New London — The city’s fire marshal has ruled that the cause of the May 5 fire that damaged the recently opened Lighthouse Inn was accidental.

New London Fire Marshal Vernon Skau said an investigation determined the fire was sparked by a contractor drilling holes for the placement of a new Lighthouse Inn sign at the front of the building. The contractor used a concrete bit on the drill that, once through the exterior stucco, hit wire mesh that is part of the plaster and lathe interior walls. The heat from the friction caused by the drill bit, “much like rubbing two sticks together,” sparked the fire in the insulation inside the wall, Skau said.

The fire had struck the local landmark shortly after owner Alwyn Christy had reopened the bar and restaurant on the first floor of the building. The fire was contained to the second and third floors, where Christy has plans to renovate the two dozen guest rooms.

The City Council on Monday approved a $75,000 grant to aid in the reconstruction of the building. It was one of three grants approved by the council under the city’s beautification and historic preservation program funded by the federal American Rescue Plan Act.

g.smith@theday.com