The failure of a piece of electric equipment known as a hot line clamp knocked out power for 1,400 customers in Hopkinton on Tuesday afternoon, including Harold Martin School.

The problem occurred around 1 p.m. and was fixed by 2:30 p.m. Students stayed at the school, which serves kindergarten through grade 3, and went home at the usual time.

Eversource spokesperson Kyle Costa said the outage occurred when “a hot line clamp – a metal connector between two wires — failed and our crews worked as quickly and safely as possible to replace it.”

One sign of the outage was the influx at the town library of a number of people who work from home.