PIT LABORER WAS MANUALLY MOVING SHOVEL ELECTRICAL POWER CABLE. A SECTION WAS FROZEN IN SNOW/ICE. HE ATTEMPTED TO PULL IT LOOSE AND FELT SOMETHING GIVE IN HIS LEFT SHOULDER. THE PAIN INCREASED OVERNIGHT AND HE REPORTED THE INCIDENT. HE WAS SUBSEQUENTLY DIAGNOSED WITH A CHEST STRAIN. THIS INCIDENT OCCURRED AT A GROUP II SWITCHHOUSE IN THE MINE PIT.