NCCR Electrical Practice Test

The key idea here is that insulative rubber PPE has a limited safe life. The material that provides the dielectric protection can degrade over time from aging, heat, flexing, ozone, and storage conditions. Because of that, the labeling on rubber insulating gear not only shows the voltage it can safely withstand, but also includes an expiration date. That date tells you the equipment should be retired or re-tested by that point, even if it looks fine, because its ability to provide proper insulation can diminish with age. Other marks like the manufacture date, issue date, or a serial number are useful for tracking and record-keeping, but they don’t indicate whether the insulation is still good to use. The expiration date, on the other hand, directly communicates the safety limit for continued use.