511 EM 385-1-1 Chapters 9-15

Sections

11-8. General Requirements.

Grounding and Bonding Instructions

Ground and bond all electrical circuits, equipment, and enclosures as per the standards of 29 CFR 1910.304, NFPA 70, and NESC.
Ensure that portable and vehicle-mounted generators comply with grounding and bonding requirements, including the use of GFCI protection and proper bonding of the neutral to the frame.
Ground and bond portable and semi-portable electric tools and equipment, and ensure that double-insulated tools are distinctly marked and listed by a NRTL.

Temporary Structures, Equipment, and Fencing Grounding and Bonding

Bond all metal piping systems on temporary structures or equipment with electrical power and services attached as per NFPA 70 Article 250 bonding requirements.
Bond and ground temporary buildings, structures, or fencing near overhead electrical power transmission and distribution lines under specific conditions.
Connect temporary structures near substations and power generation facilities to the facility ground grid mat and bond all metallic components together.

Grounding Electrode and System Ground Connections

Use IEEE 837 rated equipment for system grounding above 1000V and UL 467 listed equipment for less than 1000V.
Ensure proper grounding and bonding of all equipment before energization and do not use designated grounding conductors as current-carrying conductors.
Equip temporary bonding or grounding with sufficient size and secure attachments to create an equipotential zone.

GFCI Protection and Temporary Protective Ground (TPG)

Provide GFCI protection for all receptacle outlets used in temporary electrical power and ensure testing and proper installation as per NFPA 70.
Place TPGs according to OSHA, NFPA 70E, and NESC requirements, considering specific conditions and ensuring employee protection from hazardous electric potential.
Use TPG equipment capable of conducting maximum fault current and test it according to the respective standards.

Temporary Wiring and Lighting

Submit a sketch of the temporary power distribution systems for approval, including location, voltages, and protection means.
Perform testing of temporary electrical distribution systems for polarity, ground continuity, and resistance, and ensure GFCIs are tested regularly.
Provide adequate vertical clearance for temporary wiring and ensure proper design and installation in wet locations as per manufacturer's instructions and safety standards.

Additional Instructions for Temporary Lighting and Portable Hand Lamps

Provide temporary lighting as per chapter 7 and protect all lamps for general illumination from accidental contact or breakage.
Equip portable hand lamps with insulating material handles, substantial guards over bulbs, and ensure grounding of metallic guards.
When temporary wiring is used in confined spaces, provide an approved disconnect near the entrance for emergency power disconnection.

11-9. Figures and Tables.

See Figures/Tables Checklists/Forms

11-10. Checklists and Forms.

See Figures/Tables Checklists/Forms

Knowledge Check Choose the best answer for the question.

11-12. Provide GFCI protection for all receptacle outlets used in _____.

bonding metal piping systems

temporary electrical power

grounding temporary buildings

bonding metallic components together

You forgot to answer the question!

EM 385-1-1 Paragraph 11-8 (l.–m.).

11-8. General Requirements (l.–m.).

l.  Grounding and Bonding.  Unless otherwise noted in this manual, provide a permanent, continuous, and effective path to ground by grounding and bonding all electrical circuits, equipment, and enclosures according to 29 CFR 1910.304, NFPA 70, and NESC as applicable to the installation.  (11-8.l)

(1) Generators.

(a)  Portable Generators.  The frame of a portable generator is not required to be grounded and may serve as the grounding electrode for a system supplied by the generator if the generator supplies only equipment mounted on the generator and/or cord-and-plug-connected equipment through receptacles mounted on the generator, and the non-current-carrying metal parts of the equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.
        (b)  Mobile/Vehicle-Mounted Generators.  The frame of a vehicle is not required to be grounded and may serve as the grounding electrode for a system supplied by a generator located on the vehicle under the following conditions:

(b-1)  The frame of the generator is bonded to the vehicle frame.

(b-2)  The generator supplies only equipment located on the vehicle or cord-and- plug- connected equipment through receptacles mounted on the vehicle.

(b-3)  The non-current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.

(b-4)  The system complies with provisions of 29 CFR 1910.304.

(c)  Portable and vehicle mounted generators used for construction activities must have GFCI protection. The neutral must be bonded to the frame of the generator and/or vehicle (see NFPA 70 445.20(B) and 590.6(A)(3)).  Portable GFCIs are allowed for use with generators manufactured or remanufactured prior to January 1, 2011, when used according to paragraphs 11-8.l(1)(a) and (b) of this chapter.

Note.  USACE does not recognize the exception in 29 CFR 1926.404(b)(1)(ii) that states “Receptacles on a two-wire, single-phase portable or vehicle-mounted generator rated not more than 5kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces, need not be protected with ground-fault circuit interrupters” since it conflicts with current NFPA 70 590.6(A)(3), UL-1248, UL-2201, and was removed from 29 CFR 1910.304(b)(4)(ii)(A) in 2007.

(d)  Portable generator installation is allowed as a temporary backup generator in a ‘floated neutral’ configuration (see NFPA 70).  The temporary backup generator must not operate as a separately derived system and must be connected to a transfer switch that bonds the floated neutral to the utility neutral.

(e)  The manufacturer must mark the generator indicating if the neutral or grounded conductor is bonded to the frame of the generator.  Remark the generator upon field modification of this bonding.

(f)  A system conductor (neutral or grounded conductor) that is required to be grounded according to NFPA 70 or 29 CFR 1910.304 must be bonded to the generator frame where the generator is a component of a separately derived system.

(g)  For OCONUS portable and vehicle mounted generators that have varying standards differing from this manual, refer to the host nation codes for grounding and bonding of these types of generators.

(2)  Portable and semi-portable electric tools and equipment must be grounded by a multi- conductor cord having an identified grounding conductor and a multi-contact polarized plug and receptacle.

(3)  Portable and semi-portable electric tools protected by an approved system of double insulation, or equivalent, do not need to be grounded.  Double-insulated tools must be distinctly marked and listed by a NRTL.

(4)  Ground all floodlights, light plants, and work lights unless they are marked by the manufacturer as double-insulated.

(5)  Do not use a grounding terminal or grounding-type device on a receptacle, cord connector, or attachment plug for purposes other than grounding.

(6)  Temporary Structures, Equipment, and Fencing.  Temporary structures, equipment, and fencing must comply with NFPA 70 Article 545, Relocatable Structure and Article 590, Temporary Installations in addition to the following:

(a)  Bond all metal piping systems on portable or temporary structures or equipment with electrical power supplied and water and sewer services attached according to NFPA 70 Article 250 boding requirements.

(b)  Where temporary buildings or structures are placed or constructed under or near overhead electrical power transmission and distribution lines, bond the metallic components on each building or structure together and ground them to earth when any of the following conditions exist:

(b-1)  The building or structure is within 100 feet (30.5 m) horizontally of the outside overhead wire.

(b-2)  The building or structure has more than 2,000 ft2 (185 m2) of metal surface and is located within 100 to 150 feet (30.5 to 45.7 m) horizontally of the outside overhead wire.

(b-3)  The building or structure is used to store flammable materials and is within 250 feet (76.2 m) horizontally of the of the outside overhead wire.

(c)  Connect temporary buildings, structures, or fencing located near substations and power generation facilities to the facility ground grid mat with engineered products and cables. Consult the facility owners for proper grounding procedures.  Near is defined in paragraphs 11-8.l(6)(b) and 11-8.l(6)(d) as applicable.  All metallic components on each building or structure should be bonded together by construction of the building or by addition of bonding jumpers. See paragraph 11-8.l(6)(d) below for fencing bonding.

(d)  When temporary metallic or electrically conductive fencing is placed or constructed under or near overhead electrical power transmission and distribution lines, each wire or woven mesh of wires must be bonded together and ground to earth if any of the following conditions exist:

(d-1)  It is in the right-of-way of the power lines.

(d-2)  It parallels the line within 125 feet (38.1 m) horizontally of the outside overhead wire and is longer than 150 feet (45.7 m).

(d-3)  It parallels the line 125 to 250 feet (38.1 to 45.7 m) horizontally from the outside overhead wire and is longer than 6,000 feet (1,829 m).

(7)  Grounding Electrode and System Ground Connections.

(a)  For 1000V and above (phase to phase) system grounding, use IEEE 837 rated equipment.

(b)  For less than 1000V (phase to phase) system grounding, use UL 467 listed equipment.

(c)  For all buried or encased grounding, when connecting a system ground grid to grounding buses and terminals, use IEEE 837 rated equipment.

(d)  Before energizing electrical systems, properly ground and bond all equipment to the appropriate code. Do not break bonding and grounding connections until systems are deenergized.

(e)  Do not use a designated grounding conductor as a current carrying conductor.

(8)  Conductors used for temporary bonding or grounding stationary and movable equipment must be of ample size to create an equipotential zone.

(a)  When attaching bonding and grounding clamps or clips, a secure and positive metal-to- metal contact must be made.

(b)  Attach the ground end first, then the equipment end. Attach or remove the equipment using insulated tools or other suitable devices.  When grounding and bonding equipment that contains flammable liquids, reverse this process (that is, attach the equipment end first then ground) to minimize the possibility of sparks near the flammable liquid.

(c)  When removing grounds, remove the line or equipment end first using insulated tools or other suitable devices.  When removing grounds from equipment with flammable liquids, reverse this process to minimize the possibility of sparks near the flammable liquid.

(9)  GFCI Protection for Personnel.  All receptacle outlets (125-volt, 15-, 20-, 30- amperage and greater) that provide temporary electrical power during construction, remodeling, maintenance, repair, or demolition must GFCI protection for personnel.

(a)  GFCI protection must be provided on all circuits serving portable electric hand tools or semi-portable electric power tools (for example, block/brick says, table saws, air compressors, welding machines, and drill presses).

(b)  GFCI devices used in general construction and for permanent installations must be UL 943 class A rated.  Special purpose GFCI devices are allowed under engineering supervision and must be UL 943C class C, D, or E rated.  GFCI devices must be tested before initial use and before use after modification.

(c)  In lieu of the requirement to install individual circuit protection, temporary power feeders are permitted to be protected by a ground fault protection equipment (GFPE) or RCD installed in a readily accessible location (see NFPA 70).

(d)  Protect receptable outlets that are not part of the permanent wiring of the building or structure with GFCIs using a receptacle outlet with integral GFCI protection, a standard receptacle outlet connected downstream of a receptacle outlet with integral GFCI protection, or receptacles protected by a GFCI-type circuit breaker.

(e)  Receptacle outlets that are part of the permanent wiring of the building or structure and are used for temporary electric power, (including portable generators) must use a portable GFCI if the receptacle outlets are not already GFCI protected.  The portable GFCI will be as near as practicable to the receptacle outlet.

Note. Exception: In industrial facilities where conditions of maintenance and supervision ensure that only QPs are involved, an AEGCP (see para 11-7.b) is permitted for only those receptacle outlets used to supply equipment that would create a greater hazard if power was interrupted or if their design is not compatible with GFCI protection.

(f)  Protect electric tool circuits that are hard-wired directly to an electrical source of power by a GFCI-type circuit breaker.

(g)  Install GFCIs according to NFPA 70.  Ground electrical circuits of permanent wiring according to NFPA 70.

(h)  GFCIs may be sensitive to some equipment (for example, concrete vibrators) or unavailable for the voltage and current rating, or a GFPE/RCD cannot be used.  In these instances, an AEGCP is acceptable in lieu of GFCIs provided it meets the requirements of paragraph 11-7.b.

(10)  Temporary Protective Ground (TPG).  Place and remove TPGs when grounding lines and equipment is required according to this chapter and OSHA, NFPA
    70E, and NESC requirements.

(a)  All de-energized conductors and equipment must be tested by a QP using a properly selected voltage meter or detector rated and designed for the system to be measured prior to the application of TPGs.

(b)  Place TPGs between the work location and all sources of energy as close as practicable to the work location in such a manner that the employer can demonstrate employees will not be exposed to hazardous differences in electric potential.

(b-1)  If work is to be performed at more than one location in a line section, ground and short circuit one location along the line section and ground the conductor to be worked on at each work location.  Bracket grounding must be performed under engineering supervision using calculations according to IEEE 1048 and IEEE 1246.

(b-2)  Maintain the applicable MAD in table 11-3 from ungrounded conductors at the work location.

(b-3)  Where the making of a TPG is impractical, or the conditions resulting from it would be more hazardous than working on the lines or equipment without grounding, the grounds may be omitted and the line or equipment worked as energized.

(c)  Grounds may be temporarily removed only when necessary for test purposes. Use extreme caution during the test procedures.  Consider all lines or equipment from which grounds have been removed to be energized.

(d)  When TPG electrodes are used (for example, for protective grounding during crane operations beneath an energized transmission line), such electrodes must have a resistance to ground low enough to provide protection from the anticipated system fault current. All work must be performed under engineering supervision using calculations according to IEEE 80, IEEE 1048, and IEEE 1246.

(e)  TPGs connected to a tower must be made with a tower clamp capable of conducting the expected fault current.

(f)  All TPG equipment must meet the following:

(f-1)  Equipment must be capable of conducting the maximum fault current that could flow at the point of grounding for the time necessary to clear the fault.

(f-2)  Equipment must have an ampacity greater than or equal to that of #2 AWG
            copper.

(f-3)  Equipment must have an impedance low enough so that it does not delay the operation of protective devices in case of accidental energizing of the lines or equipment.

(f-4)  Equipment must be tested using the listing agency’s recommended testing frequencies and procedures.  ASTM listed cable sets must be tested according to ASTM F2249 standards.  IEC listed cable sets must be tested using IEC standards.

Note. ASTM F855 is an example of a standard that meets these requirements.  If another testing standard is used, it must be evaluated by engineering and the AHJ to determine these requirements are met.

m.  Temporary Wiring and Lighting.  (11-8.m)

(1)  A sketch of proposed temporary power distribution systems must be submitted to the USACE supervisor for approval or acceptance by the KO or COR for use before temporary power is installed.  The sketch must show the location, voltages, and means of protection of all circuits (that is, receptacles, disconnecting means, grounding, GFCIs, and lighting circuits).  Include the accepted sketch in the AHA associated with the temporary system.  (See para 11-6)

(2)  Testing. Check all temporary electrical distribution systems and devices for acceptable polarity, ground continuity, and ground resistance before initial use and before use after modification. GFCIs must be tested monthly.  Portable type GFCIs must be tested for designed functionality before each use.

(3)  Measure ground resistance and circuits at the time of installation for compliance with paragraph 11-8.l(7).  Record the measurement and provide a copy to the USACE supervisor/KO or COR.

(4)  Provide vertical clearance of temporary wiring for circuits carrying 600V or less:

(a)  10 feet (3 m) above finished grade, sidewalks, or from any platform.

(b)  12 feet (3.7 m) over areas, other than public streets, alleys, roads, and driveways, that are subject to vehicular traffic other than truck traffic.

(c)  15 feet (4.5 m) over areas, other than public streets, alleys, roads, and driveways, that are subject to truck traffic.

(d)  18 feet (5.5 m) over public streets, alleys, roads, and driveways.

(5)  Provide vertical clearance of temporary wiring for circuits carrying more than 600V according to NESC.

(6)  Wet Locations.

(a)  Only use submersible electric pumps in wet locations when the pump is designed by the manufacturer for such purpose.

(a-1)  A QP must install and test each pump.

(a-2)  Employees must be trained to operate pumps according to the manufacturer’s instructions.

(a-3)  When personnel are or could be present in the water during pump operation, the pump must be equipped with a UL 943 class A GFCI.  UL 943C class C, D, and E rated special- purpose GFCI devices, used for pump operation, are allowed under engineering supervision.

(a-4)  If pump manufacturer does not allow personnel in the area when pumps are used in water, an appropriate Hazardous Energy Control Program (HECP), to include LOTO, must be in place (see chapter 12).

(b)  Where a receptacle is used in a wet location, contain it in an enclosure that is weatherproof whether or not an attachment plug is inserted.

(c)  All temporary lighting strings in outdoor or wet locations (for example, tunnels, culverts, valve pits, floating plant) must consist of lamp sockets and connection plugs permanently molded to the hard service cord insulation.

(d)  Wires must be insulated from their supports.

(7)  Temporary Lighting.

(a)  Illumination.  Provide temporary lighting according to chapter 7. Construction areas, ramps, runways, corridors, offices, shops, and storage areas must be lighted to not less than the minimum illumination intensities listed in 29 CFR 1926.56(a), table D-3 while any work is in progress.

(b)  Protect all lamps for general illumination from accidental contact or breakage. Ground all metal-case sockets.

(c)  Do not suspend temporary lights by their electric cords unless cords and lights are designed for this means of suspension.

(d)  Immediately replace exposed empty light sockets and broken bulbs.

(e)  Portable electric lighting used in wet and/or other conductive locations (for example, drums, tanks, vessels, sumps, scroll cases) must be rated and operated at 12 volts or less. 120- volt lights may be used if protected by a GFCI.  (See para 11-8.l(9))

(8)  Portable Hand Lamps.  Portable hand lamps must be wired with flexible cord and a polarized or grounding type attachment plug.  If the portable lamp uses an Edison-based lamp holder, the grounded conductor must be identified and attached to the screw shell and the identified blade of the attachment plug.  In addition, portable handlamps must comply with the following:

(a)  Equip hand lamps with a handle of molded composition or other insulating material.

(b)  Do not use metal-shell, paper-lined lamp holders.

(c)  Hand lamps must be equipped with a handle and a substantial guard over the bulb.  The guard must be attached to the lamp holder or the handle.

(d)  Ground metallic guards by means of an equipment grounding conductor run within the power supply cord.

(9)  When temporary wiring is used in tanks or other confined spaces, provide an approved disconnect that is properly identified, NRTL labeled, and rated for this application and environment at or near the entrance to such spaces, for the purpose of readily disconnecting the electrical power in case of an emergency.

(10) If type nonmetallic sheathed, nonmetallic sheathed corrosion resistant, and service entrance (SE) cables are used in temporary installations, they must meet NFPA 70 requirements, including the following:

(a)  Install along studs, joists, or similar supports while closely following the building finish or running boards.

(b)  Attach firmly to each cabinet, box fitting, or fixture by means of a cable clamp. Do not use non-metallic sheathed cables as portable extension cords, where subject to frequent flexing, or as a SE cable and do not lay them on the ground subject to any type of traffic.

(c)  Keep temporary lighting circuits separate from electric tool circuits. Receptacle circuits must be dedicated to either temporary lighting or electric tools and must be labeled "LIGHTS ONLY" or "TOOLS ONLY," as applicable.