Mitigating Induced AC Voltage during Construction by cCG8De4w


									                                                                  Section:         C1280
                                                                  Title:           Mitigating Induced AC Voltage during
CONSTRUCTION STANDARDS                                            Revised:         7-1-2005

Table of Contents
1. Scope..................................................................................................................................... 1
2. Mitigating Induced AC Voltage during Construction................................................................ 1

     1. Scope
         This document defines Company requirements for Mitigating Induced AC Voltage during

     2. Mitigating Induced AC Voltage during Construction
           2.1.       The Contractor shall ensure that all persons engaged in construction work are instructed
                      on induced AC voltage conditions and concerns. Contractor’s representatives shall
                      attend Company-sponsored pre-job briefings on project safety requirements. In addition,
                      Contractor’s representatives shall familiarize themselves with these standards and the
                      Company Contractor Safety Manual. Contractor’s supervisory personnel shall train all
                      workers and maintain staff fluency in current safety requirements and Company policies.
           2.2.       On a daily basis, Contractor shall obtain:
                          Weather conditions/information (from National Weather Service)
                          Scheduled power line changes (from the electric power system Operator)
                      At all times, Contractor shall ensure that automatic re-closer devices are deactivated
                      during the pipeline construction period.
           2.3.       Grounding crews shall be staffed by personnel who, by training and experience, are
                      familiar with and can carry out mitigative procedures specified in applicable codes and
                      standards. All personnel working in an area of high-voltage power lines shall be
                      instructed to minimize contact with metallic equipment. The Company may provide
                      Inspectors (that report to the Company Representative) to inspect grounding procedures.
           2.4.       Each member of each grounding crew shall be equipped with rubber insulating gloves
                      and mitts in conformance with applicable codes and standards. Gloves shall be
                      inspected daily. Torn or otherwise defective gloves shall be discarded. Each grounding
                      crew shall be equipped with Contractor-supplied instrumentation for measuring induced
                      voltages and currents.
           2.5.       Temporary and permanent grounding is not intended to mitigate voltages arising from
                      lightning or power line faults. As such, all pipeline contact work may be halted during
                      inclement weather. The Company Representative shall decide when work will be
                      stopped. Unless otherwise specified, work will be stopped when one or more of the
                      following conditions occur:
                          During local electrical storms denoted by visible lightning or the sound of thunder
                          During high winds, wet snow, or freezing rain
                          During scheduled switching on the electric power transmission system
                          When Contractor fails to comply with specified grounding procedures
           2.6.       Prior to performing pipeline work, Contractor shall monitor pipe-to-ground voltages where
                      AC power lines have line-to-ground voltages greater than 35 KV and where a:
                  2.6.1. Pipeline is located on a power line right-of-way (ROW)
                  2.6.2. Pipeline ROW is located parallel to a power line ROW with adjacent boundaries at or
                           within three 300 feet of each other
                  2.6.3. Pipeline extension (in conformance with paragraphs 2.6.1 or 2.6.2 (above)) is located
                           within 1,500 hundred feet of an entrance or exit from a power line ROW (distance
                           measured perpendicular from the centerline of nearest power line)

Highlighting indicates revisions made as of the date on this standard.                                                          Page 1 of 3
                                                 Section:      C1280
                                                 Title:        Mitigating Induced AC Voltage during
CONSTRUCTION STANDARDS                           Revised:      7-1-2005

        2.7.    Prior to any activity involving pipe contact work, grounding crews shall measure the pipe-
                to-ground voltage. Contractor shall communicate with electric power line operator to
                determine the minimum safe clearance (from power lines) for operation of overhead
                equipment (e.g.: cranes or sidebooms) within the power line ROW. Where necessary to
                prevent electrical contact or arcing to equipment, Contractor shall provide and install
                mechanical constraints on all applicable equipment.
        2.8.    Each time a voltage measurement is made, Contractor's grounding personnel shall
                record the location, time, date, and pipe-to-ground potential. Contractor's grounding
                personnel shall measure pipe-to-ground voltages on all pipe sections at the following
                   Each day prior to construction activity and immediately following construction end of
                   Prior to any activity involving pipe contact work
                   As directed by the Company Representative
        2.9.    When a pipe-to-ground AC voltage exceeds 15 volts RMS, and before performing further
                work on the identified section of the project, Contractor shall render the pipe safe for
                human contact by grounding and/or attaching equipotential grids, as approved by
                Company Representative.
        2.10.   Contractor shall supply all required materials and shall fabricate circumferential pipe
                clamps in conformance with Company Construction drawings.
        2.11.   Ground rods shall be 3/4-inch diameter by 8 feet long zinc galvanized steel. Ground rod
                clamps shall be ‘Burndy #GAR-6426’ or equivalent. Grounding cable for temporary
                grounds and bonding shall be AWG #2 -1665 strand copper, neoprene-insulated welding
                cable. Grounding cable for permanent ground shall be AWG #6 -7 strand copper green
                USE-2. Connectors for connecting grounding cables to circumferential clamps or ground
                mats shall be ‘Burndy YA2C-L4’ or equivalent. Tower legs, unless approved by
                Company, shall not be used as grounding connections.
        2.12.   When installing pipe parallel to, or crossing, a power line ROW, Contractor shall
                permanently remove any electric utility counterpoise a minimum of 25 feet from the pipe.
                When installing parallel pipe in the power line ROW, Contractor shall remove electric
                utility counterpoise by cutting out a section of the counterpoise at each tower footing.
                Contractor’s location and removal of counterpoise shall be under the direction of the
                Company Representative and the electric power owner/utility.
        2.13.   Traffic within power line ROW corridor shall be minimized. All authorized rubber-tired
                vehicles operating within power line ROW shall be grounded to mitigate capacitive
                coupling with the power line. Contractor shall ground vehicles by attaching conductive
                chain to the vehicle frame (to maintain contact with the ground). Rubber-tired vehicles
                shall not be refueled within 300 feet of an electric power line ROW unless all involved
                vehicles are electrically bonded prior to refueling.
        2.14.   To mitigate any capacitance coupling or induced voltage from nearby power lines, all pipe
                strung along the ROW shall be grounded. In addition, all metal-construction sheds,
                trailers, fences, or equipment (subject to AC influence) shall be grounded. Pipe shall be
                grounded at a frequency necessary to maintain an AC voltage level of less than 15 volts
                (RMS) at no less than 1,000-foot intervals with the first ground at the beginning of the
                section. Ground connections shall be made using materials and procedures specified
        2.15.   Where an AC voltage level of less than 15 volts (RMS) cannot be achieved through
                grounding, Contractor shall use additional precautions, including grounding mats or other
                provisions as determined by the electrical safety crew and Company Representative (to
                protect personnel and/or equipment).

Highlighting indicates revisions made as of the date on this standard.                        Page 2 of 3
                                                 Section:      C1280
                                                 Title:        Mitigating Induced AC Voltage during
CONSTRUCTION STANDARDS                           Revised:      7-1-2005

        2.16.   For lowering-in, coated pipeline shall be handled with non-conductive slings for lifting and
                non-conductive rope for guiding. Contact with the bare portion of the pipeline shall be
                avoided when removing support slings from pipeline ends (as the coated pipeline may
                not be effectively grounded during part of this operation).

Highlighting indicates revisions made as of the date on this standard.                          Page 3 of 3

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