Several factors make aluminum wiring dangerous. The three most noteworthy factors are Heat, Expansion/Contraction, and Oxidation. These factors can create problems on their own however; they may all contribute to the problem. The main problem is heat and in every case, heat compounds the problem.
EXPANSION AND CONTRACTION
Aluminum wire expands and contracts at different rates than other metals used in electrical systems. Electrical current causes a change in the temperature of the wire. The heaver the load and or smaller the wire, the more the temperature changes. These changes in temperatures can cause joints to loosen and compromise the connection.
A compromised connection creates additional heat. The additional heat contributes to the problem and the problem starts to snowball. The heat created is sometimes sufficient to start a fire! Even if this does not directly start a fire, the heat can melt and or burn away insulation, which can create a short that may arc. Electrical arcs often reach temperatures in excess of 10,0000 Fahrenheit.
OXIDATION
Aluminum oxidizes. Oxidized aluminum wire or wire covered with aluminum oxide is a very poor conductor. Once again, we are dealing with a compromised connection and as above compromised connections can create heat. Heat compounds the problem and things get worse each time a load is re-applied
There is a reason why it no longer used its called fires. I cant say this enough never use aluminum wire !!!!!
