The transaction is expected to close in the first quarter of 2009, subject to regulatory approvals.
ABB currently owns a 21 per cent stake in the joint venture, and has agreed to take over the 79 per cent stake of the business owned by the Ensto Group.
Ensto Busch-Jaeger was formed by ABB subsidiary Busch-Jaeger Elektro of Germany and Finland’s Ensto Group to produce wiring accessories and installation material for residential and commercial building markets in the Nordic region.
In 2007, Ensto Busch-Jaeger had revenues of about $55m (£37m).
The business, which is based in Porvoo, Finland and employs around 120 staff, will become part of ABB’s Automation Products division.