Protection from flames and arcs

The employer must assess every employee who performs work on or near exposed, energized parts of electric circuits for flame and electric-arc hazards. This requirement comes from 1926.960(g)(1) and is explained in Appendix E to Subpart V of Part 1926, which says the employer must identify employees exposed to hazards from flames or electric arcs so they receive required protection.

• Conduct the assessment for each specific employee task involving exposed, energized parts.
• Consider both the likelihood an arc will occur and whether flames could ignite flammable materials in the work area.

(See 1926.960(g)(1).)

The employer must make a reasonable estimate of the incident heat energy (available heat) an employee would be exposed to if an electric arc occurs. This is required by 1926.960(g)(2) and detailed in Appendix E to Subpart V of Part 1926.

• Use a recognized calculation method (for example, IEEE Std 1584, NFPA 70E Annex D, or commercial tools listed in Appendix E) and input parameters such as fault current, arc length, arc-to-worker distance, and clearing time.
• Where parameters vary, use reasonable and, where appropriate, conservative estimates (especially for distance and arc gap) because incident energy falls roughly with the square of distance.
• Avoid methods that are not appropriate for the specific arc type; Appendix E includes a table advising which methods are acceptable for various arc scenarios.

(See 1926.960(g)(2) and Appendix E.)

Employees must wear clothing that will not melt or continue to burn if exposed to flames, and they must wear flame-resistant (FR) clothing when the exposure could cause burn injury. These protections are required by 1926.960(g)(3) and explained in Appendix E to Subpart V of Part 1926.

• Do not allow ordinary clothing made from materials that melt (e.g., some synthetics) in work where flames or arc heat can occur.
• Where incident energy is estimated, choose FR clothing with appropriate arc rating (see 1926.960(g)(5)).
• Layering FR garments is acceptable if the combined system meets the required arc rating.

(See 1926.960(g)(3) and Appendix E: Protection From Flames and Electric Arcs.)

The employer must ensure arc-rated clothing and protective equipment have an arc rating greater than or equal to the estimated incident energy to which the employee would be exposed. This requirement is in 1926.960(g)(5) and further described in Appendix E.

• Use the incident energy in calories per square centimeter (cal/cm2) from your calculation method as the selection benchmark.
• If incident energy is near the rating boundary, select a higher arc rating to account for uncertainties.
• Consider head, face, torso, arms, and legs when selecting PPE; items have different arc ratings and coverage.

(See 1926.960(g)(5) and Appendix E: Protection From Flames and Electric Arcs.)

An employer should consider whether there is a reasonable likelihood an electric arc will occur in the employee's work area by evaluating equipment condition, proximity, tools used, and task type. Appendix E explains these factors under 1926.960(g)(1).

Key factors include:

• Whether energized circuit parts are unguarded or uninsulated and whether conductive objects could contact them.
• If employees are closer than the employer's minimum approach distance (see 1926.960(c)(1)(iii)).
• Whether equipment shows signs of impending failure (arcing, overheating) or has sliding parts that could fault during operation (e.g., racking breakers).
• If employees are working with conductive tools near exposed parts or using open flames.

(See 1926.960(g)(1) and Appendix E: Protection From Flames and Electric Arcs.)

If an employee is closer than the employer-established minimum approach distance, the employee is considered exposed to an electric-arc hazard for assessment purposes. Appendix E explains that proximity closer than the minimum approach distance is a factor indicating exposure under 1926.960(c)(1)(iii).

• Use the employer's minimum approach distance when deciding exposure; even if an employee remains outside the MAD but holds a conductive object that could fall into energized parts, they may still be exposed.
• The MAD should be part of written procedures and training so employees understand safe distances.

(See 1926.960(c)(1)(iii) and Appendix E: Protection From Flames and Electric Arcs.)

Appendix E lists several reasonable methods for estimating incident heat energy, including NFPA 70E Annex D, IEEE Std 1584 (with amendments), and certain commercial tools such as ARCPRO. These are discussed in 1926.960(g)(2) and in Appendix E to Subpart V of Part 1926.

• Appendix E includes a table showing which methods are acceptable for single-phase and three-phase arcs, and notes limitations (for example, certain methods are not acceptable for transformer internal faults or manhole arcs).
• Employers must choose a method appropriate for the arc type and use inputs like fault current, arc length, clearing time, and distance to the worker.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

Estimating the distance is critical because incident energy is approximately inversely proportional to the square of the distance: a small change in distance can greatly change the incident energy exposure. Appendix E emphasizes this in its discussion of 1926.960(g)(2).

• If an employee is very close to an arc, the incident energy can be very high; moving a few centimeters farther away can substantially reduce energy.
• Use realistic working distances and consider equipment enclosures and reach when selecting the distance for calculations (Appendix E includes Table 4).

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

Appendix E's Table 4 lists reasonable distances from the employee to the arc; it suggests about 610 mm (24 in) for low-voltage switchgear and 910 mm (36 in) for 15-kV switchgear. These recommendations are part of the guidance supporting 1926.960(g)(2).

• Use these distances as starting points when estimating incident energy, but adjust based on actual equipment enclosure size and the employee's working position.
• Employers may select other reasonable distances if justified by equipment layout or work practices.

(See Appendix E and 1926.960(g)(2).)

The employer should select an arc gap that reasonably represents the likely sparkover distance or spacing between energized parts; Appendix E gives guidance and tables for selecting arc gaps for different equipment classes under 1926.960(g)(2).

• For single-phase lines, use the dielectric strength of air (~10 kV per inch) to estimate arc gap (e.g., at 50 kV, arc gap ≈ 5 inches).
• For three-phase equipment, use spacing between phases or the arc gap values in Appendix E's Table 5 (for example, 25 mm (1 in) for low-voltage MCCs and panelboards, 152 mm (6 in) for 15-kV switchgear).
• Choose conservative arc gaps when uncertainty exists to avoid underestimating incident energy.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

The methods listed in Appendix E are examples the Occupational Safety and Health Administration will consider reasonable, but employers are free to use other reasonable methods as long as they provide a reasonable estimate of incident energy for the exposure. Appendix E clarifies this under 1926.960(g)(2).

• Employers must justify the chosen method and inputs (fault current, clearing time, arc gap, distance) and show it reasonably represents actual exposures.
• Appendix E warns that some methods may not be appropriate for transformer internal faults or manhole arcs; choose methods suitable for the scenario.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

No; routine operation of properly installed and maintained enclosed equipment without evidence of impending failure is typically not considered an arc exposure. Appendix E's example table supporting 1926.960(g)(1) shows that normal operation of enclosed equipment generally does not require arc-hazard protections unless there is evidence of arcing, overheating, or lack of maintenance.

• If the equipment shows signs like arcing, overheating, loose parts, or damage, then the task becomes an exposure and must be treated accordingly.
• Tasks like servicing, racking breakers, or holding conductive tools near energized parts are examples where exposure is likely.

(See 1926.960(g)(1) and Appendix E: Protection From Flames and Electric Arcs.)

Yes; an employee holding a conductive object that could contact energized parts is considered exposed to an electric-arc hazard. Appendix E's task examples for 1926.960(g)(1) explicitly state that inspection while holding a conductive object is an exposure regardless of whether the minimum approach distance is maintained.

• Avoid holding conductive objects near exposed energized parts or use nonconductive tools/flashlights.
• If conductive tools are necessary, treat the task as an arc-exposure task and provide appropriate FR clothing and PPE.

(See 1926.960(g)(1) and Appendix E: Protection From Flames and Electric Arcs.)

When listed calculation methods are not suitable—such as for internal transformer faults or arcs in underground manholes—the employer must use other reasonable and conservative means to estimate incident energy or apply alternate protective strategies. Appendix E warns that listed methods may not provide full protection for internal transformer faults or manhole arcs in guidance for 1926.960(g)(2).

• Consider conservative assumptions, increased working distances, use of barriers, remote operation, or specialized PPE rated for higher energies.
• Document why the chosen approach is reasonable and protective for the specific, atypical scenario.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

To calculate incident energy, the employer must determine or estimate parameters such as available fault current, arc length (gap), distance from arc to employee, and circuit protective-device clearing time. Appendix E lists these inputs as necessary for methods referenced in 1926.960(g)(2).

• Fault current and clearing time can often be determined from system calculations or protective device specifications.
• Arc length and distance to the employee often require reasonable estimates based on equipment geometry and worker positions.
• Document assumptions and, where uncertainty exists, use conservative values to protect employees.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

Longer clearing times increase incident energy because the arc lasts longer; therefore, clearing time is a critical input and employers must use realistic trip times in calculations. Appendix E highlights clearing time as a key parameter in 1926.960(g)(2).

• Use manufacturer or system data for device trip curves when available.
• If using estimated trip times, choose conservative (longer) values when uncertainty exists to avoid underestimating energy exposure.
• Recognize that using faster protective devices or reducing fault current can meaningfully reduce calculated incident energy.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

Equipment enclosure size affects how far an arc can expand within the enclosure and influences the reasonable distance selected from the employee to the arc; Appendix E directs employers to consider enclosure size when choosing a distance in support of 1926.960(g)(2).

• Larger enclosures can allow arcs to develop differently and may change the effective distance from the arc to where a worker stands.
• Use Appendix E's Table 4 distances as guidance but adjust based on enclosure geometry, work position, and likely arc trajectory.
• Document the rationale for the chosen distance and how enclosure size was considered.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

If the assessment shows there is no significant burn hazard or the incident energy is below levels that would ignite or melt clothing, non-FR clothing may be acceptable; however, the employer must document the assessment and ensure clothing will not ignite or melt under the estimated exposure per 1926.960(g)(3). Appendix E explains that clothing must not melt or continue to burn when exposed to flames or the estimated heat energy.

• For exposures above minimal energy levels (commonly compared to 2.0 cal/cm2 thresholds used in guidance), employers generally select FR clothing with an appropriate arc rating.
• When in doubt or when the task could change, choose FR clothing or take administrative controls to reduce exposure.

(See 1926.960(g)(3) and Appendix E: Protection From Flames and Electric Arcs.)

No; employers are not required to use IEEE Std 1584b-2011 specifically, but Appendix E lists IEEE Std 1584b-2011 as an acceptable method for many arc types; employers may use any reasonable method appropriate to the exposure as required by 1926.960(g)(2).

• Appendix E's table indicates IEEE Std 1584b-2011 is acceptable for a range of arc types and provides guidance on applicability and limitations.
• Employers should choose a method that fits the arc scenario and document why it is reasonable; some methods may be conservative or inappropriate for certain arcs.

(See 1926.960(g)(2) and Appendix E: Protection From Flames and Electric Arcs.)

Yes; using open flames in tasks (for example, wiping cable splice sleeves) creates a flame hazard and employees performing those tasks must be assessed and provided appropriate protection, including non-melting and flame-resistant clothing when needed, as explained in Appendix E under 1926.960(g)(1).

• Treat open-flame tasks as exposures and control ignition sources, remove flammables, and provide flame-resistant PPE if there's a burn risk.
• Document the assessment and controls taken to protect employees from both flame and potential arc hazards.

(See 1926.960(g)(1) and Appendix E: Protection From Flames and Electric Arcs.)

Yes — an employer may make broad, conservative incident-heat-energy estimates that cover multiple system areas instead of calculating every single task. Appendix E explains that 1926.960(g)(2) permits employers to use reasonable assumptions about how energy is distributed and to use estimates that represent the maximum exposure for those areas (for example, using maximum fault current and clearing time to cover several system areas).

• Use conservative assumptions (maximum fault current and clearing time) so the estimate bounds actual exposures.
• Document the assumptions and show they represent the maximum exposure for the covered areas.

Cited: 1926.960(g)(2) and Appendix E guidance (1926 Subpart V App E).

Arc-rated clothing is required when the estimated incident heat energy is above 2 cal/cm²; arc-rated protection is not required for exposures of 2 cal/cm² or less. Appendix E explains that 1926.960(g)(5) requires employers to select protective clothing with an arc rating greater than or equal to the estimated incident energy, and it explicitly states the rule does not require arc-rated clothing when exposures are 2 cal/cm² or less.

• When estimated energy ≤ 2 cal/cm²: arc-rated clothing is not required, but other garment requirements (flame-resistant outer layer, restrictions on certain undergarment fabrics, and prohibited non‑FR logos) may still apply under 1926.960(g)(3)–(g)(4).

Cited: 1926.960(g)(5) and Appendix E (1926 Subpart V App E).

Rubber insulating gloves with protectors or heavy-duty leather work gloves may be acceptable in place of arc-rated gloves when the estimated incident energy falls within specified limits. 1926.960(g)(5)(i) allows non‑arc‑rated hand protection when either (a) the estimated incident heat energy does not exceed 14 cal/cm² and the employee is wearing rubber insulating gloves with protectors, or (b) the employee is wearing heavy‑duty leather work gloves that weigh at least 407 g/m² (12 oz/yd²).

• Verify the incident-energy estimate before relying on these exceptions.
• Keep records showing glove type, weight (for leather), and the estimated energy for the task.

Cited: 1926.960(g)(5)(i) and Appendix E (1926 Subpart V App E).

Yes — heavy‑duty work shoes or boots are acceptable as non‑arc‑rated foot protection under the standard. 1926.960(g)(5)(ii) states that arc‑rated protection for the feet is not required when the employee is wearing heavy‑duty work shoes or boots.

• Ensure footwear is heavy‑duty and appropriate for electrical work (no melting/flammable materials).
• Maintain other body protection per 1926.960(g)(5).

Cited: 1926.960(g)(5)(ii) and Appendix E (1926 Subpart V App E).

You must provide minimum arc-rated head and face protection based on the type of exposure and estimated incident energy ranges shown in [1926.960(g)(5)(iii)–(v)]. The table in Appendix E summarizes the required minimums: for single‑phase open‑air exposures, face protection ranges are: 2–8 cal/cm² => faceshield (min 8 cal/cm²); 9–12 cal/cm² => faceshield with balaclava; 13+ cal/cm² => arc‑rated hood or faceshield with balaclava (with hardhat meeting [1910.135] standards assumed). For three‑phase, the ranges are shifted (e.g., 2–4, 5–8, 9+ cal/cm² bands). See 1926.960(g)(5)(iii), 1926.960(g)(5)(iv), and 1910.135 for hardhat specs.

• The table assumes employees wear hardhats that meet 1910.135 or 1926.100(b)(2).
• For higher incident energies, combine face protection with an arc‑rated hood as required.

Cited: 1926.960(g)(5)(iii), 1926.960(g)(5)(iv), and 1910.135.

Arc‑rated protection must cover the employee's entire body except for limited allowed exceptions for the hands, feet, face, and head described in the standard. Appendix E states that 1926.960(g)(5) requires arc‑rated protection to cover the whole body, with limited exceptions addressed by 1926.960(g)(5)(i)–(v).

• When relying on exceptions (e.g., rubber insulating gloves, heavy‑duty boots), ensure other PPE and estimations support the exception.
• Ensure outer layers are flame resistant as required by 1926.960(g)(4).

Cited: 1926.960(g)(5) and Appendix E (1926 Subpart V App E).

Use the voltage range, next‑higher fault current and the clearing‑time column in Table 6 to read the incident‑energy band and then pick PPE with an arc rating at or above the next rating level. Appendix E gives an example: a 12,470‑volt line (4.0–15.0 kV range) with maximum fault current 8 kA and clearing time 10 cycles falls under the 4 cal/cm² category in Table 6; selecting PPE rated at 5 cal/cm² will meet 1926.960(g)(5). See 1926.960(g)(2) for using the next‑higher table values.

• Choose the next‑higher fault‑current and clearing‑time entries in the table when matching a system to a table row/column.
• Document the voltage, maximum fault current, and maximum clearing time used for selection.

Cited: 1926.960(g)(2) and 1926.960(g)(5) (Table 6 guidance) and Appendix E (1926 Subpart V App E).

Table 6 assumes the arc length equals the sparkover distance for the maximum transient overvoltage of that voltage range and the worker is 380 mm (15 in.) from the arc. Appendix E states these assumptions and explains the sparkover distances used for each voltage band (e.g., 4.0–15.0 kV => 51 mm or 2 in.). See 1926.960(g)(2) and Appendix E guidance.

• If your work conditions differ (closer/farther distance or different arc length), you must use other calculation methods (see Table 2/3 or IEEE Std 1584b–2011).

Cited: 1926.960(g)(2) and Appendix E (1926 Subpart V App E).

An employer may use IEEE Std 1584b–2011 to estimate available heat energy for many specific conditions not covered exactly by Appendix E tables, including lower‑voltage phase‑to‑phase arcs and enclosed arcs. Appendix E explicitly recommends using [IEEE Std 1584b–2011] as an accepted method for many specific conditions and to select appropriate PPE. See Appendix E and 1926.960(g)(2).

• If using IEEE methods, document inputs, assumptions, and results to show compliance with 1926.960(g)(5).

Cited: 1926.960(g)(2) and Appendix E (1926 Subpart V App E).

Table 7 assumes the worker will be located at the minimum approach distance minus twice the sparkover distance from the electric arc. Appendix E explains that Table 7 estimates are based on that distance assumption and the arc length equaling the sparkover distance for the maximum phase‑to‑ground voltage of each range. See 1926.960(g)(2) and Appendix E.

• If your actual working distance differs, you must use other calculation methods (e.g., IEEE Std 1584b–2011 or ARCPRO) to estimate incident energy.

Cited: 1926.960(g)(2) and Appendix E (1926 Subpart V App E).

You may use Appendix E tables for voltages above 72.6 kV only when the system's minimum approach distance under 1926.960(c)(1) is greater than or equal to the specific minimums listed in Appendix E for each voltage band (for example, 1.02 m for 72.6–121.0 kV). Appendix E lists the required minimum approach distances for each high‑voltage band and limits use of the tables accordingly.

• If the actual minimum approach distance is smaller than the listed value, use calculation methods instead of the table for accurate incident‑energy estimates.

Cited: 1926.960(c)(1) and Appendix E (1926 Subpart V App E).

Yes — Appendix E explains an employer can select a base incident‑energy value (e.g., 8 cal/cm²) and confirm that no system area's clearing time exceeds the maximum clearing time listed for that arc‑rating column in the table. If clearing times are within the table limits for the voltage and fault‑current, the chosen arc rating is acceptable under 1926.960(g)(5).

• This is a practical way to verify a chosen PPE rating covers multiple system areas when table conditions match your system.

Cited: 1926.960(g)(5) and Appendix E (1926 Subpart V App E).

Appendix E states that protective clothing with an arc rating equal to the estimated incident heat energy is expected to prevent second‑degree burns under lab test conditions, but actual exposures can vary and an ATPV‑based arc rating gives only a 50% chance of just avoiding second‑degree burns. Appendix E explains these limitations and that reasonable employer estimates and maintaining minimum approach distances should limit severe burns. See 1926.960(g)(5).

• Recognize ATPV statistical nature: at the arc rating level there is roughly a 50% chance of just receiving a second‑degree burn (per ASTM F1506 testing assumptions).
• Consider adding conservatism (higher arc‑rating) where practical and document risk‑based decisions.

Cited: 1926.960(g)(5) and Appendix E (1926 Subpart V App E).

Employees must avoid undergarments made of fabrics that can melt or ignite easily, even when the outer layer is flame‑resistant or arc‑rated. Appendix E warns that certain fabrics listed in the note to 1926.960(g)(3) (e.g., some synthetics that can melt) can increase burn severity and therefore must not be worn beneath protective outerwear. Also, non‑FR logos or name tags can adversely affect the protection.

• Require workers to wear permitted undergarment materials and prohibit melting/flammable fabrics.
• Prohibit non‑FR logos, name tags, or attachments that could reduce garment performance.

Cited: 1926.960(g)(3), 1926.960(g)(4), and Appendix E (1926 Subpart V App E).

Appendix E recommends using the calculation methods listed in Table 2 and the guidance in Table 3, or standards such as IEEE Std 1584b–2011, to estimate available heat energy for situations not covered by Table 6 or Table 7. The Appendix explicitly points employers to those calculation methods and to 1926.960(g)(2) for estimating incident‑energy in non‑tabulated conditions.

• Document which calculation method or standard you used, inputs, and results to show compliance with 1926.960(g)(5).

Cited: 1926.960(g)(2) and Appendix E (1926 Subpart V App E).

Yes — Appendix E states that untreated cotton clothing will reduce a 2 cal/cm² exposure below the heat level needed to cause burns and that such cotton should not ignite at these low energy levels. However, Appendix E also reminds employers that 1926.960(g)(4) may still require a flame‑resistant outer layer under some conditions even when estimated incident energy is ≤ 2 cal/cm².

• Even when cotton is acceptable, avoid prohibited undergarment fabrics and non‑FR attachments.

Cited: 1926.960(g)(4) and Appendix E (1926 Subpart V App E).

Under 1926.960(g)(3), employers must prohibit meltable fabrics and other clothing that could melt onto an employee’s skin or ignite and continue to burn. Examples of fibers to avoid include acetate, nylon, polyester, and polypropylene — even when they are blended with other fibers. See 1926.960(g)(3) and the guidance in 1926 Subpart V Appendix E which explains that melting fibers can adhere to skin, transfer heat rapidly, worsen burns, and complicate medical treatment.

Under 1926.960(g) and Appendix E, untreated cotton is generally acceptable only for incident energy exposures of 2.0 cal/cm² or less. If estimated incident energy exceeds 2.0 cal/cm², the employer must provide flame-resistant clothing with an appropriate arc rating in accordance with 1926.960(g)(4) and 1926.960(g)(5). See the discussion in 1926 Subpart V Appendix E for context on the 2 cal/cm² threshold.

Under 1926.960(g)(4), an employee must wear flame-resistant outer clothing regardless of the 2 cal/cm² threshold when any of these conditions apply: (1) the employee may contact energized circuit parts operating at over 600 volts (1926.960(g)(4)(i)); (2) an electric arc could ignite flammable material in the work area that could, in turn, ignite the employee’s clothing (1926.960(g)(4)(ii)); or (3) molten metal or arcs from faulted conductors in the work area could ignite the employee’s clothing (1926.960(g)(4)(iii)). See 1926 Subpart V Appendix E for examples and further explanation.

Under 1926.960(g)(3), if an outer flame-resistant layer could suffer a breakopen (a hole, tear, or crack that no longer blocks incident heat), then the next inner layer must be flame-resistant if it could ignite. The employer must consider the possibility that an inner, non-flame-resistant layer could become exposed and pose an ignition hazard. See 1926.960(g)(3) and the explanation in 1926 Subpart V Appendix E about breakopen and layering.

Under the Appendix E guidance, an employer can estimate arc length in millimeters by multiplying the phase-to-ground voltage in kilovolts by 2.54, because the dielectric strength of air is about 10 kilovolts per inch (1 inch = 25.4 mm). This relationship is described in 1926 Subpart V Appendix E and discussed alongside the requirements in 1926.960. The appendix also notes employers may use English units if preferred, while recognizing metric calculations were used in OSHA’s tables.

Under Appendix E, the arc thermal performance value (ATPV) is defined as the incident energy (in cal/cm²) that gives a 50% probability that heat transfer through the tested material will cause onset of a second-degree skin burn, based on ASTM F1506 and the Stoll heat-transfer curve. Employers use ATPV (also called arc rating) to select protective clothing whose rating is equal to or greater than the estimated incident energy so the clothing reduces the likelihood of second-degree burns. See 1926 Subpart V Appendix E and the requirements in 1926.960(g)(5).

Yes. Appendix E explains that meltable fabrics can be hazardous even when not directly next to the skin because melted fibers can adhere to skin, transfer heat rapidly, worsen burns, and complicate treatment. Therefore, meltable fabrics (e.g., acetate, nylon, polyester, polypropylene) must be avoided under 1926.960(g)(3) and the related guidance in 1926 Subpart V Appendix E.

Under 1926.960(g)(3), employees may not wear flammable clothing in conjunction with flame-resistant clothing if the flammable clothing poses an ignition hazard. If an outer FR layer could expose a flammable inner layer (for example, through openings or breakopen), the inner layer must be flame-resistant. See 1926.960(g)(3) and the Appendix E discussion in 1926 Subpart V Appendix E for examples and guidance.

Under 1926.960(g)(5)(v) and Appendix E, employers may use certain types of head and face protection whose arc rating is at least 4 cal/cm² less than the estimated incident energy; Appendix E specifically notes that 1926.960(g)(5)(v) permits this type of head and face protection and that 1926.960(g)(5) permits such protection at any incident energy level. Employers should follow the exact conditions in the standard when using lower-rated head/face gear; see 1926.960(g)(5)(v) and 1926 Subpart V Appendix E for details.

Under 1926.960(g)(4)(ii), if an electric arc could ignite flammable material in the work area that, in turn, could ignite the employee’s clothing, the employer must require flame-resistant clothing as an outer layer. The rule specifically lists this scenario as one of the conditions that trigger the need for FR clothing regardless of the 2 cal/cm² threshold; see 1926.960(g)(4)(ii) and the Appendix E discussion in 1926 Subpart V Appendix E.

Yes. Appendix E tells employers they must consider grounding conductors that might not be capable of carrying fault current without failure (for example, static wires or pole grounds) as possible sources of electric arcs when determining whether clothing could ignite under 1926.960(g)(4)(iii). Appendix E also notes that grounds capable of carrying the maximum available fault current are not a concern and need not be treated as arc sources. See 1926 Subpart V Appendix E for the full explanation.

Under 1926.960(g)(5), employers must provide protective clothing and equipment with an arc rating greater than or equal to the employer’s estimate of available incident energy; when the estimate exceeds 2.0 cal/cm², flame-resistant clothing with a suitable arc rating is required as the outer layer in accordance with 1926.960(g)(4) and 1926.960(g)(5). Appendix E explains how ATPV (arc rating) correlates to the likelihood of second-degree burns; see 1926 Subpart V Appendix E for guidance on selecting clothing and ratings.