(N/A) In household wiring,$Cu$ (copper) or $Al$ (aluminium) wires are used based on the criteria of cost,conductivity,and weight.
$1$. Cost: Copper is significantly more expensive than aluminium.
$2$. Conductivity: Both are excellent conductors of electricity,though copper has slightly higher conductivity.
$3$. Weight: For a given length and resistance,aluminium wire is much lighter than copper wire.
$4$. Practicality: While silver is a better conductor,it is prohibitively expensive. Iron is cheaper but prone to rusting and has higher resistance,making it unsuitable for long-term household use.
Therefore,aluminium is often preferred for its balance of cost-effectiveness and conductivity.