What causes a power cut?

The most common cause of power cuts is damage to cables and other infrastructure. Find out more about the different types of power cut.

If there’s a power cut, report it online.

Planned power cuts

This is when maintenance work is carried out to improve the power network. A lot of work can be carried out without switching the power off, but sometimes it is necessary to turn off the power for a short time.

What you can expect

If your electricity network operator needs to switch off your power for planned maintenance, they will give you as much notice as possible. They aim to give you at least 48 hours’ notice. If the work has to take place because of an emergency, it might not be possible to let you know in advance.

Unplanned power cuts

Unplanned power cuts happen when there’s a problem on the power network. Like the trip switch in your home, the electricity network has safety equipment which switches power off if it detects a problem. This can happen if someone or something has damaged a wire, cable or other piece of electrical equipment.

What you can expect

If you have a power cut, you should report it online. Your local network operator will look into the problem and keep you updated while they work to reconnect you.

Depending on the cause of the problem, they might need to send a team of engineers to look at equipment or a substation near your home. They will rarely need to come into your home but if they do, they will always show identification. If someone calls at your door, always check their identification badge. You can call 105 for free to confirm they are who they say they are. Genuine power company employees won’t mind waiting outside while you do this.

If you are a member of the Priority Services Register and it’s likely the power will be off for a while, your network operator will try and contact you to keep you updated.

Power cuts because of an energy shortage

When there’s a shortage of energy, it might be necessary to switch off your power for a short time. This is extremely rare, but if it is needed, these power cuts will help ensure there’s enough energy for everyone, especially when energy is in high demand like during teatime.

Find out more on our ‘Energy shortages’ page.

Energy shortages

The National Energy System Operator (NESO) 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, NESO 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.