511 EM 385-1-1 Chapters 9-15

Sections

11-8. General Requirements.

General Electrical Safety

All electrical wiring and equipment must be NRTL-listed or approved and labeled by the AHJ.
Electrical work must comply with NESC, OSHA, and USCG requirements, or host nation's requirements where applicable.
Adhere to the most stringent design safety standards in 29 CFR 1910, 29 CFR 1926, NESC, and NFPA70.

Electrical Hazard Risk Assessments

Conduct shock and arc flash risk assessments to identify and mitigate hazards.
Use shock risk assessments to determine voltage exposure, approach distances, and required PPE or insulated equipment.
Use arc flash risk assessments to identify safe work practices, arc flash boundaries, and necessary PPE.

Shock Risk Assessment Specifics

Define Limited Approach Boundary and ensure Unqualified Persons do not cross it without guidance from a Qualified Person.
Define MAD (Minimum Approach Distance) and ensure Qualified Persons maintain distance unless properly insulated or guarded.
Document assessments in the AHA, including identifying shock hazards and determining protective measures.

Arc Flash Risk Assessment and Equipment Labeling

Select arc flash PPE using Incident Energy Analysis or Arc Flash PPE Category Method and label equipment with shock and arc flash hazards.
Labeling must include system voltage, approach limits, arc flash boundary, and PPE information.
Provide physical or mechanical barriers to designate arc flash and electrical shock boundaries, ensuring barriers are outside the limited approach or arc flash boundary.

Tool and Barrier Requirements

Use insulating tools that comply with 29 CFR 1910.137 for work on energized equipment.
Install barriers or designate boundaries for arc flash and shock hazards prior to electrical work.

Knowledge Check Choose the best answer for the question.

11-9. What should be used to identify safe electrical work practices, arc flash boundaries, and necessary PPE?

Stringent design safety standards

A shock risk assessment

Arc flash risk assessments

Define Limited Approach Boundary (LABs)

You forgot to answer the question!

EM 385-1-1 Paragraph 11-8 (a.–b.).

11-8. General Requirements (a.–b.).

a.  General. (11-8.a)

(1)  All electrical wiring and equipment must be a type listed by a NRTL for the specific application for which it is to be used.  For equipment not listed by a NRTL, the AHJ must determine if use is allowable.  The AHJ must inspect, approve, and label safe for use all electrical equipment not a type listed by a NRTL.

Note. Examples of non-NRTL equipment would be IEC rated but not NEMA rated products, “CE” marked equipment covered by Declarations of Conformity to European Union (EU) directives and European Standard (EN) standards, or USACE constructed control panels that would fall under the UL-508A listing that are used only at the facility where they are constructed.

(2)  Excavation and Trenching.  See chapter 25 for utility verification and work activity procedures.

(3)  All electrical work must comply with applicable NESC (for example, NESC, NFPA70, NFPA 70E, NFPA 70B), OSHA, and USCG requirements (see paras 11-3 and 11-4).  If the requirements of this chapter differ with the above requirements, the AHJ will determine, approve, and document the basis for which code or standard applies to the work based on the requirements.

Note. When working OCONUS, all electrical work must comply with either the host nation’s requirements, NFPA70 (NEC) or IEEE-C2 (NESC), or BSI BS 7671.  In general, the host nation requirements will be used in countries with an existing electrical code, NFPA 70 (NEC) or IEEE- C2 (NESC) will be used in countries where 60 Hz power is predominant and the country does not have an established electric code, and BSI BS
    7671 will be used in countries where 50 Hz power is predominant and where no electric code exists.

(4)  Comply with the design safety standards for electrical systems included in 29 CFR 1910 and 29 CFR 1926 for all work covered by this chapter.

(5)  Comply with the design requirements included in the NESC and NFPA70 for all work performed and covered by the scope of these two standards.

(6)  Comply with the more stringent design specifications included in contract unless they violate OSHA requirements.

b.  Electrical Hazard Risk Assessments.  Conduct shock and arc flash risk assessments, at a minimum, to identify safety-related work practices prior to any electrical hazard exposure.  Document the results in the AHA.  (See para 11-6)  (11-8.b)

(1)  Shock Risk Assessment.  A shock risk assessment is used to identify the shock hazards, estimate the likelihood and severity of an injury occurring, and determine whether additional protective measures (for example, engineering controls, PPE) are necessary. The shock risk assessment must include the following:

(a)  Use the shock risk assessment to determine the voltage that personnel might be exposed to, the approach distances, and any PPE or insulated equipment needed to protect against the hazard.

(b)  Limited Approach Boundary.  The limited approach boundary must be defined in each shock risk assessment (see tables 11-1 and 11-2).

(b-1)  When Unqualified Persons are working at or near the limited approach boundary, the QP in charge of the work must identify the electrical hazards and warn them of the boundary.

(b-2)  An Unqualified Person must not cross inside the limited approach boundary of energized conductors or circuit parts unless there is a need in which the QP must instruct them on the hazards present and continuously escort them while inside the boundary.

(c)  MAD (Restricted Approach Boundary).  The MAD must be defined in the shock risk assessment. The MAD lies inside the limited approach boundary (see table 11-3). A QP must not approach or take a conductive object closer than the MAD unless:

(c-1)  The QP is insulated or guarded from energized electrical conductors or circuit parts operating at 50 volts or more.  Insulating gloves and sleeves are considered insulation only with regards to the energized parts upon which work is performed; or

(c-2)  The energized electrical conductors or circuit parts are insulated from the
            QP and from any other conductive object at a different potential.

(2)  Arc Flash Risk Assessment.  An arc flash risk assessment is used to identify the arc flash hazards, estimate the likelihood and severity of an injury occurring, and determine whether additional protective measures (for example, PPE) are necessary.

(a)  Use the arc flash risk assessment to determine the appropriate safety-related work practices, the arc flash boundary, the working distance, and any PPE to be used within the arc flash boundary.

(b)  Arc Flash PPE.  Select arc flash PPE using one of the following methods, but not both:

(b-1)  Incident Energy (IE) Analysis.  An IE Analysis uses short circuit, coordination, and arc flash studies to determine the IE for a given operating condition at a piece of equipment. The analysis method must account for the overcurrent device characteristics as well as the fault clearing time and condition of maintenance.  Use NFPA 70E table 130.5(G) to identify the arc flash PPE when the IE analysis method is used. Unless it is part of the scope of the current contract, the responsibility for the IE Analysis usually lies with the host employer or system owner.

(b-2)  Arc Flash PPE Category Method.  If an IE Analysis is not performed by the contract employer or provided by the host employer or system owner, use NFPA 70E table 130.7(C)(15)(a) to determine the arc flash PPE category for AC equipment or NFPA 70E table 130.7(C)(15)(b) for DC equipment.  The tables include maximum fault currents, maximum clearing times, and minimum working distances for determining the PPE category. When equipment exceeds these ratings, an IE analysis must be performed. When the arc flash PPE category has been determined from the appropriate table, use NFPA 70E table 130.7(C)(15)(c) to identify the PPE appropriate for the task.

Note. Prior to commissioning new equipment, the Category Method must be used if an IE Analysis is not performed.  The Category Method cannot be used if the parameters for use of the tables are not met.  All temporary construction power distribution equipment must have the PPE Category indicated prior to initial energization.

(c)  Equipment Labeling.  Labels must be placed on energized equipment that is likely to require examination, adjustment, servicing, or maintenance while energized. Labels are required to warn of potential shock and arc flash hazards.  Unless it is part of the scope of the current contract, the responsibility for labeling usually lies with the host employer or system owner.  Labels must include the following:

(c-1)  Nominal system voltage.

(c-2)  Limits of approach.

(c-3)  Arc flash boundary.

(c-4)  At least one of the following from c-5 through c-7:

(c-5)  Available IE and the working distance or the arc flash PPE category based on NFPA 70E Table 130.7(C)(15)(a) or Table 130.7(C)(15)(b) for the equipment, but not both.

(c-6)  Minimum arc rating of clothing.

(c-7)  Site-specific level of PPE.

(3)  Physical or Mechanical Barriers.  Provide suitable temporary barriers or other means to designate arc flash and electrical shock boundaries.  Install the barriers no closer than the limited approach boundary or arc flash boundary, whichever is the greater distance. Boundaries must ensure that a workspace cannot be used as a passageway while electrical work is being performed.  Barriers must be installed prior to performing work that exposes workers to electrical hazards.

(4)  Insulating Tools.  All insulating tools used to protect employees from electrical hazards must comply with 29 CFR 1910.137 and chapter 5 of this manual.  Properly rated insulating tools must be used when working on energized equipment when there is a risk of the tool contacting another energized conductor or grounded conductive objects.