An Oakland man fell to his death Monday while working on an electrical transmission tower off Boom Road.

The U.S. Occupational Safety and Health Administration is investigating the circumstances that led to the death of John R. Plante, 44, of Oakland.

Plante was working high on one of the poles that are part of a Central Maine Power Co. line upgrade in the area when he fell about 55 feet just before 4 p.m., said Deputy Police Chief Jeffrey Holland.

The workers typically wear safety harnesses, Holland was told, but it’s not clear what caused the fall.

“It appears to be an accident with tragic results,” he said. “He survived the fall but by the time they got him to Maine Medical Center shortly after, he passed away.”

Emergency medical crews were hampered by the remote location of the pole, more than a quarter-mile from the road, Holland said. The fire department’s off-road vehicle was used to take him to the waiting ambulance.

The state medical examiner will investigate the death and OSHA will seek to determine what precautions should have been taken to prevent the fall.

CMP is working on a $1.4 billion upgrade of its 350 miles of transmission lines that run from Orrington to the New Hampshire border. The project involves building a new set of 345-kilovolt towers, like the large wooden structures that are visible from Interstate 295 north of Topsham.

Plante worked for a subcontractor, Hawkeye LLC, based in Hauppauge, N.Y.