- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 13 Dec 2022
 What is a power cut?
Power cut, loss or interruption of supply and blackout all refer to an event in which there is a planned or unplanned break in the supply of electricity to a region, area, or building. Such events can be localised and unplanned, effecting single or groups of dwellings, such as when supply cables or pylons are damaged, or if centralised infrastructure is damaged they may affect large areas. They may also be a planned strategy of supply.
Power cuts were quite common during the second world war in London and other towns due to damage inflicted on infrastructure and more recently in certain areas of Ukraine as a result of the war with Russia as part of strategic military action. New York was affected by a number of blackouts in 1965, 1977 and in 2003, caused by component and software failures, whilst the blackout of 1977 was caused by a lighting strike at Buchanan South, resulting in a blackout across the whole city which led to criminal activity including looting. In the UK during 2015 and 2016, storm Frank lead to damage and flooding leaving 40,000 homes without power.
 Planned reductions
In some cases power cuts may be planned by an electricity supplier or by the national grid as a way of managing supply, where demands peaks or where demand outstrips supply. This can result from a number of different causes but common circumstances might be extreme weather events or temperatures, or problems with fuel supplies.
In February of 1972 the Central Electricity Generating Board in the UK told its consumers that some households would see power cuts lasting up to nine-hours, as a result of miners strikes across the country leading to a dramatic reduction in coal available for power stations. A three day week was later introduced between December 1973 and March the following year, which was planned to limit the consumption of energy by commercial users, who were limited to only using three days worth of energy a week. Other countries have experienced blackouts such as the US and Canada for 2 days in 2003 and 2004 and in many other countries blackouts are a daily occurrence.
During the Financial Times’s Energy Transition Summit in 2022, John Pettigrew head of the National Grid warned British households that blackouts may be imposed between 4pm and 7pm on “really, really cold” winter weekdays if European gas exports were cut. The comments came after the National Grid set out several “unlikely” scenarios in which Britain would run low on supplies but noted that it had not changed its “base case” and there would be sufficient gas and power to meet demand in Britain this winter. Pettigrew said “In the context of the terrible things that are going on in Ukraine and the consequences of that [it was] right that we set out what some of the potential risks could be”, he noted that electricity and gas may be switched off on “those deepest, darkest evenings in January and February” if energy supplies from Europe prove insufficient.
- Storms: Extreme weather such as storms, heat waves, snowfall and ice as well as rainfall and flooding are the most common causes of widespread power outages. Lightning strikes on electrical equipment, transmission towers, wires and poles can also lead to outages in grid systems.
- Damage: Fallen trees (from extreme storms), human error (such as road works), as well as sabotage (during war), accidents ( such as vehicle collisions), and wildlife can also on occasions cause damage to cables.
- Earthquakes: Relatively rare in the UK but in many parts of the world earthquakes can disturb and damage electrical facilities, power lines and supplies.
- Demand outstrips supply: Heat waves or dark cold snaps can overburden electrical systems leading to unintentional as well as intentional outages. This may become more common if there are long term supply issues.
- Alternating current and direct current
- Battery storage.
- Community energy network.
- Electrical power.
- Electricity supply.
- Energy consumption.
- Energy storage.
- Kilowatt hour.
- Power generation.
- Power surge.
- TV pickup.
- Uninterrupted power supply for buildings.
Featured articles and news
From the basics to the future from our Cohesive BIM wiki.
As electrical sector feels skills shortage bite.
CIOB Academy’s course take-up inked to external factors.
Q and A with self-representing artist, Hannah Shergold.
And publishes three-year strategic plan.
Introducing changes to make it more effective from 2024.
Shortlist announced for 2023 public choice award vote.
The last of the Victorians. Book review.
An exotic name that is shrouded in mystery.
Fropm practice to research and the business of materials.
Terms, histories, theories and practices.
Alteration and everything else before demolition.
And CIOB's response.
Presidential update from CIAT's Eddie Weir PCIAT.