Silverstream Switchboards director Ben Baxter said the company, which trades as Bremca Otago, was building new premises in Dukes Rd as it had continued to grow.
''We've grown from a three-person business up to a 10-person business and we are expanding,'' Mr Baxter said.
The company would move from the rented Factory Rd premises it had been since starting 14 years ago, he said.
The new building would be twice as big as its rented building and would have a 740sq m workshop and a 230sq m office for its 10 staff.
''In time, we are hoping to take on more staff.''
The dairy sector was buying many of the company's industrial and commercial switchboards, he said.
It sold switchboards to many Otago businesses, like supermarkets and freezing works.
The national company had seven branches.
The Mosgiel service area included Dunedin, Wanaka, Queenstown, Balclutha and Oamaru.
Mr Baxter expected work from the Christchurch rebuild and from earthquake strengthening of many Otago buildings.
The Dukes Rd building was expected to be finished by September.
