The company was required to become PCI compliant in line with new industry regulations and was looking for a technology partner to help its business fulfil these obligations.
EDF Energy is one of the UK's largest energy companies, producing around one-fifth of the UK's electricity from its nuclear, coal and gas power stations.
It runs eight nuclear power stations in the UK and plans to build four new ones. Following the integration with British Energy in 2009, the company employs around 20,000 people at locations across the UK.
The Outpost24 system has been deployed across all UK sites and will ultimately extend to EDF's British Energy business, said the firm.
Jeffrey Irving, IT perimeter security manager at EDF Energy, said, "Even during the evaluation process we found immediate value in the Outpost24 solution, as we discovered vulnerabilities other systems on trial hadn't detected or they had inundated us with false positives."
Outpost24 carried out the installation and has continued to provide ongoing support with additional professional services.
Companies can dramatically cut their risks of data breaches by complying with payment standards, according to a recent from Verizon Business.
The report found that many businesses that had experienced intrusions were not compliant. Breached organisations were 50 percent less likely to have followed the PCI payment industry standard, it said.