The militant Electrical Trades Union has won a court battle to gain access to workers on the site of the country’s largest transmission project in a ruling industry figures warn sets a precedent that could add to costs and delays for major renewables developments.

The Federal Court held that Spanish contractor Elecnor breached right of entry laws when it repeatedly refused the ETU access to workers on its $3.8 billion EnergyConnect project in south-west NSW for “specious, if not disingenuous” reasons.