How would three-hour power cuts work if enacted in Great Britain?

theguardian.com:

People in England, Scotland and Wales are braced for the possibility of rolling power cuts this winter after a warning on Thursday from National Grid. The electricity and gas system operator has said households could face a series of three-hour power cuts if Vladimir Putin shuts off gas supplies from Russia, and Britain experiences a cold snap akin to 2018’s “beast from the east”.

Although National Grid has labelled the scenario “unlikely”, the emergency plan has prompted memories of persistent power outages in the 1970s and brought into focus the process by which people are cut off.

The system of rota disconnection, or rota load-shedding, is designed to equally share out the available power in a country or region through strategic shutdowns. In Great Britain, consumers in different parts of the country would be notified a day in advance of a three-hour block of time during which they would lose power. Households in different areas would then be cut off at different times or days, with the frequency rising depending on the severity of the supply shortage. The process is in legislation under the Electricity Supply Emergency Code.

There are 14 licensed areas of the country; within these, there are smaller areas on different circuits that have a timetable for cutoffs. The aim is to reduce power usage by about 5% through the three-hour disconnections. Consumers would typically be notified with a text message, similar to when there is a planned outage for maintenance work. An emergency public information campaign by National Grid and the government would be deployed across radio, billboards and social media platforms to urge people to use less energy. Liz Truss has so far resisted calls to ask people to use less energy.

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