence - house. Problems are seemingly always kept to a minimum in a well-maintained home. Environment - mostly at its best, all wiring is in conduit protection in the building walls. Abuse - the greatest common abuse is an overloaded circuit. It results in blown fuses or open circuit breakers. Time - almost indefinite. Problems start when one starts splicing extra wires and "expanding the system" by disregarding electrical building codes. All this results in overloaded circuits, unprotected wires, fire hazards, most of the time, ending in system or building destruction. Now using that above example of the building’s wires, put it in the context of a trailer’s wiring system. Consider the same three damaging elements: ENVIRONMENT Trailers operate on the countries highways twelve months of the year in any weather condition. Winter season puts the trailer wiring systems through the greatest salt attack known throughout history. Eleven times more salt is put on the highways during the short winter season then the total population of the United States puts on the table or uses for food preservation and preparation in a year. Unlike houses that stand still, a moving trailer is under constant and sometimes severe vibration, therefore the wiring system is exposed to the same vibration. During the summer months, the wiring is exposed to the heat and direct sun rays. Environment greatly magnifies any known abuse - mechanical or design. It finds any unprotected wire end or improper splice and introduces salt throughout the wiring system. Result - corroded wire, greatly increased resistance and temperature, all resulting in harness destruction as well as lamp destruction, since salt creep does not recognize any boundaries other than total exclusion. ABUSE The main groups of abuse are: Design Abuse Short cuts in proper choice of wire size. Short cuts in wire schematics by use of numerous splices to save a few feet of wire. "Make shift" splices by twisting wire ends. Copper flash aluminum wire. TIME If the abuse and environment form a team - time becomes the greatest ally in the destruction of a wiring system. It takes but one winter to destroy wiring systems. The above discussed damaging elements set the basic design requirements of proper wiring systems.