UK Power Networks has started work on a £1.2 million project to upgrade Brighton's electricity supplies.
The firm has started a five-month project to further increase the reliability of electricity supplies for 21,000 homes and businesses.
Two major pieces of equipment are being replaced at the local electricity substation. The equipment, known as transformers, play a key role in keeping the lights on.
Gary O'Brien, project manager at UK Power Networks, said: "We are investing in new equipment at the substation to make sure electricity supplies in the city remain reliable into the future.
"Investments like this are taking place throughout the South East this year to maintain high levels of network reliability and a good service for local homes and businesses.
"This equipment has served Brighton well over many years but it is now time for renewal so we are delighted to be carrying out these improvements, which will serve the city for many years to come."
Most of the work will take place behind the scenes, inside the electricity substation. One of the most noticeable aspects of the project will be when the new 44-tonne transformers are delivered to the substation in the heart of the city, in July and October, then craned into position.
Electricity enters the electricity substation at 33,000-volts and is stepped down by the transformers to 11,000-volts to be delivered to local substations which serve individual homes.