Police arrested seven men and recovered half a ton of stolen copper cable in a joint operation in Woodstock last week.
The men, all in their 20s, were arrested on railway land, according to Sergeant Hilton Malila, of Woodstock police.
Large quantities of copper cable, including railway signalling cables, were seized in the bust.
Metrorail spokeswoman Riana Scott said the arrests had been made after Metrorail security staff and the Rail Enforcement Unit searched an empty building notorious as a den for stolen goods.
“Woodstock police were called to assist the team. While searching one of these buildings, the officers came across 500kg of stolen copper cable belonging to the Passenger Rail Agency of South Africa, as well as to the City of Cape Town,” said Ms Scott.