25,300 homes were cut off after what witnesses describe as an explosion at an electricity substation in Saltburn.
Video footage shows fire and sparks at the station at just before 7 o'clock on Monday night. No one was injured.
Power was restored to 22,000 customers within half an hour and to many more through the night.
353 homes are still without power. Northern Powergrid is working to install generators to restore power to those homes by 10 am.
A customer service team has been in Saltburn all through the night to give advice to those without power.