Inspection Detail

Inspection: 103390779 - Boston Edison Company

Inspection Information - Office: Boston South Area Office

Investigation Summary

FOUR CABLE SPLICERS AND TWO HELPERS WORKING FOR AN ELECTRIC UTILITY WERE RECONNECTING 36 CABLES TO THE SECONDARY OF A TRANSFORMER WITHIN A CONCRETE VAULT. THE CABLE HAD BEEN DISCONNECTED SO THAT AN ELECTRICIAN FOR AN INDUSTRIAL PLANT COULD REPLACE ELECTRIC EQUIPMENT. THE ELECTRICIAN COMPLETED HIS WORK, AND THE CABLE HAD TO BE RECONNECTED. THE TRANSFORMER ITSELF WAS NOT DEENERGIZED BECAUSE IT CONTINUED TO SUPPLY ANOTHER CUSTOMER. THE WEATHER WAS VERY HOT WITH TEMPERATURES IN THE 90S THROUGH THE DAY, AND THE TRANSFORMER CONTRIBUTED TO THE HEAT IN THE VAULT. FOR OVER 20 HOURS THE SPLICERS WORKED IN PAIRS, WITH AN EMPLOYEE OF ONE PAIR ON EACH SIDE OF THE TRANSFORMER WHILE THE OTHER PAIR OF WORKERS TOOK A BREAK FROM THE HEAT. THE CONDUCTORS BEING HANDLED BY THE SPLICERS WERE ENERGIZED AT 120 VOLTS TO GROUND, AND ONLY ONE CONDUCTOR WAS HANDLED AT A TIME. THE CONNECTION POINTS ON THE TRANSFORMER WERE ALSO ENERGIZED AT 120 VOLTS TO GROUND, WITH THREADED FITTINGS WHICH PROTRUDED FROM A RUBBER MOLD ON THE CONNECTION TREE (POST) FOR EACH PHASE. THE SPLICERS WERE HANDLING THE LIVE INSULATED ENDS OF THE CONDUCTORS WHILE WEARING ONLY LEATHER WORK GLOVES ON THEIR HANDS. THROUGHOUT THE DAY THE MEN CHANGED SHIRTS AND GLOVES AS THEY BECAME DAMP FROM SWEAT. ONE EMPLOYEE WAS HOLDING THE END OF ONE PHASE CONDUCTOR WITH HIS LEFT GLOVED HAND AS HE GRASPED THE PROTRUDING CONNECTOR ATTACHED TO THE SECONDARY POST FOR THAT PHASE OF THE TRANSFORMER WITH HIS RIGHT GLOVED HAND. THE EMPLOYEES HAD USED A VOLTAGE TESTER AND DETERMINED THAT THIS WAS THE CORRECT SECONDARY POST FOR THIS CONDUCTOR. THE EMPLOYEE WAS STANDING ON A WOODEN PLANK AND WAS NEXT TO, AND EVIDENTLY IN CONTACT WITH THE GROUNDED TRANSFORMER CASE. THE EMPLOYEE BEGAN TO SHAKE AND THEN COLLAPSED. CPR WAS ADMINISTERED BUT TO NO AVAIL. HE HAD BEEN ELECTROCUTED THROUGH HIS LEATHER GLOVES.

Keywords: ELEC PROTECT EQUIP, ELECTRICAL, ELECTROCUTED, E PTD, TRANSFORMER VAULT, ELEC UTILITY WORK, TRANSFORMER