Waterford — Off-site power was restored early Sunday afternoon to Millstone Power station’s reactors 2 and 3, after they had shut down at 7:15 a.m. due to a loss of off-site power.

Nuclear Regulatory Commission Public Affairs Officer Neil Sheehan said “all safety systems functioned as designed, and there are no impacts on public health and safety.”

He said the plant’s emergency diesel generators were activated, providing power to safety systems until the off-site power was restored.

He added Connecticut Light & Power has determined that an electrical fault in a 383-kilovolt power line to the Millstone switchyard was likely the cause of the loss of off-site power.

The shutdown was deemed an “Unusual Event” — the lowest of four levels of emergency classification used by the NRC.

Sheehan said the NRC was promptly notified of the reactor shutdowns and it dispatched a resident inspector assigned to Millstone to the plant to independently verify the safe shutdown of the units and oversee the restart planning.