The £7m turnover firm is a specialist contractor to the water and waste-water industry’s and will strengthen Eric Wright Group’s civil engineering division.
It employs around 88 staff out of offices in Radcliffe, Worcester and Dumfries and provides works for an array of contractors including Costain, Barhale and Galliford Try.
Site Electrical built up a strong track record in project design, installation, maintenance and management of projects for Severn Trent, Welsh Water and United Utilities in recent years.
Tom Murphy, who established Site Electrical 29 years ago, plans to stay on as a consultant.
Mr Murphy said of the deal: “Following an initial approach and after much consideration, I decided that it would be positive move for Site Electrical to become an independent part of Eric Wright.
“It will enable us to accelerate our planned growth and expansion of our business that is already underway.”