Electrical work carries two distinct hazards that require different protection: electric shock and arc flash. Electrocution remains one of OSHA's construction "Fatal Four" causes of worker death, and arc flash can produce temperatures hotter than the surface of the sun. NFPA 70E, the Standard for Electrical Safety in the Workplace, governs both, and it is built on a clear order of priority: establish an electrically safe work condition first (de-energize and lock out), and use protective equipment only when energized work is unavoidable.
This guide explains the electrical safety equipment the standard requires, how arc-flash PPE categories and incident energy work, the shock approach boundaries, insulating glove classes, lockout/tagout, and how to specify each correctly for compliance.
It is written for electrical engineers, maintenance and reliability teams, and safety and procurement managers responsible for energized-work safety. For non-electrical workplace PPE (head, eye, fall, fire, respiratory), see our broaderindustrial safety equipment list. To source equipment against these standards, browseelectrical safety equipment or send an RFQ.
The Two Electrical Hazards
Electric shock occurs when current passes through the body, causing injury or death. Protection is based on insulation and distance (approach boundaries).
Arc flash is the explosive release of thermal energy when a fault creates an arc, producing extreme temperatures and a pressure wave (arc blast). Protection is based on arc-rated PPE matched to the available thermal energy.
The two are governed by different boundaries and different equipment, so a compliant program addresses both, not just one.
The Hierarchy: De-Energize First
NFPA 70E requires establishing an electrically safe work condition before work begins wherever feasible. Energized work is the exception, permitted only when de-energizing introduces additional hazards or is infeasible, and it then requires an energized electrical work permit. PPE is the last line of defense, not the first, which is why lockout/tagout and verification come before any discussion of arc-rated clothing.
Lockout/Tagout (LOTO) and Verification
LOTO is the procedure and hardware that keeps equipment de-energized during work, governed by OSHA 1910.147 (the control of hazardous energy) and reinforced by NFPA 70E. The equipment:
Locks, hasps, and tags that physically prevent re-energizing and identify who applied them.
Group lockout boxes for multi-worker jobs, so equipment cannot be re-energized until every worker removes their lock.
Voltage testers and proximity testers to verify the absence of voltage after lockout. NFPA 70E requires a test-before-touch step: a non-contact tester confirms presence, and a rated contact tester (or multimeter) confirms the absence of voltage before work begins, with the tester itself proven on a known live source before and after.
Verifying an electrically safe work condition with a properly rated tester is the single step that prevents the majority of serious shock incidents.
Shock Protection: Approach Boundaries and Insulating Equipment
When a circuit cannot be de-energized, shock protection is defined by distance and insulation. NFPA 70E sets approach boundaries around exposed energized parts:
Limited approach boundary: the outer boundary of the shock-hazard zone. Unqualified persons may not cross it unless escorted by a qualified person.
Restricted approach boundary: closer to the energized part, where the increased shock risk requires a qualified person wearing rated shock PPE, and typically an energized work permit.
Rubber Insulating Gloves by Voltage Class
Rubber insulating gloves are the first line of defense against shock when contacting energized parts. They are governed by OSHA 1910.137, which references ASTM D120, and are classified by maximum use voltage. DC ratings are 1.5 times the AC rating for the same class.
Glove Class
Max Use Voltage (AC)
Max Use Voltage (DC)
Label Color
Class 00
500V
750V
Beige
Class 0
1,000V
1,500V
Red
Class 1
7,500V
11,250V
White
Class 2
17,000V
25,500V
Yellow
Class 3
26,500V
39,750V
Green
Class 4
36,000V
54,000V
Orange
Always select gloves rated above the maximum voltage you may encounter, not the voltage you typically work at. Insulating gloves must be worn with leather protectors, require electrical re-testing every six months, and per NFPA 70E all metal jewelry must be removed before donning them, since metal can puncture the rubber or create an arc path.
Other Insulating Equipment
Insulated and insulating tools, required by NFPA 70E 130.7(D)(1) when working on or near exposed energized parts, rated to ASTM F1505 or IEC 60900 for 1000V AC / 1500V DC.
Insulating sleeves, blankets, line hose, and dielectric overshoes for additional coverage on higher-voltage tasks.
Insulated-soled safety footwear as supplementary protection (not a primary shock barrier).
Arc Flash Protection: Incident Energy and PPE Categories
Arc-flash protection is matched to incident energy, the thermal energy a worker could receive at the working distance, measured in calories per square centimeter (cal/cm²). NFPA 70E provides two methods to determine the protection required, and a facility must choose one and apply it consistently:
Incident energy analysis: an engineering calculation (typically using the IEEE 1584-2018 equations) that determines the exact incident energy and arc flash boundary for specific equipment, voltage, available fault current, and clearing time. This is the more precise method.
PPE category method: uses NFPA 70E tables to assign one of four categories based on equipment type and task, valid only when the equipment is within the table's stated fault-current and clearing-time limits. Applying the table outside those limits is a common and dangerous error.
The Four Arc Flash PPE Categories (NFPA 70E 2024)
PPE Category
Minimum Arc Rating
Typical Required PPE
Category 1
4 cal/cm²
Arc-rated shirt and pants or coverall, arc-rated face shield, hard hat, safety glasses, hearing protection, leather gloves and footwear
Category 2
8 cal/cm²
Arc-rated clothing, arc-rated balaclava and face shield (or hood), plus Category 1 items
Category 3
25 cal/cm²
Arc flash suit and hood, arc-rated gloves, all supporting PPE
Category 4
40 cal/cm²
Heavy-duty arc flash suit and hood, multi-layer arc-rated system
A critical safety rule: above 40 cal/cm², NFPA 70E does not permit energized work. No PPE is considered adequate, so the equipment must be de-energized before work begins. The arc flash boundary is the distance from the arc source at which incident energy falls to 1.2 cal/cm², the threshold for a second-degree burn on bare skin; anyone inside it must wear arc-rated PPE appropriate to the incident energy.
Arc-Rated PPE Components
Arc-rated (AR) clothing: flame-resistant shirts, pants, coveralls, and suits with a stated arc rating (in cal/cm²) that must meet or exceed the incident energy. Note that all arc-rated clothing is flame-resistant, but not all flame-resistant clothing is arc-rated.
Arc flash suits and hoods for Category 3 and 4 work.
Arc-rated face shields and balaclavas to protect the head and face.
Arc-rated gloves, used with the rubber insulating gloves above for combined shock and arc protection.
Circuit Protection and Detection Devices
Beyond worker PPE, the installed devices that prevent and limit electrical incidents:
Circuit breakers and fuses interrupt overloads and short circuits. Miniature circuit breakers (MCBs) protect low-voltage circuits; molded-case circuit breakers (MCCBs) handle higher currents.
Ground fault circuit interrupters (GFCIs) cut power on detecting a ground fault, essential in wet locations.
Arc fault circuit interrupters (AFCIs) detect dangerous arcing faults that can ignite fires.
A compliant electrical safety program rests on these standards:
NFPA 70E (Standard for Electrical Safety in the Workplace) defines arc-flash and shock protection, boundaries, PPE, and program structure.
OSHA 29 CFR 1910 Subpart S (and 1910.147 for lockout/tagout, 1910.137 for insulating equipment) sets the federal regulatory requirements NFPA 70E helps satisfy.
IEEE 1584 provides the incident energy calculation methodology.
NFPA 70E requires an arc flash risk assessment that is reviewed when the electrical system changes and at intervals not exceeding five years, with equipment labeled to show incident energy or PPE category, arc flash boundary, and shock approach boundaries.
The Bottom Line
Electrical safety is built on a priority order: de-energize and lock out first, verify the absence of voltage, and use rated equipment only for unavoidable energized work. Address both hazards, shock (approach boundaries, insulating gloves by voltage class, insulated tools) and arc flash (incident energy, arc-rated PPE by category), specify every item to its governing standard, and keep the arc flash risk assessment current. Above 40 cal/cm², the only safe equipment is an open, locked-out disconnect.
Source Electrical Safety Equipment with eINDUSTRIFY
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Frequently Asked Questions
What is the difference between electric shock and arc flash protection?
Shock protection guards against current passing through the body and is based on insulation and approach-boundary distance, using rubber insulating gloves and insulated tools. Arc flash protection guards against the thermal energy of an electrical arc and is based on arc-rated PPE matched to the incident energy in cal/cm². A compliant program under NFPA 70E addresses both hazards separately.
What are the NFPA 70E arc flash PPE categories?
NFPA 70E 2024 defines four categories by minimum arc rating: Category 1 (4 cal/cm²), Category 2 (8 cal/cm²), Category 3 (25 cal/cm²), and Category 4 (40 cal/cm²). Each specifies the arc-rated clothing and PPE required. Above 40 cal/cm², energized work is not permitted and the equipment must be de-energized.
What is the arc flash boundary?
The arc flash boundary is the distance from an arc source at which the incident energy drops to 1.2 cal/cm², the threshold for a second-degree burn on unprotected skin. Anyone working inside this boundary must wear arc-rated PPE appropriate to the incident energy level, determined by an incident energy analysis (IEEE 1584) or the NFPA 70E PPE category tables.
How are rubber insulating gloves rated?
Rubber insulating gloves are classified under ASTM D120 (referenced by OSHA 1910.137) by maximum use voltage, from Class 00 (500V AC) and Class 0 (1,000V AC) for low-voltage work up to Class 4 (36,000V AC) for high-voltage tasks. DC ratings are 1.5 times the AC rating. Gloves must be worn with leather protectors, re-tested every six months, and selected above the maximum voltage you may encounter.
What is lockout/tagout (LOTO) and what equipment does it require?
LOTO is the procedure for controlling hazardous energy during maintenance, required by OSHA 1910.147. It uses locks, hasps, and tags to physically prevent re-energizing, group lockout boxes for multi-worker jobs, and voltage testers to verify the absence of voltage before work. Establishing this electrically safe work condition is required before energized-work PPE is even considered.
What rating must insulated tools meet?
Under NFPA 70E 130.7(D)(1), insulated tools are required when working on or near exposed energized parts and must be rated for the voltage involved, meeting ASTM F1505 or IEC 60900 for 1000V AC / 1500V DC hand tools.
How often must an arc flash risk assessment be updated?
NFPA 70E requires the arc flash risk assessment to be reviewed whenever the electrical distribution system changes and at intervals not exceeding five years. Changes that trigger an immediate review include new equipment or loads, modified upstream overcurrent protection, changes to the utility supply, and any incident or near-miss suggesting the original analysis is inaccurate.
