Rubber Insulating Gloves: OSHA Voltage Classes, Air Testing & Care Guide

Rubber insulating gloves are the frontline personal protective barrier defending electrical workers, linemen, and industrial maintenance technicians against fatal shock, electrocution, and arc flash injuries. Because high-voltage electrical energy can exploit microscopic pinholes, strict adherence to glove classification, daily field testing, and dielectric laboratory re-testing is mandatory.

Direct Safety Takeaway: Under OSHA 29 CFR 1910.137 and ASTM D120, rubber insulating gloves must be rated for the maximum phase-to-phase voltage encountered. They must undergo a visual inspection and manual air test before every shift, always be worn with protective leather outer gloves, and be electrically re-tested in a certified lab at least every 6 months.

OSHA / ASTM Rubber Insulating Glove Voltage Classes

Class	Label Color	Max AC Use Voltage	Max DC Use Voltage	AC Proof Test Voltage
Class 00	Beige	500 V AC	750 V DC	2,500 V AC
Class 0	Red	1,000 V AC	1,500 V DC	5,000 V AC
Class 1	White	7,500 V AC	11,250 V DC	10,000 V AC
Class 2	Yellow	17,000 V AC	25,500 V DC	20,000 V AC
Class 3	Green	26,500 V AC	39,750 V DC	30,000 V AC
Class 4	Orange	36,000 V AC	54,000 V DC	40,000 V AC

Daily Pre-Use Field Inspection: The 3-Step Test

Electrical workers must perform this three-step inspection before every single use:

1. 1. Visual Inspection: Gently stretch the rubber across fingers and palms. Check for punctures, cuts, chemical ozone cutting (cracking along folds), embedded wire particles, and oil degradation.
2. 2. Manual Air Test (The Roll Test): Roll the glove cuff tightly toward the fingers to trap air inside. Listen closely for hissing air leaks, hold the inflated glove against your cheek to feel escaping air, and gently submerge in clean water if pinpoint testing is needed. If air leaks, destroy and discard immediately.
3. 3. Leather Protector Inspection: Inspect outer leather protector gloves for metal shavings, chemical oil saturation, or holes that could puncture the rubber inner glove.

Why Leather Protectors Are Mandatory

Rubber insulating gloves offer high dielectric protection but zero mechanical cut or puncture resistance. Sharp wire strands, burs on conduit, or rough bolts can puncture thin rubber instantly. OSHA mandates that approved leather protector gloves must be worn over rubber insulating gloves at all times, with proper cuff clearance maintained between the leather and rubber cuff:

• Class 00 & Class 0: Minimum 1/2 inch leather-to-rubber cuff distance.
• Class 1: Minimum 1 inch distance.
• Class 2: Minimum 2 inches distance.
• Class 3: Minimum 3 inches distance.
• Class 4: Minimum 4 inches distance.

Dielectric Laboratory Re-Testing Intervals (OSHA Mandate)

Under OSHA 1910.137 Table S-4, rubber insulating gloves must be electrically tested in a certified laboratory:

• Prior to first issue from the manufacturer.
• Every 6 months after being placed into service.
• Every 12 months if stored unused in original packaging.
• Immediately if glove integrity is suspected of being compromised.

5-Minute Safety Talk / Toolbox Topic: Electrical Glove Care

• Meeting Question: “What is the required re-testing interval for rubber insulating gloves in active service?” (Answer: Every 6 months).
• Practical Check: “Verify the lab test date stamped on your glove cuff right now: Is it within the valid 6-month window?”
• Storage Rule: “Always store gloves right-side out in their canvas storage bag — never folded, crushed under tools, or exposed to direct sunlight.”

Daily Electrical PPE Field Checklist

• ☐ Glove voltage class matched to system voltage with adequate safety margin.
• ☐ Certified laboratory test date stamp verified within the past 6 months.
• ☐ Visual check for punctures, cuts, cracking, or chemical degradation completed.
• ☐ Manual roll air test performed — zero air leaks detected.
• ☐ Leather protectors inspected: clean, dry, and free of embedded metal shavings.
• ☐ Gloves stored in a canvas bag away from heat, chemicals, and sharp tools.

Frequently Asked Questions

Can petroleum jelly or standard lotion be used to slip gloves on?

Strictly prohibited. Petroleum-based lotions, oils, and greases chemically degrade natural rubber (known as petroleum rotting), destroying the glove’s dielectric strength. Only use 100% pure cotton glove liners or approved non-petroleum glove powders.

---

Authoritative Sources & Standards

• OSHA 29 CFR 1910.137: Electrical Protective Equipment.
• OSHA 29 CFR 1910.269: Electric Power Generation, Transmission, and Distribution.
• ASTM D120-21: Standard Specification for Rubber Insulating Gloves.
• NFPA 70E: Standard for Electrical Safety in the Workplace.