Inspection Detail

Inspection: 305222762 - Nature Coast Electric, Inc.

Inspection Information - Office: Tampa Area Office

Investigation Summary

On February 21, 2002, Employee #1, a worker with Nature Coast Electric, Inc, an electrical contracting firm, was in the process of crawling under a mobile home to troubleshoot an inoperative sump pump at a private residence in Ozello, FL. The employee contacted the frame of the mobile home as he was entering the space and was electrocuted. The mobile home is supported by concrete blocks with wood shims between the blocks and the metal frame. Withlacoochee River Electric Cooperative (WREC) supplied 120/240-volt service via overhead transformer and service conductor to a wood meter pole. A breaker panel was located on this pole below the service meter. The neutral, meter enclosure, and service enclosure were grounded to earth at this location with a ).625 in. diameter galvanized rod. The pole mounted service enclosure feeds a service panel located in the mobile home and several branch circuits. One of the branch circuits would feed a 120-volt duplex receptacle located underneath the mobile home and attached to its metal frame. This outlet was used to supply power to a PVC-enclosed lift station located under the mobile home. Upon testing the lift station wiring, an electrical short was found between a source conductor and the ground conductor that feeds the lift pump. After energizing the service, a voltage in excess of 100 volts was measured between the mobile home frame and the service ground when the lift station was plugged into the outlet. Several problems were found that would prevent the circuit breaker from tripping. These were (1) the ground conductor between the outlet and the service panel was broken, (2) the ground conductor between mobile home frame and the service ground was broken, and (3) the breaker supplying this outlet was rated at 30 amps. The combination of the above mentioned problems prevented the fault needed to trip the breaker. When the source conductor in the lift pump shorted to the ground conductor, there was no closed circuit that would allow fault current. Since the outlet ground is tied to the frame and the frame was electrically "floating", the frame became energized. There appeared to be some leakage fault current, but not enough to trip a 30-amp breaker. The hazard could not have been reasonably foreseen by the employer.

Keywords: ELECTRICAL, INADEQUATE MAINT, UNSECURED, ELECTROCUTED, EQUIPMENT FAILURE, CIRCUIT BREAKER, EQUIPMENT GROUNDING, ELECTRIC SHOCK, ELECTRICAL FAULT