Personal Protective Equipment for High-Voltage Work

Why PPE Is the Last Line of Defense on High-Voltage Systems

Hybrid and battery-electric vehicles carry high-voltage (HV) systems that typically operate between 100 V DC and 800 V DC or higher. At those voltages, a momentary contact can deliver a lethal shock or cause severe arc-flash burns before a technician can react. Engineering controls—orange cables, HV disconnects, automatic discharge circuits—reduce risk, but they do not eliminate it. Personal protective equipment (PPE) is the final barrier between a technician and electrocution. Selecting, inspecting, and wearing the right PPE correctly every single time is not optional.

The Required PPE Ensemble for HV Work

When you are working on or near an energized HV system—or any time the system has not been verified de-energized and locked out—you must wear the complete ensemble:

• Class 0 rubber insulating gloves with leather protectors
• HV-rated face shield (rated for the voltage and arc energy of the system)
• Arc-rated (AR) / flame-resistant (FR) shirt or outer layer
• Safety glasses worn under the face shield
• Appropriate footwear (leather, non-conductive sole recommended)

No single item substitutes for another. Safety glasses alone do not protect your face from arc flash; leather protectors alone provide no electrical insulation.

Class 0 Rubber Insulating Gloves: What the Rating Means

The American Society for Testing and Materials standard ASTM D120 classifies rubber insulating gloves by their maximum use voltage. Class 0 gloves are rated for use up to 1,000 V AC / 1,500 V DC—the range that covers the vast majority of current automotive HV systems. The classification is stamped or molded into the cuff of every compliant glove along with the manufacturer's name, size, and color-code (beige or tan for Class 0).

Gloves must be factory-tested and field-tested on a regular schedule. The test date and retest due date are printed on a label inside or on the cuff. ASTM D120 sets the maximum retest interval; if the retest date has passed, the gloves must be removed from service and sent for laboratory retesting or destroyed—they may not be used, regardless of their visual condition.

The Pre-Use Inspection Sequence

Perform this inspection every time before donning, in this order:

1. Check dates. Read the manufacture date and the most recent test/retest date on the label. If the retest date has passed, tag the glove OUT OF SERVICE. Do not continue the inspection—defective PPE goes directly to the designated quarantine bin.

2. Visual inspection—exterior. Unroll and examine the entire glove surface in good light. Look for cuts, punctures, embedded debris, ozone cracking (fine surface cracks from UV or chemical exposure), swelling, or discoloration. Any breach of the rubber means the glove is condemned.

3. Visual inspection—interior. Turn the cuff back slightly and look inside for moisture or contamination. Moisture inside reduces insulation value.

4. Air inflation test. Roll the cuff tightly from the opening toward the fingers to trap air inside. The glove should inflate and hold its shape. Watch and listen for at least several seconds. Any deflation, hissing, or visible deformation at a specific spot indicates a leak. Condemn the glove. A calibrated glove inflation tester (a mechanical or electronic device that pressurizes the glove to a specified pressure) provides a more reliable test than hand-rolling and is used in shop settings.

5. Check leather protectors. Inspect for cracks, torn stitching, and sharp embedded objects (metal shavings, staples) that could pierce the rubber glove underneath.

If the glove passes all five steps, it is ready to don.

Donning and Doffing Procedure

Donning (putting on):

1. Put on your FR/AR shirt and safety glasses first.

2. Don the rubber insulating glove on each hand. Seat the glove fully—no bunching at the fingers.

3. Pull the leather protector over each rubber glove. The leather must cover the cuff of the rubber glove; no rubber should be exposed at the wrist.

4. Lower the face shield to the down position before approaching the vehicle's HV components.

Doffing (taking off) — avoid touching the contaminated outer surface:

1. Raise the face shield before removing gloves.

2. Peel the leather protector off without touching the inner surface; set it aside.

3. Remove the rubber insulating glove by grasping only the cuff and pulling it off inside-out.

4. Inspect gloves again after doffing; contaminants acquired during the job may not have been visible before.

5. Store rubber gloves in their individual bags or containers, away from UV light, heat, and ozone sources (such as electric motors).

Responding to Defective PPE

If you discover a defect before use, tag the item with an out-of-service tag and place it in the designated quarantine area. Defects found include:

• Puncture or cut → Condemn; do not retest or repair.
• Expired retest date → Remove from service; send for laboratory retesting per ASTM D120 or replace.
• Cracked cuff or ozone cracking → Condemn.

Never attempt to repair a rubber insulating glove with tape or sealant. There is no field repair for electrical PPE.

Storage and Care

Rubber insulating gloves degrade from UV light, ozone, heat, and contact with oils, solvents, or petroleum products. Store them flat or lightly rolled in their protective bag in a cool, dark location. Keep them away from sharp objects. Log every inspection and use in the shop's PPE tracking log so retest intervals are not missed.