A seller of residential property must have at least two residual current devices, or RCDs, installed before the sale is completed. An RCD is a safety switch that cuts the power when it detects a fault.

Mains powered smoke alarms must be installed as well, which means hard wired rather than battery only.

Before settlement the seller should give the buyer a certificate from a licensed electrical contractor confirming both are installed. There is no obligation on the seller to provide one unless the contract requires it, so a buyer who wants proof has to arrange the inspection.

See RCD and smoke alarm rules for WA sellers for what it costs to get this wrong.