Managing director Peter White said the outages have resulted from ash shorting out power lines.
But some blackouts have resulted from lightning strikes that were generated within the towering columns of ash soaring high above the eastern Caribbean island.
Ash has recently fallen over the small portion of the island still safe to inhabit, especially in Olveston and Olde Town.
Montserrat Volcano Observatory director Paul Cole said a small pyroclastic flow of super-heated debris reached the ocean as part of Soufriere Hills’ dome collapsed.
The volcano roared back to life in 1995, killing 19 people and destroying much of the British territorial island.
About half of its former population of 12,000 moved permanently to other islands, Britain or elsewhere following the disaster.
Photos: Montserrat Volcano Observatory