According to the Essential Energy website, the outage occurred shortly after 1pm and continued throughout the afternoon.

Essential Energy Operations Manager for the Macquarie region Jamie Warren said a fault in the network triggered the outage.

"After detecting a fault, our electricity network protection equipment activated automatically, switching power off to 875 homes and businesses in the Dubbo CBD," Mr Warren said.

Faulty high voltage underground cables were identified as the cause of the initial fault, which resulted in a fault current damaging a lightning arrestor on a power pole in Wingewarra Street.

"Crews responded immediately, commence a patrol of the electricity and after ensuring it was safe to do so, restored power to 839 customers at 2:54pm." Mr Warren said.

A second fault was then discovered which caused the second unplanned outage.

"As power was being restored, another fault further along the electricity network resulted in another unplanned power outage for those customers immediately." Mr Warren said.

Crews were able to restore power for all customers in the late afternoon and early evening on Thursday.