The unidentified man, hailing from Kerala, was employed with Jaiprakash Associates at Punatsangchhu Hydro Power Project in Kamichu of Wangdue division.
The incident happened on Sunday when he was drilling hole with two other Indians at a powerhouse's vertical pressure shaft, Kuensel online reported.
He was rushed to Jaiprakash hospital in Kamichu after the accident, but died on the way, the report said.