It is the second time in seven days that national grid has issued the warning, known as a notice of insufficient system margin (NISM). However on both occasions the notices were swiftly canceled as additional generation capacity was brought on stream.
The alert was issued to cover a shortfall of 300MW over four hours on July 26. The hot weather has caused a major increase in demand for electricity to serve fridges and air conditioning units. This spike has been exacerbated by power plants being shut for maintenance or repairs, among them the coal fired station at Ratcliffe-upon-Soar, operated by E.ON.
