Balfour Beatty Utility Solutions (BBUS) has agreed a three-year £28.5m contract with Western Power Distribution, for electrical infrastructure work in south Wales.
There is also the option of a three-year extension.
The contract, which begins in November, covers planned and emergency works, including excavation, cable laying and reinstatement work for low and high voltage networks
Tony Scott, director of electricity at BBUS, said: "This contract award offers a great opportunity to build on our proven track record and experience in this sector. We have an extensive history in the electricity industry, having worked with all of the UK distribution network operators and transmission network owners on design and delivery of work."
BBUS has worked with Western Power Distribution for 10 years.