NESC WORKSHOP Revisions to Part 4 (Work Rules) Sam Stonerock. October 18, 2016

Transcription

1 NESC WORKSHOP 2017 Revisions to Part 4 (Work Rules) Sam Stonerock October 18, 2016

2 Work Rules for the Operation of Electric Supply and Communications Lines and Equipment 2017 edition Reconcile existing rules with FED-OSHA revisions Rule on electric arc exposures / protection - New information addressing hand, head, feet protection - New information for dc systems - New information on 480V arc-in-a-box test results Rule 420K on fall protection - Fall protection to be used at elevated locations above 4 ft. - Appropriate equipment to limit free fall to 2 ft. - Anchorages must support 3000 lb-force - Employees to visually assess anchorages 2

3 Work Rules for the Operation of Electric Supply and Communications Lines and Equipment 2017 edition (continued) Minimum Approach Distances (MAD) - Revise Table (Communication) - Revise Rule Adds rule specific definition for reach / extended reach - Revise rules for voltages above 72.5kV - Revise default Table (Supply) - Add new Tables 441-2, 441-3, ( T has been calc d) - Retain/renumber existing Tables 441-2, 441-3, Minimum clearances for open air gap - New Table for supply stations and OH lines 3

4 Rule 410A3 New / Revised Exceptions EXCEPTION 2: Arc-rated equipment is not necessary for the employee s hands when the employee is wearing rubber insulating gloves with protectors. Heavy-duty leather work gloves with a weight of at least 407 gm/m2 (12 oz/yd2) may be worn if the estimated incident energy is no more than 14 cal/cm2. EXCEPTION 3: Arc-rated equipment is not necessary for the employee s feet when the employee is wearing heavy-duty work shoes or boots. 4

5 Rule 410A3 New / Revised Exceptions EXCEPTION 4: Arc-rated equipment is not necessary for the employee s head or face when the employee is wearing head protection meeting 29 CFR if the estimated incident energy is less than OSHA 9 cal/cm2 for exposures involving single phase arcs in open air less than or 5 cal/cm2 for other exposures. Arc-rated equipment is necessary for the protection of the employee s head and face and may consist of head protection meeting OSHA 29 CFR and a face shield with a minimum arc rating of 8 cal/cm2 if the estimated incidentenergy exposure is greater than 9 cal/cm2 and less than 13 cal/cm2 for exposures involving single-phase arcs in open air or greater than 5 cal/cm2 and less than 13 cal/cm2 for exposures involving single-phase arcs in open air or greater than 5 cal/cm2 and less than 9 cal/cm2 for other exposures. For exposures involving single phase arcs in open air, the arc rating for the employee s head and face protection may be 4 cal/cm2 less than the estimated incident energy. 5

6 New Rule 410A6 / Revised Rule 420Q Antennas 410A6 The employer shall provide training to all employees who work in the vicinity of antennas operating in the range of 3 khz to 300 GHz to recognize and mitigate exposure to radiofrequency sources that exceed exposure levels set forth by the regulatory authority having jurisdiction. NOTE: See OSHA 29 CFR , Subpart G [B67]; OSHA 29 CFR , Subpart R [B68]; FCC Bulletin No. 65 [B32]; IEEE Std C [B61]. 420Q Employees working in the vicinity of antennas operating in the range of 3 khz to 300 GHz shall use controls to mitigate exposure to radio-frequency sources that exceeds permissible exposure levels. NOTE: See Rule 410A6. 6

7 Rule 420K (Fall Protection) 1. Employees shall use appropriate fall protection equipment while climbing, transferring, or transitioning across obstacles on poles or structures, unless doing so not feasible or creates a greater hazard than doing so unattached. a. When work positioning is used, it shall be rigged in a manner in which the employee cannot free fall more than 0.60 m (2 ft). b. Anchorages for work-positioning equipment shall be capable of supporting at least twice the potential impact load of an employee s fall, or 13.3 kn (3000 lb-force), whichever is greater. 7

8 Rule 420K (continued) NOTE 1: Wood-pole fall-restriction devices meeting American Society of Testing and Materials Standard Specifications for Personal Climbing Equipment, ASTM F [Bx] or later versions, are deemed to meet the anchorage-strength requirement when they are used in accordance with manufacturers instructions. NOTE 2: Recognized and generally accepted good engineering practices, with consideration given to such factors as design specifications and maintenance procedures, may be used in determining whether potential anchorages meet the strength requirements in 420K1b provided the employee performs a visual inspection before use that reveals nothing about the appearance of the anchorage (for example, corrosion around support-member connections or bent support members) suggests that the applicable strength criteria would not be met. NOTE 3: On poles, when the employee is transitioning or at the work location and the work positioning strap is positioned above a bolted attachment, step bolt, or other equipment, these attachments may serve as the anchorage. It is not necessary to determine the strength of the attachment provided the employee performs a visual inspection before use that reveals nothing about the appearance of the anchorage (for example, corrosion or cracks) suggests that the applicable strength criteria would not be met. 8

9 Rule 431 / Table

10 Rule A1a A. Minimum approach distance to energized lines or parts 1. General Employees shall not approach or bring any conductive object within the minimum approach distance listed in Table or Table or distances as determined by an engineering analysis to exposed energized lines or parts unless one of the following is met: a. The line or part is de-energized and grounded per Rule 444D. EXCEPTION: For voltages less than 600 V where the making of the ground is impractical, the line or part may be isolated in lieu of installing temporary protective grounds provided the following conditions are met: (a) the lines and equipment are isolated from all sources and tested to be de-energized, (b) there is no possibility of contact with another energized source, and (c) the hazard of induced voltage is not present. 10

11 Rule A1d d. The employee is performing barehand live-line work according to Rule 446. NOTE 1: Minimum approach distances calculated under this rule for kv to kv contain the electrical component plus 0.31 m (1 ft) for inadvertent movement. Voltages kv to 72.5 kv contain the electrical component plus 0.61 m (2 ft) for inadvertent movement. Voltages above 72.5 kv contain the electrical component plus 0.31 m (1 ft) for inadvertent movement. NOTE 2: Methodology for calculating minimum approach distances were taken from 29 CFR Appendix B [B66]. NOTE 3: The voltage ranges are contained in ANSI C , Table 1. NOTE 4: For the purpose of Section 44, reach is defined as the range of anticipated motion of an employee while performing a task, and extended reach is defined as the range of anticipated motion of a conductive object being held by an employee while performing a task. 11

12 Rule 441 (Tables) 441A4 When performing live line work, employees shall position themselves so that they are not within the reach or extended reach of the applicable minimum approach distance. In lieu of using the minimum approach distances in Table 441-1, the minimum approach distance in Table through Table may be used provided the per unit transient overvoltage value (T) has been determined through an engineering analysis considering the system design, expected operating conditions, and control measures. NOTE 1: Control measures include blocking reclosing, prohibiting switching during live line work, using protective air gaps, use of closing resistors and surge arrestors, etc. NOTE 2: IEEE Std [B37] and OSHA 29 CFR Appendix B [B66] contain information that may be used to perform an engineering analysis to determine maximum transient overvoltage factors. The engineering analysis may be performed on a system basis or a per-line basis. 12

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17 Rule 444 / New Table

18 Subcommittee 8 Working Group(s) / 2022 Code Cycle Working Group 8.14 Part 4 Generation Facilities Working Group 8.14 was formed to address possible gaps in Part 4 rules regarding significance to work in generating stations. The kick-off meeting for this WG was held in late August to perform a thorough review of existing rules specifically to assess their relevance to that work. Additionally, a former member of Subcommittee developed a draft Part 5, designed to specifically address work in generating stations. Also, the intent is to deliver the WG s new/revised draft rules to the full Subcommittee for consideration as new (SC8) Change Proposal(s) Working Group 8.XX Part 4 / Part 1 Storage batteries Working Group 8.XX Part 4 / Table Working Group 8.XX Part 4 / New Medium Voltage Arc Flash Table 18