The Australian Energy Regulator imposed the fine on Evoenergy in February this year, related to three "type one" breaches last year.

It was the second such fine the regulator has issued to Evoenergy in the past year, after the company another customer with life support equipment unexpectedly lost electricity supply in August last year, leading to a $20,000 penalty for Evoenergy.

Under the AER's rules, electricity distributors must give any residential customers running life support machines at least four days notice of a supply interruption, but Evoenergy, formerly ActewAGL Distribution, failed to give the required notice to the customers.

AER chairwoman Paula Conboy said it was imperative customers relying on life support equipment were given advance notice of any planned interruption to their electricity supply, to make alternative plans, as any unexpected loss of supply could have "dangerous, and even fatal, consequences".

A spokeswoman for Evoenergy said the distributor's advanced distribution management system, which generates customer notifications of planned interruptions, had failed to generate the notifications in two cases, and an "administrative error" led to a letter not being generated for the third case.

The three instances related to three properties with a total of four customers on life support.

But the spokeswoman said the distributor had since spoken with each life support customer and apologised, and the customers have said the outage "did not pose a safety concern and they were not negatively impacted by the planned outage".

Evoenergy has paid the fine and has agreed with a regulator requirement to review and improve its supply interruptions identification and notification processes by the end of this calendar year.

While the distributor had to pay the fine, the payment was not an admission of a contravention of the regulator's retail rules.