Utility Lineman Wearing Safety Gear


Dielectric Testing of Rubber Goods is Essential for Line Worker Safety

According to the U.S Bureau of Labor Statistics, the average annual fatality rate for power line workers is 20.9 deaths per 100,000 employees. Keeping workers safe in the field depends on a variety of personal protective equipment (PPE) items. One of the most important lines of defense for line workers is rubber goods.

The risk of injury, and even death, from electric shock is drastically reduced by taking a few simple steps with your rubber goods. Keep up with daily inspections and cleaning, use safe storage methods, and safety test your equipment regularly at an experienced, accredited testing lab.

Learn why rubber goods are so important to worker safety and how to ensure that your equipment is ready for any situation.

PPE for Electrical Safety

Rubber goods include gloves, sleeves, boots, blankets, line hoses, and more. These are key PPE in preventing electrical current from entering your body and causing injury or death. The Occupational Health and Safety Administration (OSHA) requires rubber goods to be worn when workers are within close proximity to electrical equipment.

OSHA upholds and enforces the way electrical work can be performed based on the standards issued by the ASTM F18 Committee. This committee is made up of experts in the electrical industry who set national standards and guidelines.

Why Test Rubber Goods?

Complying with ASTM standards, in addition to regular care and maintenance, reduces the risk of injury in the field. Better yet, it makes users and their companies OSHA-compliant. This keeps workers safe and reduces the risk of an OSHA fine.

In addition to daily inspection, proper storage, and care, rubber goods should be sent to a top-quality, NAIL for PET-accredited rubber testing facility. At these facilities, equipment is tested and recertificated to stay compliant with ASTM standards (ASTM 478, 7.1, F479, 8.1.1, and F496, 7.1).

ASTM F496, 7.1 states that rubber gloves should be electrically tested before their first use and every six months after. Sleeves, line hoses, blankets, and hoods have their own specific testing cycles. Cycle dates are determined by the end user, but maximum testing intervals are mandated by ASTM. All ASTM codes are available online for review.

"It costs a little more, but you would hate to have something happen in the field that could have been avoided.“

  • Supply Manager, Wisconsin
Rubber Goods Testing in Six Steps

Maintaining a safe work environment starts with having the right equipment and processes in place. Attention to detail and quality control should be a top priority when selecting rubber goods. Outsourcing rubber goods testing can provide convenience and ease of mind. High-quality testing of rubber goods consists of:

  • Cleaning
  • Visual inspection
  • Electrical testing
  • Certification
  • Date stamping
  • Packing & Shipping

Let's discuss each of these testing methods in more detail:


A NAIL for PET-accredited test lab handles cleaning the outside and inside of all rubber goods. The lab removes old stamps and cleans the items thoroughly. Goods then dry completely before going on to a visual test that is performed by a trained inspector (ASTM 1236). Properly cleaning rubber goods removes conductive and compromising dirt and oil, while allowing for the best visual inspection.

Visual Inspection

While rubber goods may look safe, inflation or rolling of rubber goods can reveal hidden damage. During the visual inspection of gloves and sleeves, the rubber is inflated, inspected, turned inside-out, inflated, and inspected once again. Blankets are carefully rolled and scanned on both sides. Line hoses are opened up and then rolled.

Inflation and rolling allow for a better scan of the rubber. It also exposes physical imperfections. If there are any scratches, punctures, or cracks in the rubber, the item doesn't pass visual inspection. Items that fail visual inspection don't move on to the next steps.

Electrical Testing

Electrical testing of rubber consists of exposing the rubber to an electrical voltage. The test voltage is based on the rubber's class (ASTM F496: Section 7). In a dielectric withstand test, voltage is applied beyond an item's maximum field use. This ensures the item can withstand the electrical stress it will be subjected to while in use.

If an electrical failure occurs, a hole will burn through the rubber. The item is then stamped as a failure because it is unfit for electrical use.

Certification, Date Stamping, Packing, and Shipping

After the rubber passes the visual and electrical testing, it is then certified with a date stamp. This stamp includes either the date of the test or the expiration date, the voltage the PPE was tested up to, and the name of the testing facility. A special ink is used for the stamping. It's safe for use on rubber and won't fade or wipe off during normal use.

Once the stamps have dried, gloves and sleeves are dusted with 100 percent talc powder to absorb any remaining moisture (ASTM F478, F479, and F496). Gloves and sleeves are then placed in new plastic bags and heat-sealed. Blankets and line hoses are placed securely in plastic containers or totes. Proper care is taken to ensure that the goods are not crushed or folded when packaged. It’s recommended that plastic totes be used for shipping to provide solid protection while in transit.

Are your rubber goods keeping your employees safe?

Regular testing of rubber goods makes it easy to answer this question. Testing does more than bring your facility into compliance. It keeps employees safe from dangerous, even deadly, situations. Take a few minutes to inspect the equipment so you can be properly protected from any electrical danger.

Chris Manos


Chris Manos
Chris Manos joined Wesco in 2014. He is currently the Senior Operations Manager for all Wesco dielectric testing facilities in the US, responsible for the efficient and accurate handling, testing, and distribution of di-electric rubber goods and grounding equipment across the country. Chris is also a Wesco’s voting representative on the ASTM F18 committee as well as the Vice President of the board of directors of NAIL, a position he has held since April 2022.

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