The power supply to 42,000 customers in Lancaster, Morecambe, Carnforth has been lost at 4.00pm this afternoon.
Power was restored to all customers this morning after floodwater breached flood defences at Lancaster's main substation just before 11.00pm on Saturday, cutting power to 55,000 properties.
Engineers are still onsite and are investigating the cause of the outage and will update customers as soon as possible.
Mark Williamson, operations director for Electricity North West, said: “Unfortunately power has been lost to customers in Lancaster and surrounding areas.
“We are onsite and investigating the cause and we will update customers as soon as we find out more and again we would like to thank our customers for their patience and support during what continues to be an enormously challenging time for everyone involved.”
2,657 properties remain without power in Cumbria, where floodwater is restricting access for Electricity North West teams.
Flood defences at Kendal and Carlisle substations have held, protecting supplies to 110,000 homes.
Vulnerable customers, including some older or disabled people, or those with a medical dependency on electricity, can also sign up to the Priority Services Register by visiting www.enwl.co.uk/priority or contacting Electricity North West on 0800 195 4141.
• For updates please visit @ElectricityNW, visit www.enwl.co.uk or call 0800 195 4141