Electrical Wiring: Conductors are measured by American wire gauge (AWG) for smaller cross section, and circular mils (kcmil) for larger cross section. All electrical conductors have some resistance to the flow of electricity, and electric current flowing through them causes voltage drop and power dissipation, which heats the wire. Electrical wiring is made up of very conductive metals like aluminum and copper witch can conduct a large amount of current before melting, but long before the conductors melt, their insulation would be damaged by the heat.
Aluminum: Aluminum wiring, used in some homes from the mid 1960's to the early 1970's, is a potential fire hazard. Aluminum conductors have more resistance, lower cost, and weigh less than copper conductors. Aluminum can creep, slowly deforming under load, eventually causing device connections to loosen, and also has a different coefficient of thermal expansion compared to the materials used for connections. According to the U.S. Consumer Product Safety Commission, fires and even deaths have been reported to have been caused by this hazard. Problems due to aluminum wiring expansion, or much more likely micro-fretting and arcing at the aluminum wiring connectors, can cause overheating at connections between the wire and devices (switches and outlets) or at aluminum wire splices. The connections can become hot enough to start a fire without ever tripping a circuit breaker! Aluminium has 61% of the conductivity of copper. The cross sectional area of an aluminium conductor must be 56% larger than copper for the same current carrying capability.
Copper: Copper conductors are usually found in electrical devices because of their very special properties, which make them very practical for use. Copper conductors have high electric conductivity, ductility, tensile strength, thermal conductivity, creep resistance, corrosion resistance and electrical overload resistance. Today, copper conductors used in building wire often exceed the 100% IACS standard. Copper does not creep or loosen at its connections. Nearly all electrical devices rely on copper wiring because of its multitude of inherent beneficial properties. At junction boxes and at terminations, for example, copper can be bent, twisted, and pulled without stretching or breaking.
Re-wiring: Re-wiring a property involves pulling out the old wires and installing new ones. Re-wiring electrical system provides an excellent opportunity to increase the number of outlets and lighting fixtures, it also ensures personalís safety and increases propertyís value by bringing it up to modern building codes.