Insulated gloves are one of the most important pieces of safety equipment for substation workers. If they aren’t effective… well, I’m sure you can imagine. Insulating gloves must meet certain standards and be stored in a way that doesn’t compromise their insulating qualities.
All gloves used for electrical work should meet, or exceed, the standards set by the ASTM International standard specification for insulating gloves, and they should also be electrically tested following the ASTM D120-14a and International Electrotechnical Commission IEC 60903:2014 standard.
Electrical safety gloves are categorized by the level of voltage protection they provide, and whether or not they are resistant to ozone. Rubber is susceptible to ozone, so if gloves are going to be used in an environment where the levels of ozone are high due to pollution, you must choose gloves that are ozone resistant. Type I gloves are not, but Type II are.
OSHA (the Occupational Safety and Health Administration) requires you to maintain your safety equipment, and this means that gloves must be inspected for damage before each day’s use, and after any incident that may have caused damage. OSHA standards also require an air test with each inspection.
Air testing is likely what you expect; the glove is filled with air and checked for leakage by listening and feeling for escaping air. Gloves shouldn’t expand more than 1.5x their size for Type I, and 1.25x their size for Type II during these tests. The test should be repeated with the glove inside-out.
Before every use, gloves should be checked for holes, rips and tears, and any other visual damage, including chemical exposure which often shows up as swelling or bubbling in the contaminated area.
In addition to daily inspection, OSHA requires periodic tests. Rubber insulating gloves must be tested before the first issue and every six months thereafter. Any gloves that have been purchased and stored cannot be issued unless they were electrically tested in the past year.
If a glove sustains minor damage between the wrist and the reinforced edge of the opening, you may repair the glove with a suitable patch or liquid compound, though the repaired area must have the same electrical and physical properties as the rest of the glove. If the glove sustains damage elsewhere, they must be thrown out.
Gloves must be stored properly when not in use – this means that they must be stored in a cool room that doesn’t get excessively hot, too much sunlight, too humid, ozone or subject to any chemical that could damage the rubber, and cannot be stored in a way that can damage the rubber (e.g. folding).
If in doubt, always retest before use.