Flood defences that were upgraded in 2010 to withstand a '1-in-100-years' flood were breached just before 23:00 on Saturday night. Engineers from the power company are working with Lancashire Fire and Rescue Service to determine when it is safe to access the flooded substation.

Only after gaining safe access to the substation can engineers assess the damage and begin repairs. Restoration of supplies could take a number of days for the majority of customers, depending on the level of damage.

Generators are currently being delivered to key sites that are determined to be most in need, including a respite centre which has been set up at Salt Ayre Leisure Centre in Lancaster.

Another 4,000 properties are without power across Cumbria.

Mark Williamson, operations director for Electricity North West, said: "This is an incredibly challenging time for many people and I can assure them that we are working with the emergency services to coordinate the best response we can.

"Our engineers have been out since Saturday morning repairing faults on the network and we envisage that most faults caused by wind will be restored later today as we continue to work around the clock. Unfortunately, power cuts caused by flooded substations will take significantly longer to restore.

"Please listen to local radio for emergency information or follow official updates on social media for the latest information."

Electricity North West invested £500k on improved flood defences at the Lancaster substation in 2010 to withstand a '1-in-100-year' flood.

Electricity North West engineers have restored power to more than 13,000 properties throughout the day.

Follow @ElectricityNW on Twitter or visit www.electricitynorthwest.co.uk for updates. To get the latest flood advice and information in your area please go to the Environment Agency.

For more information about flood alerts click here and to keep up-to-date with the weather in your area visit the Met Office.

What to do in a power cut:

• Use a car radio to listen to the radio for updates
• Use a battery operated or wind-up torch
• Have warm clothes and blankets available
• Check on your elderly or sick neighbours and relatives
• Make sure electrical appliances, such as cookers, electric fires etc are turned off
• Join our Priority Service Register if you need extra support electricitynorthwest.co.uk/priority
• Keep your freezer and fridge door closed to prevent defrosting​
• If you need any advice ring us 24/7 on 0800 195 4141 or follow @ElectricityNW

During a flood:

• If water is about to enter your property, turn off your electricity supply, but only if safe to do so
• Do not touch any electrical equipment or cables whilst you are standing in flood water
• Do not touch any electrical equipment or cables that have been immersed in flood water