Using aluminium busbar/cables in an aircraft instead of copper I have just found out Airbus uses aluminium wiring in the A380 to save weight. However, I didn't see anything about whether all the wiring is aluminium, or if copper wiring is also used. What is the logic behind this, and do other aircraft manufacturers do the same? Does Airbus use aluminium wiring in aircraft produced since the A380 was introduced? Are there any risks associated with using aluminium wiring on aircraft?
While it is true that copper is 1.6 times more conductive than aluminum per volume, 


  Conductivity in $\frac{\mathrm{MS}}{\mathrm{m}} = \frac{\mathrm{10^6}}{Ω\,\mathrm{m}}$:
  
  
  copper:    56
  aluminium: 36
  $$\frac{56}{36} = 1.56$$
  


aluminium is 2.1 times more conductive than copper per weight.


  Density in $\frac{\mathrm{g}}{\mathrm{cm^3}}$:
  
  
  copper:    8.96
  aluminium: 2.7
  $$\frac{36 \cdot 8.96}{56 \cdot 2.7} = 2.13$$
  


Another important metric concerns the cost. The conductivity per cost is 7.1 times higher for aluminium. 


  Base metal price in $\frac{\mathrm{US$}}{\mathrm{lb}}$ (as of today):
  
  
  copper:    2.71
  aluminium: 0.81
  $$\frac{36 \cdot 8.96 \cdot 2.71}{56 \cdot 2.7 \cdot 0.81} = 7.14$$
  


Aluminium wiring is safe if it is sized and terminated correctly. In comparison with copper, aluminium is softer, shows more creep, and has 30% stronger thermal expansion.