The order comes as a result of an accident in which a Hydro One worker fell 30 metres to his death in Cumberland on May 30.
"Our investigation into the fatality in Ottawa included a re-enactment of that incident, which showed us shepherd's hooks may become disengaged from their attachment point, unintentionally," Mr. Skeaff said.
Criminal charges will not be laid, Ottawa police said.
A shepherd's hook is a long staff, with a hooked end, that is attached to a lifeline that is then attached to a harness around a worker's waist. The hook is slung over a horizontal structure, in this case a steel girder, to prevent the person from falling.
"We've decided that they don't provide the amount of protection that is required by law under the Occupational Health and Safety Act," said Mr. Skeaff.
Ottawa paramedics said the 55-year-old man was assembling a hydro tower on the north side of Wilhaven Drive, between O'Toole and Quigley Hill roads, when he fell.
Three of his co-workers witnessed the fall and performed CPR on the injured man, who was pronounced dead at the scene. It is believed that he suffered massive head injuries. The man's name has not been released.