CONCORD — Gunshot damage to insulators on a major electric transmission line that runs from Quebec to Massachusetts cost New England ratepayers about $1 million for the replacement power that had to be purchased while the line was being repaired, according to an official with the Vermont company that owns the state’s electrical transmission grid.

Vermont Electric Power Company Vice President Kerrick Johnson said replacing the shot-out insulators cost about $250,000.

The damage posed a serious threat to anyone in the area, he said.

“We hadn’t before seen this level of damage before or consequences this high,” he said.

The transmission line is capable of carrying 10 percent of the electricity used throughout New England.

The damage was discovered last Friday by a crew inspecting the line after the passage of Superstorm Sandy. It took crews two days to repair the damage.

The Caledonian Record reported that 167 insulators were shot out. The case was reviewed by state and federal authorities to determine if it was terrorist-related, but it’s being treated as vandalism.