U.S. Department of Labor
Process: Shipboard Electrical
Table of Contents
Ground-Fault Circuit Interrupters (GFCIs)
During ship repairing or shipbuilding operations, it is recommended that GFCIs are used with temporary systems or portable equipment. GFCIs detect any difference in current between the two circuit wires (the energized black wires and grounded white wires). This difference in current could happen when electrical equipment is not working correctly, causing leakage current. If leakage current ( a ground fault) is detected in a GFCI-protected circuit, the GFCI switches off the current in the circuit, protecting the worker from a dangerous shock. GFCIs are set at about 5 mA and are designed to protect workers from electrocution.
There are five types of GFCIs, however, in shipyards, only portable and cord-connected types are usually used. The portable types GFCIs are designed to be easily transported from one location to another. They usually contain one or more integral receptacle outlets protected by the GFCI module. Some models are designed to plug into existing non-GFCI-protected outlets, or in some cases they are connected with a cord and plug arrangement. The portable types also incorporate a no-voltage release device that will disconnect power to the outlets if any supply conductor is open. Units approved for outdoor use will be in enclosures suitable for the environment. If exposed to rain, they must be listed as rain resistant.
Cord-connected GFCIs have an attachment plug that incorporates a GFCI module. The plug provides protection for the cord and any equipment attached to the cord. The attachment plug has a non-standard appearance and is equipped with test and reset buttons. Like the portable type, cord-connected GFCIs incorporate a no-voltage release device that will disconnect power to the load if any supply conductor is open.
Test each GFCI before use to ensure that the ground-fault protection is still functioning. GFCIs have a built-in test circuit with test and reset buttons. The test circuit imposes an artificial ground fault on the load circuit.
Other important precautions for reducing workers' exposure to electrical hazards include: keeping equipment out of water, implementing a strong equipment maintenance program, instructing workers to keep their hands dry when plugging/unplugging equipment, and the proper grounding of equipment.