Vandals left more than 1,000 residents near Ballymena without electricity.
They broke into a station for distributing power to homes on Tuesday night and damaged equipment, locks and signs with a hatchet as well as cutting down and burning an electricity pole.
Householders in Ballykeel and the Larne Road were left without supplies. Most were restored within half an hour but some had to wait until the early hours of Wednesday morning.
Roy Coulter, safety manager at Northern Ireland Electricity (NIE), said: "Thousands of volts of electricity run through this equipment and the cable every second so the risk of electrocution was extremely high.
"We cannot stress strongly enough the danger of this type of deliberate damage.
"Those involved should consider themselves lucky that they weren't seriously injured or even killed."
NIE teams have re-secured the station and repaired the damage.
This is the third time that equipment in this area has been targeted.
© Press Association