My job involves working around electrical panels, solar equipment, batteries, and similar systems, so my employer provides arc-flash protective clothing. I have a pair of Category 2 pants labeled with an arc rating of 13 cal/cm², but I'm not sure exactly what that rating means. I've also noticed that the pants seem to contribute to static buildup—for example, I sometimes get a small shock after standing up from a couch and touching something else. Is it safe or useful to wear these pants while assembling a desktop PC? Should I leave the power supply connected to a grounded outlet and periodically touch the case, or would it be better to avoid wearing the arc-rated clothing and use a different approach to prevent electrostatic discharge?
3 Answers
The 13 cal/cm² rating describes the approximate incident energy the fabric can withstand before there’s about a 50% chance of a second-degree burn through the clothing. It’s meant for arc-flash protection, not static control, and it’s far more protection than you need for assembling a PC. Build the computer with the power supply disconnected from the wall, and use a properly grounded anti-static wrist strap if you have one. Without a strap, periodically touch an unpainted metal part of the case before handling circuit boards.
Arc-flash clothing is intended for energized electrical work, so it doesn’t replace arc-flash training or provide any special benefit when building a PC. The power supply and case don’t need to be energized during assembly. If you’re unsure about the correct grounding method, follow the strap manufacturer’s instructions or ask your employer’s electrical-safety staff rather than relying on improvised grounding methods.
The arc-rated pants themselves aren’t dangerous to the computer, but if they’re causing noticeable static buildup, they aren’t helping. You can simply wear ordinary clothing, work on a non-carpeted surface, and use an anti-static wrist strap connected according to its instructions. The PC’s power supply should be switched off and unplugged while you install components.
Touching the case only equalizes you with the case, so it’s most effective when the case is connected to a proper ground. A commercial anti-static wrist strap is inexpensive and is the safer, simpler option. Don’t improvise with exposed wires or a plugged-in cable, since that can create a shock hazard.