Energy shortages

Power cuts because of an energy shortage are rare. They would happen if there’s not enough power being generated to meet the demand of homes and businesses across the country.

Power cuts can happen for a variety of reasons all year round. The most common cause of a power cut is someone damaging a power cable in the road. Since 2015, the number of power cuts has fallen by 10% thanks to investment in our power networks. Learn more on our ‘what causes a power cut’ page.

National Grid ESO (Electricity System Operator) is responsible for making sure there’s always enough power being generated to meet the needs of customers. This is known as keeping the energy system ‘balanced’.

When there’s too much demand for electricity and not enough electricity being generated, it might be necessary to switch power off to homes and businesses. This is a last resort.

Before power is cut off, National Grid ESO will:

  • Ask for more power to be generated

  • Ask large businesses to reduce how much power they’re using

  • Paying customers to use less energy at times of need

Find out if you can be paid to use less energy at times of need by speaking to your energy supplier. Ask them to tell you more about the Demand Flexibility Service.

What happens?

If there is a need for power cuts because of an energy shortage, power cuts would be shared across the country. This helps to reduce how much power Britain needs without switching everyone off at once.

It’s likely these power cuts will be publicised widely on social media and mainstream news channels, such as BBC News. Because misinformation can spread quickly online, it’s important to check for news using a reliable source. We’ll update this website if anything is announced.

If there is an energy shortage, you could be switched off for around three hours. If the shortage is likely to last a few days, an emergency power cut rota will be published on this website.

When you enter your postcode, you will be able to see when you will have a power cut the next day.

You’ll also see a timetable showing when there is a risk of a power cut for the days after that, even if this isn’t confirmed. It will be important to keep checking your power cut rota every evening.

Frequently asked questions


What is a Block Letter?

Your home and street are connected to the electricity network through a substation. This connection is given a code known as a ‘Block Letter’. The country is divided into many block letters. This helps the electricity networks to manage emergency power cuts fairly.

Your Block letter is static and will not change unless you move home. It is based on where you live and how your property is connected to the electricity grid. You can find out your Block Letter on your electricity bill under the address.

Everyone sharing the same Block Letter shares the same power cut timetable.

Where do I find my Block Letter?

You can find your Block Letter by:

  • Enter your postcode on our website.

  • Checking your electricity bill where your Block Letter is displayed in a square box on the top third of the front page.

  • If you cannot find your Block Letter from either this website or your electricity bill, dial 105 to speak your local network operator.

I am medically dependent on electricity. What should I do?

In most cases, customers who are medically dependent on electricity will be familiar with the process and limitations of their equipment as power cuts can occur from time-to-time during a typical year, including during severe weather, for regular maintenance or due to damage and other routine faults. These customers often have backup power sources to keep vital equipment powered for several hours during a power failure.

Customers who require a continuous supply of electricity for medical reasons and would need medical support during a power cut, should seek advice from their local health service provider.

Backup power supplies and associated equipment should be regularly checked and maintained by a competent person. If you’re concerned, you should speak to your medical equipment or health care provider now.

What should I do to prepare?

You can take some simple steps to prepare:

  • Keep a mobile phone fully charged.

  • Add the emergency numbers to your contacts.

  • Bookmark this website on your mobile phone.

  • Keep a torch handy in case you are without power during the night.

  • Have warm clothes and blankets accessible.

  • Check in on your neighbours, friends and family to make sure they’re okay.

  • Tune your car radio or a battery-operated radio to your local station to stay informed.

  • Only use alternative forms of heating, lighting or cooking if you can do so safely.

  • Make sure you have a carbon monoxide alarm which is tested and works.

  • Ensure you have some food and drink available that does not require electricity to heat or prepare it.

  • Keep fridge and freezer doors closed to preserve their contents.

  • You may wish to consider limiting the use of your laptop or your smart phone in the lead up to the emergency power cut to preserve the life of the battery.

What should I do during a power cut?

  • Switch off all electrical appliances at the wall except fridges and freezers.

  • Leave a light on so you know when power is restored.

  • Check to see if your neighbours or relatives are OK.

  • If the weather is cold, keep blankets and warm clothing near you.