Work has begun to clear away mud and rubble that damaged a substation at Lyttelton following a mudslide on Wednesday.
The Orion substation supplies power to 1000 customers, including Port Lyttelton.
Orion says work will begin on stabilising the building when geotechnical engineers have minimised the risk to the substation.
Power supply in the area is so far not affected.
Orion chief executive Rob Jamieson says strengthening work several years ago prevented the damage from being worse than it is.