Electrocution is a leading cause of death among construction worker fatalities, accounting for 8.5% of total fatalities in 2018.

The primary cause of death (over 50% of these fatalities) was from contact with live electrical equipment and wiring. Even though overhead electrical work has long held consistent standards, safety protocols for ground crews on de-energized sites are often more ad hoc and improvisational, which increases risks for workers.

Ground crews may suffer injury or even death from step and touch potential. Step potential is when an individual steps on a surface with high voltage and the current carries from one foot through the rest of the body. Touch potential is when an individual touches a surface with high voltage and the current carries through an individual’s body and into the ground. It takes 50 volts to break the electrical resistance of skin and cause injury. Serious injuries, or even death, may occur from exposure levels of no more than 50 milliamps.

The Institute of Electrical and Electronics Engineers (IEEE) recommends the accepted practice of developing an equipotential zone (EPZ), which bonds together all accessible conductors, structures, components and equipment through at least one low-resistance path. This bonding practice limits voltage exposure to the workers on a de-energized construction site. Grounding protection works to discharge voltage from nearby energized objects, reducing voltage to below a level that might cause injury to a worker.

While grounding causes the immediate operation of a circuit protective device to protect the equipment, a grounded circuit still has an active current which can contain voltage. To protect personnel on the ground from this voltage potential, it is essential to implement bonding.

The dangers of makeshift solutions

Many contractors believe that dropping chain-link fencing, wiring or other makeshift solutions are good enough when it comes to protecting their employees. What they fail to consider, however, is the risks that these thrown-together systems present. Because they are not made to be walked on or rolled over with machinery, they can deform or break apart under stress. This creates trip-and-fall hazards in addition to dangerous gaps in what little protection they provide against high voltage.

Using timber or composite mats is another common strategy that does more harm than good. This is because these can bend, crack and decompose over time. They won’t protect your workforce from electrical discharges, step and touch potential or other hazards the same way a quality EPZ grounding system could.

What is an EPZ grounding mat?

Also known as an EPZ grounding grate, an EPZ grounding mat is a one-piece galvanized steel grate used to create an equipotential bonded and grounded work zone. This zone then protects crews from step potential and Grade 5 fault currents. EPZ grounding mats are positioned on the ground then bonded together with 4/0 copper cables and 2-hole lug connectors, creating an equipotential zone for puller/tensioner sites and portable substations. The additional lug areas on EPZ grounding mats are for securing grounding cables between stringing equipment and grates. Our mats are quick to install and bolt together, allowing for quick assembly and easy removal.

Choosing high-quality EPZ grounding mats

Instead of creating makeshift EPZ systems, choose EPZ grounding mats to protect your ground workers. When doing so, consider these factors:

Durability and reusability

Are the mats reusable without depreciation to the quality of the structure? Using galvanized steel is a good option for ensuring high-quality materials that won’t break down over time.

Adherence to standards

Do the mats meet the ASTM F855-2015, IEEE 80-2013 or IEC 62271-102 Standards? Choose EPZ grounding mats that have been tested in real-world scenarios to ensure that they will adequately reduce voltage from step or touch potential below any hazardous levels.

Performance-tested

Have the EPZ grounding mats passed the following tests?

• Electrical short circuit capacity test
• Grade 5 fault current test
• Electromagnetic induction current test

Consistent product quality

Does the provider manufacture a consistent product that you can rely on? Pay attention to brand reviews and reputation to ensure that you have access to a consistent, high-quality product.

Best-in-class worker safety

Choose high-quality, performance-tested EPZ grounding mats for your grounding and bonding on de-energized worksites. It is possible to provide the same safety protections to your on-the-ground workers as you would to overhead utility workers. This will deliver a best-in-class protective environment that exceeds OSHA standards.

A better solution from United Rentals

Made from all-in-one galvanized steel grates, EPZ grounding mats offer superior protection in these high-voltage situations. They are built to withstand heavy loads and extensive use. Combined with how easy they are to install and dismantle, these can be a viable solution for your jobsite needs.

Contact United Rentals to learn more about our EPZ grounding mats for rent.