Rubber insulating gloves are class-rated by the maximum voltage they're built to handle: Class 00 tops out at 500V AC, Class 0 at 1,000V, Class 1 at 7,500V, Class 2 at 17,000V, Class 3 at 26,500V, and Class 4 at 36,000V. Picking the right class for the job matters, but a correctly rated glove with a pinhole in it protects nobody.
The air inflation test
Before every single use, the glove gets rolled from the cuff toward the fingers to trap air inside, then checked for anything that shouldn't be there - pinholes, cuts, embedded debris, or the fine surface cracking that signals ozone damage. A glove that won't hold air, or that shows any physical damage, gets rejected on the spot. It takes about 15 seconds. It's not a box-checking formality; it's the last line of defense between a hand and a fatal current path, and it's genuinely quick enough that skipping it isn't about time pressure - it's about habit.
The six-month retest most people don't think about
Visual inspection catches physical damage, but it can't catch degraded dielectric strength. That's why rubber gloves also require a formal electrical retest every six months - high voltage applied across the glove wall to verify the insulation actually holds. Gloves that fail get destroyed, not patched. The retest date is stamped on the glove itself, and a glove past that date is treated as non-conforming regardless of how clean it looks. A glove can pass a visual check and still be well past its dielectric retest - which is why both checks exist, and neither substitutes for the other.
Storage and the leather protector rule
Gloves live in their canvas bag - not plastic - kept clean, dry, and away from heat, ozone, and petroleum-based products, all of which degrade rubber over time. Leather protectors go over the rubber gloves during most electrical work, but they protect the rubber from physical damage only; they carry no electrical rating of their own. A leather protector without the rubber glove underneath it is not PPE.
Full PPE inspection procedures for arc-rated clothing, hard hats, insulated tools, and grounding equipment - not just gloves - are covered in the Study Guide, with practice questions in the Exam Companion.
Standard reference: ASTM D120 (testing) / ASTM F496 (inspection).