Question

Residential building codes typically require the use of 12-gauge copper wire (diameter 0.205 cm) for wiring receptacles. Such circuits carry currents as large as 20.0 A. If a wire of smaller diameter (with a higher gauge number) carried that much current, the wire could rise to a high temperature and cause a fire.

(a) Calculate the rate at which internal energy is produced in 1.15 m of 12-gauge copper wire carrying a current of 20.0 A.

(b) Repeat the calculation for a 12-gauge aluminum wire.

Explain whether a 12-gauge aluminum wire would be as safe as a copper wire.

Answer 1

a)

Power dissipation at a resistor R carrying current I is,

Now,

b)

Therefore, Copper is safer than Aluminium as copper dissipates less energy than Aluminium.

For the same amount of current, the heat dissipation is directly proportional to the Resistance of the wire. The resistivity of the Copper wire is less than that of Aluminium; making is safer.