WA’s power utility has been fined $75,000 over an error.

Western Power was hit with the fine over its “systemic failures”, after a connection error caused three Perth homes to have dangerous levels of live electricity.

Western Power workers were replacing a power pole in Yokine in February 2018, disconnecting then later reconnecting the electricity supply for nearby properties.

A worker who had no formal training on multiple master meters connected the line neutral cable to the wrong location. This left three homes with live power at an excessive voltage, resulting in almost $5,500 damage to appliances.

Western Power pleaded guilty to breaching the state's electricity regulations, and was charged in Perth Magistrates Court.

The authority says it has implemented changes since the incident, but the magistrate factored in other historical breaches, and found that management should have addressed systemic failures in training, supervision, processes and testing procedures.