The Electrical Trades Union has lashed out over safety concerns for thousands of apprentice electricians, after one of Australia's largest training providers, Careers Australia, admitted it had engaged in "unconscionable conduct" in recruiting under-qualified students in some of the nation's poorest areas.

On Monday, the Australian Competition and Consumer Commission won a court-enforced order that compelled Careers Australia to repay $44 million in debt for students who had been signed up to courses they believed were free or who had been lured through inducements such as iPads.

The order has threatened the expansion plans of Careers Australia, with controversy surrounding its recruitment practices in the scandal-plagued private college sector hampering its efforts in its separate apprenticeships arm.

Master Electricians, the largest trainer of electricians in the country, signed a contract with Careers Australia in October to deliver training to thousands of the nation's future electricians.