The energy provider issued a statement on Friday morning saying two jobs involving pole replacements for the day had been postponed because they have "the potential to extend into the hottest part of the day".

It means one rather than three suburbs, and 33 rather than 98 customers, was affected by electricity interruptions on Friday. The outages were completed by 12.25pm on Friday.

ActewAGL general manager network services Rob issued a further update in the afternoon, saying the planned outage that would affect about 78 households had also been postponed.

"The job was the maintenance of a substation around a school, programmed for the school holidays. We have looked at ways to shorten the job but it’s a large job and the time it will take to complete can’t be shortened," he said in the statement.

"The job would extend well into the hottest parts of the day so we have decided to postpone it, given the current forecast for 39 degrees.

"We are looking at each of our planned outages on a case by case basis as we have been doing all week during the high temperatures. Affected customers will be contacted this afternoon [Friday]."

He said the work would be rescheduled and customers would get at least four working days written notice of the new time.

ActewAGL had previously planned to cut power to parts of three suburbs affecting 98 customers on Friday.

ActewAGL says it has contacted affected customers but refused to release the names of the suburbs, citing privacy concerns.

It says it is doing everything possible to minimise inconvenience.

"Our field crews are starting work earlier, some as early as 5.30am, to complete the planned maintenance work before the hottest part of the day. In saying this we are always very mindful of the safety of our field crews," a statement from it read.

'Confidentiality': ActewAGL tight-lipped on affected locations

ActewAGL will still not reveal which Canberra suburbs will be affected by planned power cuts because of customer confidentiality.

"This decision has been made to protect the confidentiality of the affected customers. And, is therefore a matter between ActewAGL and the customer," ActewAGL general manager of network services Mr Atkin said in a statement issued Thursday night.

The outages will hit as temperatures on Friday reach 41 degrees, the peak of Canberra's unprecedented week-long heatwave and just 1.2 degrees off Canberra's record high.

Overall, more than 300 homes have already been affected by outages over the last two days, with the average downtime between two and half hours to three and a half hours.

On Saturday, 78 Canberrans in one suburb will be without power for part of the day.

In a separate statement issued on Thursday ActewAGL acting chief executive officer John Known said the maintenance was important to ensure the ACT electricity network remains safe and reliable.

"We are doing everything we can to further minimise any inconvenience as a result of planned electricity interruptions," he wrote.

"Our field crews are starting work earlier some as early as 5.30am to get the work done before the hottest part of the day."

ActewAGL's approach is in contrast to South Australian Power Network's decision to call off planned power outages due to the extreme temperatures in the state.

Downer resident Jill Vardy was left without power for more than seven hours from 8.30am on Wednesday, about four hours longer than the average.

She called for a public campaign to change the 'cavalier attitude' to cutting off power, saying the lack of information about the outages had been frustrating.

''I don't know how frail aged people cope,'' she said.

''My health is still affected and the house is still higher than its usual morning temperature today, nearly 24 hours after the cut-off.''

According to ActewAGL, a total of 160 homes across five suburbs were affected on Wednesday, with the average outage lasting 3½ hours.

On Thursday, a total of 158 homes across four suburbs were affected, with the average outing lasting 2½ hours. All four planned electricity interruptions were completed by midday.

Acting Chief Minister Andrew Barr said on Thursday he supported the continued outages, adding that residents would have received notice "well in advance".

He said the maintenance works were necessary to ensure the reliability of the network.

''I'm sure all Canberrans would agree that it is preferable to have planned, short and targeted interruptions rather than widespread, lengthy unplanned outages," he said.

ACT Emergency Services Agency Commissioner Dominic Lane also voiced his support for the outages, saying the provider had been proactive in ensuring the maintenance programs were completed in the early parts of the days.