Working with high voltage power systems carries many hazards and inherent risks. According to the U.S. Bureau of Labor Statistics (BLS), the electrical fatality rate in the mining industry is approximately 8 to 12 times higher than the rate of other U.S. industries.
While there are several personal protective equipment (PPE) items that should be utilized to keep workers safe in the field, one of the most important lines of defense is rubber goods.
Why rubber goods?
Rubber goods can include gloves, sleeves, boots, blankets, line hoses and other PPE that prevents an electrical current from entering the body, causing injury or death. The risk of injury or even death from electric shock is drastically reduced by taking a few simple steps with your rubber goods, including:
- Daily inspections and cleaning
- Using safe storage methods
- Regular safety testing for equipment through an experienced, accredited testing lab
Getting Up to Code
As an important part of worker safety, it is vital to make ensure that your equipment is ready for any situation. The Mine Safety and Health Administration (MSHA) has several requirements regarding the use and testing of rubber insulating goods. For example, 30CFR Part 77.606 requires the use of rubber gloves when handling any medium (661 to 1000 volts AC) or high (1001 and up volts AC) voltage trailing cable. 30CFR part 77.606-1 outlines the minimum requirements regarding those gloves.
Complying with ASTM and MSHA rules and reduces the risk of injury in the field and helps lower the risk of operational shutdown and/or fines. All ASTM codes are available online for review.
In addition to daily inspection, proper storage and care, rubber goods should be sent to a top-quality, NAIL for PET (North American Independent Laboratories for Protective Equipment Testing) and MSHA-accredited rubber testing facility. At these facilities, equipment is tested and certified in compliance with ASTM and MSHA standards (ASTM 478-09, 7.1, F479-06, 8.1.1, and F496-08, 7.1).
Code 77.704-8 (Protective equipment; testing and storage) requires that all rubber protective equipment used on work on energized high-voltage surface lines shall be electrically tested by the operator in accordance with ASTM standards, Part 28, published February 1968, and such testing shall be conducted in accordance with the following schedule:
- Rubber gloves, once each month
- Rubber sleeves, once every 3 months
- Rubber blankets, once every 6 months
- Insulator hoods and line hose, once a year
- Other electric protective equipment, once a year
Rubber Goods Testing in Five Steps
Maintaining a safe work environment starts with having the right equipment and processes in place. Prioritizing attention to detail and quality control regarding rubber goods is one such process. For both convenience and peace of mind, rubber goods testing can be outsourced. High-quality testing of rubber goods consists of:
Properly cleaning rubber goods removes conductive and compromising dirt and oil, while allowing for the best visual inspection. A NAIL for PET and MSHA-accredited test lab cleans the outside and inside of all rubber goods, removing old stamps and dirt. Goods are then dried completely before going on to a visual test performed by a trained inspector (ASTM 1236-96).
- Visual Inspection
30CFR part 77.704-7 states: “Each person shall visually inspect protective equipment and clothing provided him in connection with work on high-voltage surface lines before using such equipment and clothing, and any equipment or clothing containing any defect or damage shall be discarded and replaced with proper protective equipment or clothing prior to the performance of any electrical work on such lines.”
During 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.
While rubber goods may look safe, inflation or rolling of rubber goods can reveal hidden damage. Inflation and rolling allows for a better scan of the rubber and exposes physical imperfections. If there are scratches, punctures, or cracking in the rubber, it will not pass visual inspection or move on to the next step.
- Electrical Testing
Electrical testing of rubber consists of exposing the rubber to an electrical voltage. The amount of voltage is based on the rubber’s class (ASTM F496: Section 7). Rubber is electrically tested beyond its maximum field use to make sure that it 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 and Date Stamping
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. Special rubber-safe ink is used to make sure the date stamp won’t fade or rub off with normal use.
- Packing and Shipping
Once the stamps have dried, gloves and sleeves are dusted with 100% 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 hose 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 rubber goods keeping your team 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. A few minutes each day dedicated to proper equipment inspection is all it takes to protect against electrical danger.