The incident occurred this morning when three workers had climbed a tower at the sub-station, as part of daily maintenance and were suddenly thrown to the ground, due to passage of electricity, they said.
While Ramu (30) died on the spot, Santoshkumar (32) and Meghanathan (33) sustained serious burn injuries and were admitted to the government hospital here.
Investigations are on, they said.
The board has ordered a departmental inquiry into the incident.