Recent updates to OSHA 1910.269(n) and 1926.962 have emphasized the responsibility of the employer to ensure their personal protective grounding equipment and practices are adequate to protect employees from hazardous differences in electrical potential. One important aspect that is often overlooked is the care and maintenance of the grounding equipment.
Personal protective ground sets are often dropped in the dirt and thrown in the back of trucks. Minor damage, oxidation, and other contamination on the contact surfaces or in the connections can significantly impact the effectiveness of the grounding equipment in case of a fault current. For this reason, it is essential to care for and maintain the equipment.
The first part of proper care and maintenance for personal protective grounding equipment is to inspect and clean before each use. This includes inspecting for: damage to any components, missing components, loose connections, and oxidation or other contamination. The cable should be inspected for damage to the jacket such as splits/cuts/abrasions, melting, or other degradation, kinks or other deformation, oxidation, contamination, or breakage in the cable strands. If the grounding equipment has experienced a fault current, it should be permanently removed from service. Personal protective grounding equipment with damaged or missing components should also be removed from service for repair or replacement. Loose connections should be tightened to the manufacturer’s recommended torque values.
The contact surfaces of the clamps should be cleaned with a wire brush prior to installation on the line, and also the contact surface of the conductor, bus, etc. where the clamps will be installed. Visible oxidation or contamination in other connection points, such as where the ferrule connects to the clamp, should be cleaned and may require periodic disassembly for thorough cleaning with a wire brush. To minimize risk of damaging the grounding equipment, care should be taken during handling and storage. Protective bags can help keep the ground sets clean and dry when not in use.
Another important part of proper care and maintenance is periodic electrical testing. ASTM F2249 and other industry standards do not specify an interval for testing; however, the generally recommended guideline is at least once per year. The employer should consider frequency of use, work conditions, condition of the equipment, care of the equipment, etc., to determine if more frequent testing should be performed.
ASTM F2249 provides details on test methods and pass/fail resistance values for personal protective ground sets. The CHANCE® ground set tester is one option for testing that provides several advantages including its use of a 5-volt DC source and its diagnostic probes used to identify the problem component/connection. The 5 volts cut through the thin layer of high resistance oxidation. The oxidation can cause false negatives when testing with lower voltages. The DC source provides a distinct advantage over an AC source as inductance is not an issue. Unlike with an AC source, the cable does not have to be laid out in any pattern, can be coiled and can be in contact with metal surfaces or concrete containing rebar.
If properly cared for and maintained, personal protective grounding equipment can offer protection for many years. Of course, if loads on the circuit increase, you may need to upgrade your grounding equipment sooner. A periodic review of fault current levels is recommended.