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Ohio State University Extension


Grounding and GFCI Protection

Small Farm and Gardening Safety and Health Series
Agriculture and Natural Resources
S. Dee Jepsen, Associate Professor and State Safety Leader, Agricultural Safety and Health, Food, Agricultural and Biological Engineering
Jeffery Suchy, Graduate Student and Lecturer, Food, Agricultural and Biological Engineering

Electricity always follows one or more nonstop paths of least resistance. If the body becomes part of a path, electricity will pass through it. Dry hands and feet offer more resistance to electrical current than wet hands or feet. In either case, the current can be lethal, especially if the electricity passes through vital organs, such as the heart or lungs.

Grounding electricity means creating a direct path to earth that does not include the body or equipment. Proper grounding protects people from injury and damage caused by faulty wiring and circuit malfunction.


Missing Ground Prong Properly Grounded Cord Damaged Insulation
GFCI Breaker GFCI Receptacle Portable GFCI


Proper Grounding

Electrical power tools and cords used outside or in moist conditions should have a true ground. If tools do not have a ground prong, they should be double-insulated. For example, a drill has a third wire, which acts as the ground wire, incorporated in the design. This means, if a fault occurs, the current will follow the ground wire, not the operator. Usually a three-prong plug in a three-hole outlet provides a proper ground. Never cut off the third ground prong. Use an approved adaptor, if necessary.

If an electrical system has only two-prong receptacles, it is not properly grounded. In that case, use only a double-insulated electric power tool. 

Always check that portable electric hand tools are properly grounded. If a power tool develops a short, repair it before using it again.

Ground-Fault Circuit Interrupter

A ground-fault circuit interrupter (GFCI) is specifically designed to protect people from electrical shock. GFCIs quickly (1/40th of a second) shut off the power in the event of an electrical short or ground fault. GFCI protection can be obtained by using special breakers, hard-wired receptacles and portable models, which can be plugged into any electrical outlet. GFCI protection should always be used when operating electrical devices outside and in wet or damp locations. 


• NFPA 70EStandard for Electrical Safety in the Workplace. Quincy, MA: National Fire Protection Association, 2009.

Reviewer: Kent McGuire, CFAES Safety and Health Coordinator, Food, Agricultural and Biological Engineering
Originally posted Nov 19, 2015.