UK Power will be integrated into McAlpine's infrastructure services division, which focuses on utility and highway renewal and maintenance services.
Ian Grice, chief executive of McAlpine, said: "We have worked with UK Power for some time and we know that it is a successful, well managed company providing high quality overhead line services."
He added: "This is a burgeoning marketplace and this acquisition will extend our coverage in the UK and Ireland."
In the year to March 2003, UK Power had sales of £5.8m and made an operating profit of £0.8m.
We have worked with UK Power and we know it is a successful, well managed company
Ian Grice, chief executive, Alfred McAlpine