The manufacturer of a large wind turbine which toppled during gales in Devon has blamed "grout" and "the manner in which the tower was fixed" for the collapse.
The findings are the first to emerge from a series of investigations launched after the fall of the 111ft (34m) turbine, which was followed by a second collapse in Cornwall.
Canadian firm Endurance Wind Power, makers of the E3120 turbine, which was found crumpled on farmland in Bradworthy last month, has also dismissed speculation that sabotage may have contributed to the fall.
But the investigation into its UK "fleet" has identified a further 29 turbines that might have been affected by the same problem as the East Ash Farm equipment, some of them thought to be in Somerset, Devon and Cornwall.
In a statement, the company said: "While there was no malfunction or abnormality with the turbine or tower (contrary to early inaccurate media reports of a fire and and/or missing fasteners), there was a problem with the structural grout and the manner in which the tower was fixed to the foundation that affected the durability of the anchor rods resulting in the tower collapse.
"The customer in this case has been assured that his turbine will be replaced and the foundation will be corrected."
Parallel investigations by the Health and Safety Executive and installers Dulas Ltd are continuing into how the turbine crashed down less than three years after it was commissioned.
In a separate incident, Glasgow-based Gaia Wind has written to more than a dozen owners after its 60ft (18m) tower was toppled at Winsdon Farm, North Petherwin – the family farm of Liberal Democrat Cornwall Councillor Adam Paynter.
Experts said installation companies routinely contract out ground works to civil engineering firms.
Bob Barfoot, North Devon chairman of the Campaign to Protect Rural England and a consultant on dozens of wind power schemes, said the overall safety record of UK turbines was good but predicted that the current proliferation of plants meant a serious accident was inevitable at some point.
"We could see from photographs that the anchor rods had somehow failed and broken off," he added.
"This is a large piece of equipment that operates with large rotating blades without any form of guard – if something goes wrong the blades can fly off and travel a considerable distance."
A spokesman for Dulas said the company did not wish to respond directly to the claims by Endurance or discuss any other contractors involved in the construction.
In a statement the firm, which is based in Wales, added: "Dulas is committed to working with its partners to ensure that the affected customers can resume the production of electricity as soon as possible.
"Our investigations into the cause of the incident are ongoing."
