Factors That Affect the Resistance and Safety of Wire

Physical Damage

Electrical wires undergo damage over time. Wear and tear strips insulation away and can even tear the wire completely in two. You should inspect electrical wires regularly for frayed insulation and exposed wire. In addition, frayed electrical wire should not be allowed to touch other wire. Electricity travels in a circuit. For example, it travels from the power box inside a wall outlet, through one wire in the appliance's power cord, through the electrical component and back through the other wire. If two bare wires touch when current travels through them, it creates a short circuit that will destroy the wire and could cause a fire.

Wire insulation is rubber due to its ability to bend and twist, in addition to its electrical resistivity. The actual electrical wire is most often made of copper, but other metals can substitute; one of the most common is aluminum. Aluminum wire has lower conductivity, meaning that it can't carry as much current, but is lighter and costs less. Aluminum has a lower melting point and is prone to overheating.

The resistance of electrical wire depends on its physical dimensions. If you take two wires and connect them to the same power supply, the shorter, thicker wire will have more conductivity. Electrical currents, which are carried by electrons, lose their strength over longer distances because of friction with the edges of the wire and with other electrons. Similarly, a thinner wire causes the electrons carrying the current to constantly rub against one another and lose energy to friction because the electrons are crowded in a tighter space.

If electrical wires are poorly connected to a power source or the component load, the electricity cannot travel as effectively. Less surface area of electrical contact has the same effect as sending the current along a narrow wire: friction between electrons causes the material to heat up. If the wire has any breaks, a strong current will jump between the two broken ends and heat the air due to electrical breakdown, or stripping electrons free of atoms to create an ionized pathway.