Gloves in Arc Flash: A Big Change in NFPA 70E
Some gloves can be more of a hazard than a help in an arc flash situation.
- By Hugh Hoagland, Don West
- Jan 01, 2012
Sam (the name has been changed) worked for an electric utility. He was working near energized equipment and wearing arc flash gear as he cleaned up oil from a transformer. Because the oil might contain PCBs, Sam was wearing nitrile gloves for their chemical resistance. The main hazard, in his mind, was the possible PCBs.
When the arc occurred, Sam broke no work rules. But because his hands were burned, the utility wanted to know whether it could have provided a more adequate glove for this task. The answer at the time was no.
Today, more multi-hazard gloves are available on the market, and multi-hazard protective products are becoming the norm. When NFPA 70E began requiring clothing/PPE for arc flash, most companies thought of flash suits and rubber gloves with leather protectors. As NFPA 70E has expanded, gloves have moved to the forefront.
Rubber and Leather
ASTM D120 for rubber insulating gloves and ASTM F696 for leather protectors were never considered for arc flash in the past. Industry basically focused on a long-accepted performance test on rubber gloves, during which the rubber gloves proved to work very well for shock protection. The good news is these gloves have shown resilience for arc flash, too.
The limit on this two-glove combination for arc flash (leather protector for arc flash over rubber for shock protection) is the ignition point for the rubber gloves, which has been commonly established by testing in the past few years. Some rubber gloves ignite only at very high levels. Low voltage gloves cause the most concern because they are the thinnest and are most likely to ignite -- some colors, as low as 17 cal/cm². But within the next few years, these gloves are likely to have arc ratings, just as many of the non-shock, arc flash gloves have ratings.
Currently, rubber insulating gloves are the only option for arc flash and shock. This is likely to remain the case in the near future -- although companies are considering research using materials other than rubber.
The real issue is not for the electrician. For the electrician performing energized electrical work, rubber insulating gloves are currently the only legal choice as a result of OSHA’s citation of the D120 standard for shock protection and the practicality of rubber’s electrical insulating properties. The primary challenge is to provide arc rated gloves for low voltage switching and disconnect operation because non-electrical personnel routinely perform both of these tasks, and they do not require shock protection. Non-electrical personnel often must protect themselves from other hazards, or they may have other needs. Rubber and leather may not provide the protection or performance they require.
Issues with Leather
Leather protectors are not an option for operations such as food preparation, pharmaceutical cleanrooms, paint cleanrooms, or computer chip and hard drive manufacturing cleanrooms, which are often incompatible with leather protectors. The NFPA 70E standard, however, requires leather for arc flash protection as a protector worn over rubber gloves, recognizing that rubber can ignite.
Companies that cannot use leather protectors face two challenges: the retest requirement for rubber gloves when worn without a protector and the need for arc flash protection when using rubber gloves alone. These are not insurmountable but must be considered.
Some companies have used the OSHA1910.137(b)(2)(vii)(A) and ASTM F496 Standard Specification for In-Service Care of Insulating Gloves and Sleeves, an exception that allows workers to use one class greater rubber gloves for operations requiring higher levels of dexterity than rubber gloves with leather protectors allow. The rubber gloves, however, must be dielectrically tested after each use (though "use" is not defined). This method is limited by the retesting requirements and a lack of knowledge of the arc flash level of rubber gloves. Using a cover glove other than leather might be an option but is currently not allowed, according to ASTM F496, OSHA, and NFPA 70E.
Rubber gloves have a low risk of arc flash ignition when workers use leather protectors. The risk, though, increases substantially when no protector is used. Our extensive testing confirms that black rubber gloves are harder to ignite than other colors, due to the colorant being carbon black (see Figure 2). But when leather protectors are worn, the risk is further reduced by the leather’s blocking energy to the rubber.
The electrician has acceptable options available that are recognized by the standards bodies. Lately, the issue is for non-electricians who perform electrical tasks regularly. What does a worker wear to operate a 600V breaker or a disconnect?
The NFPA 70E stock answer, until 2012, is a leather glove. Then, the requirement will get a bit fuzzy since the standard’s new version requires leather to have a minimum thickness of 0.7 mm. Only leather protectors are sold with a minimum thickness, and they are only to be worn over rubber gloves. Wearing a leather protector as a stand-alone glove precludes its use as a protector again (see ASTM F496).
What was the committee’s intent? To encourage workers to use arc rated gloves. At the time of the standard’s final vote, the ASTM F18 committee had another standard under ballot. This proposed standard, however, could not be cited, which is why the NFPA 70E 2012 standard required leather gloves to have a minimum thickness of 0.7 mm or be arc rated gloves (arc rated gloves are required for HRC 3 and 4, if not using D120/D696 combination gloves).
What Are Arc Rated Gloves?
Arc rated gloves are already on the market by two methods. Sewn gloves can be arc rated by the fabric test method ASTM F1959 to meet ASTM F1506 (this method does not work well for leather because it has substantial thermal shrinkage), and all gloves can be tested and arc rated by the proposed standard, which uses a modified ASTM F1959 panel to hold a glove onto a sensor for testing. This allows the glove to be evaluated as a stand-alone glove, which exposes the thermal shrinkage and the full glove design better than using the standard fabric panel. The ASTM F18 committee has accelerated the glove test method to be voted again in April 2012, and this test method will foster more research on multi-hazard gloves.
There are many advantages of arc rated gloves versus rubber insulating gloves with leather protectors for arc flash. If there is no shock hazard, an arc flash glove can be lighter weight; protect from cut, chemical, and even other hazards; and be comfortable and cost effective enough for the worker to wear it all day long.
Additionally, some of the new arc flash gloves can be laundered so that oil buildup, which can provide an additional source of flaming, can be removed and the glove safely reused. This is not normally practical for leather. Figure 3 is an International Social Security Association study of burn locations from electrical incidents in Germany (this is the only burn location study we have found for electrical work). It should be noted that most of the burns are on the hands. Common work gloves often will ignite in an arc flash, and not wearing gloves almost always ensures some burn from arc flash exposures.
The Issue of Multiple Hazards
If a shock hazard exists with an electrical task, the only option is to use a rubber insulated or voltage rated glove (VR). Arc rated gloves (AR) can be rated for multiple hazards such as chemical, cut resistance, and arc flash.
Why would you not want to wear an electrical glove? Cost and fitness for use are the primary reasons. Rubber insulating or VR gloves are great when used for the tasks for which they were designed. They are basically the only option for shock protection.
An AR glove chosen for multiple hazards can meet non-electrical workers’ needs. AR gloves offer other advantages, too. They are better fitted to the hands than a common electrical glove. They are also thinner and easier to use, which is key to encouraging workers to wear PPE all the time.
Traditional leather gloves will protect from arc flash, but they may not be the best glove for many applications.
This article originally appeared in the January 2012 issue of Occupational Health & Safety.