501 EM 385-1-1 Construction Safety Hazard Awareness for Contractors Sections 7 - 13

11.B Arc Flash.

11.B.01 Whenever work on or near energized parts greater than 50 volts is necessary, a hazard analysis/arc flash hazard analysis will be conducted in accordance with NFPA 70E. Either Appendices or Tables may be used to conduct the analysis. The flash protection boundary, approach distances, hazard/risk category and personal protective equipment (PPE) requirements must all be identified.

11.B.02 PPE that provides appropriate arc flash protection is required for all personnel working on or near exposed energized electrical equipment operating at 50 volts or more. Identification of required PPE is based on equipment arc flash labels or NFPA 70E task tables. > See Section 05.I.

11.B.03 PPE garments must meet and be labeled in accordance with ASTM F1506, Standard Specification for Flame Resistant Textile Materials for Wearing Apparel for use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards.

11.B.04 Arc rated clothing must be properly worn. Long sleeves must be rolled down and buttoned, shorts are prohibited and trousers must extend the full length of the leg. Garments with exposed metallic fasteners must not be worn unless the garments are properly arc rated.

11.B.05 Garments, to include fall protection harnesses, worn over arc rated protective clothing, must also be arc rated.

11.B.06 Clothing that could increase the extent of injuries when exposed to electric arcs or open flames (i.e., acetate, nylon, polyester, rayon or any blend, celluloid or other flammable plastic), must not be worn. No metal slides or zippers unless they are effectively covered.

11.B.07 Arc flash labels must be placed on energized equipment. Labels are required to warn of potential arc flash hazards and appropriate PPE. Labels, at minimum, must include:

1. Limits of approach;
2. Nominal system voltage;
3. Hazard/Risk category (required PPE);
4. Incident energy at working distance.

11.B.08 All personnel entering the identified arc flash protection boundary must be QPs and properly trained in NFPA 70E requirements and procedures. Unless permitted by NFPA 70E, Article 130.4, no Unqualified Person must be permitted to approach nearer than the Limited Approach Boundary of energized conductors and circuit parts. Training must be administered by an electrically qualified source and documented.

11.C Overcurrent Protection, Disconnects and Switches.

11.C.01 All circuits must be protected against overload.

1. Overcurrent protection must be based on the current-carrying capacity of the conductors supplied and the power load being used.
2. No overcurrent device must be placed in any permanently grounded conductor except where the overcurrent device simultaneously opens all conductors of the circuit or where the device is required by NEC 430 for motor overload protection.
3. Overcurrent protection devices must be readily accessible, clearly labeled, not exposed to physical damage, not placed in the vicinity of easily ignitable materials, and located or shielded such that their operation will not expose employees to injury due to arcing or the sudden movement of parts.
4. Circuit breakers must clearly indicate whether they are in the open (de-energized/off) or closed (energized/on) position.
5. Enclosures containing overcurrent protective devices must be provided with lockable, close-fitting doors.
6. Access and working space must be provided and maintained around all electrical equipment to permit ready and safe operation and maintenance in accordance with NFPA 70, Article 110.26, Spaces About Electrical Equipment. Where required clearance is not feasible (i.e., floating plant, vessels, etc.), procedures must be in place to ensure sufficient clearance is maintained for fully opening the door and/or servicing the electrical enclosure.

11.C.02 Disconnects.

1. Disconnecting means must be located or shielded so that persons will not be injured when the disconnect is operated.
2. Enclosures for disconnecting means must be securely fastened to the surface and fitted with covers.
3. Disconnecting means must be capable of accepting a lock and of being locked in the open (de-energized/off) position.

11.C.03 Switches.

1. A readily accessible, manually-operated switch must be provided for each incoming service or supply circuit.
2. Switches must be of the externally operable type mounted in an enclosure listed for the intended use and installed to minimize the danger of accidental operation.

11.C.04 Switches, fuses, and automatic circuit breakers must be marked, labeled, or arranged for ready identification of the circuits or equipment that they supply.

11.C.05 Switches, circuit breakers, fuse panels, and motor controllers located outdoors or in wet locations must be in a listed weatherproof enclosure or cabinet.

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