Chapter 8
ELECTRICAL SAFETY

Contents

Approved by Keith Gershon
Revised 12/08


NOTE:
  Denotes a new section.
Denotes the beginning of changed text within a section.
Denotes the end of changed text within a section.

8.1 Introduction

In the United States, 4,000 non-disabling and 3,600 disabling electrical contact injuries occur in the workplace annually. 2,000 workers are sent to burn centers with electric burns each year. Most of the burn victims become permanently disabled from their injuries. Typically, the victim’s lives are forever restricted due to sensitivity to cold weather, mobility, or other physical barriers. Every day one person dies from electrical incidents.

This chapter contains general requirements and information for all electrical work at LBNL. All employees of the lab, participating guests, students and all subcontractors working at the lab must comply with the requirements in this chapter.

8.2 Definitions and Acronyms

Definitions of terms used in this chapter are included as Appendix D. Many terms used in this Chapter have meanings unique to electrical safety. All such terms will be printed in small capitols. Acronyms used are as follows:

8.3 Scope

The purpose of this chapter is to ensure the electrical safety of every employee, visiting guest and subcontractor at the lab by:

  1. Defining safe work practices and use requirements for all people who work with electrically energized equipment as part of their normal job duties.
  2. Establishing training requirements for qualifying and authorizing LBNL employees who work on or near energized electrical circuits and components.
  3. Establishing a process for evaluating the electrical hazards of every energized electrical work task and for providing commensurate hazard controls.
  4. Establishing a formal process for controlling energized electrical work through an approval process.
This Chapter applies to:

Reading this chapter does not qualify the reader to perform electrical work. Guidelines that are beyond the scope of this document must be established at each work area. They should include, as a minimum, the safety concerns outlined herein.

This chapter is in no way to be construed as a synopsis of all electrical requirements, nor as a substitute for formal study, training, and experience in electrical design, construction, and maintenance.

8.4 Policy

It is the policy of LBNL that:

  1. LBNL shall comply with DOE and OSHA regulations, NFPA 70, National Electrical Code, NFPA 70E, Standard for Electrical Safety in the Workplace, ANSI C2, National Electrical Safety Code (NESC), and other established safety standards to reduce or eliminate the dangers associated with the use of electrical energy.
  2. All electrically energized equipment will be used in a safe manner as intended by the manufacturer and the NRTL listing or AHJ acceptance criteria.
  3. All electrical wiring and equipment installations will comply with the National Electrical Code, OSHA regulations, and other consensus industry standards for electrical safety and engineering.
  4. All employees have a responsibility to ensure they and others around them are working in a safe manner with the proper equipment and hazard controls. LBNL has a Stop Work Policy, (PUB 3000, Chapter 1.5) It is the responsibility of everyone to exercise this policy when observing unsafe work conditions or practices.
  5. All research or test devices operating at a voltage greater than 50 volts with the ability to produce 5mA or more of current, or having capacitors greater than 1J (joules), or 1000 Joules if less than 50 volts, must be protected by an enclosure with secured or interlocked covers, or isolated in a manner that will prevent inadvertent contact with exposed live parts.
  6. Fabrication of research and test equipment will be done following prescribed LBNL design and engineering requirements.
  7. Any potentially electrically hazardous work will be performed following Lockout Tagout rules as described in PUB 3000, Ch. 18.
  8. Work will only be performed on electrically-hazardous electrical circuits or components when it can be demonstrated that de-energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Energized parts not considered electrically-hazardous shall not be required to be deenergized if there will be no increased exposure to electrical burns or to explosion blast due to electric arcs. Approval is required per Section 8.7.1 before approaching nearer than the limited approach boundary or arc flash protection boundary.
  9. When work on electrically-hazardous electrical circuits or components s is justified and approved, controls (guards, covers, shields, insulated tools & probes, remote methods) must be used to reduce the potential for contact with energized components.
  10. All employees who work within the limited approach boundary or arc flash protection boundary of electrically-hazardous electrical circuits or components must be qualified and authorized by a JHA, AHD (See PUB3000, Chapter 6) or Subcontractor Electrical Safety Workbook (See Appendix B) prior to performing such work.
  11. Safety related work practices and procedures for employees who work within the limited approach boundary or arc flash protection boundary of electrically-hazardous electrical circuits or components will be done in accordance with the requirements of NFPA 70E, Standard for Electrical Safety in the Workplace.
  12. Subcontract employers will ensure their employees comply with NFPA 70 and NFPA 70E when their work is covered by the respective code or standard. LBNL points-of-contact for the contract will inform the contract employer of any additional information needed by the contract employer to perform an adequate electrical hazard analysis for their employees and ensure a Subcontractor Electrical Safety Workbook and if necessary, an Energized Electrical Work Permit (EEWP) is completed.

8.5 Electrical Hazards

8.5.1 Electrical Shock

Accidental contact with exposed electrical parts operating a voltage greater than 50 volts to ground and having a current greater than 5 milliamperes can cause serious injury or death. Fatal ventricular fibrillation of the heart can be triggered by a current flow of as little as several milliamperes. Severe injuries, such as deep internal burns, can occur even if the current does not pass through the vital organs or nerves.

8.5.2 Delayed Effects

Damage to the internal tissues may not be apparent immediately after contact with the current. Delayed internal tissue swelling and irritation are possible. Prompt medical attention can help minimize these effects and avoid death or long-term injury.

8.5.3 Arc Flash

When an electric current passes through the air between two conductors, the temperature can reach 35,000°F. Exposure to these extreme temperatures can result in life threatening burns. The majority of hospital admissions due to electrical accidents to qualified workers are from arc-flash burns, not electrical shocks. Arc-flashes can and do kill at distances in excess of 10 ft. Equipment that presents an arc flash hazard must be marked with a label describing the available incident energy and level of PPE required for work within the arc flash boundary when the equipment is energized.

8.5.4 Arc Blast

The tremendous temperatures of the arc cause an explosive expansion of both metal and the surrounding air in the arc path. For example, copper expands by a factor of 67,000 times when changed from a solid into a vapor. The dangers of this explosion are of high blast pressure wave, high decibel levels of sound and high velocity shrapnel. Finally the material and molten metal is expelled away from the arc at speeds exceeding 700 miles per hour. Arc blasts often cause severe injuries and death.

8.5.5 Other Burns

Other burns suffered in electrical accidents are of two basic types: electrical burns and thermal contact burns. In electrical burns, tissue damage (whether skin deep or deeper) occurs because the body is unable to dissipate the heat caused by the current flow. Typically, electrical burns are slow to heal. Thermal contact burns are those normally experienced from skin contact with the hot surfaces of overheated electric conductors.

8.6 Hazard Controls When Performing Electrical Work

The following hazard control hierarchy will be used to mitigate electrical hazards before approaching within the limited approach boundary or arc Flash protection boundary of energized electrical conductors or circuit parts:

  1. Placing the electrically-hazardous conductors or circuit parts into an electrically safe work condition (see PUB 3000, Chapter 18, Lockout/Tagout).
  2. Applying supplemental physical controls, such as panels, shields or barriers, to isolate employees from the energized components.
  3. Administrative controls, such as the Energized Electrical Work Permit, assignment of a Safety Watch, and qualification training.
  4. Personal protective equipment (PPE) to isolate workers from exposed hazardous electrical conductors or circuit parts.
  5. Safe work practices (safe work rules & electrical safety considerations) to support the development of safe working habits.

8.6.1 Establishing an Electrically Safe Work Condition

Electrically-hazardous conductors or circuit parts are considered safe when the practices described in PUB-3000, Chapter 18, have been applied and verified using the following procedure:

  1. Determine all possible sources of electrical supply to the specific equipment.
  2. After properly interrupting the load current, open the disconnecting device(s) for each source.
  3. Wherever possible, visually verify that all blades of the disconnecting devices are fully open.
  4. Apply lockout/tagout devices in accordance with PUB3000, Chapter 18.
  5. Use an appropriately rated voltage detector to test each phase conductor or circuit part both phase to phase and phase to ground to verify they are deenergized.
  6. Where the possibility of induced or stored electrical energy exists, apply grounding devices.

8.6.2 Supplemental Physical Controls and Administrative Controls

Where it is infeasible or where a greater hazard would be introduced by de-energizing electrically-hazardous conductors or circuit parts, additional physical and administrative measures to protect the worker shall be incorporated into the work process. Examples to be considered include (but are not limited to):

8.6.3 Personal Protective Equipment (PPE)

Qualified workers who are potentially exposed to electrical hazards that cannot be controlled through some engineering means must be provided with and use personal protective equipment that is appropriate for the specific work to be performed and the associated hazard level. NFPA 70E defines PPE requirements PPE is required for any work within the restricted approach boundary or arc flash protection boundary.

8.6.4 Safe Work Rules

Note: A summary of the LBNL electrical safe work rules is provided below. For a more thorough description of the safe work rules see Appendix M.

  1. Positively ensure the correct circuit is identified before lockout and tagout.
  2. Whenever possible deenergize the equipment before testing.
  3. The employee in charge must conduct a briefing before all energized electrical work.
  4. Identify hazards and anticipate problems.
  5. Resist “hurry-up” pressure.
  6. Don’t hesitate to use the Stop Work Policy (PUB 3000, Chapter 1.5).
  7. Always consider electrical equipment energized until positively proven otherwise.
  8. Use suitably rated electrical devices only as intended.
  9. Remove all conductive jewelry before performing energized electrical work.
  10. Know how to shut down equipment in an emergency.
  11. Know LBNL emergency procedures.
  12. Design for safety.
  13. Reset circuit breakers only after the trip problem has been corrected.
  14. Maintain the protection of covers, barriers and shielding.
  15. Never drill into a wall or floor slab without Facilities approval. See Admin 053 Facilities penetration Policy.
  16. Never modify or penetrate premises wiring conduit or enclosed wireways. Only qualified and authorized Facilities Department personnel are allowed to work on premises wiring, conduits or enclosed wiring. See Section 8.8.4.

Note: For a listing and description of other electrical safety considerations, see Section 8.13.

8.7 Energized Electrical Work Requirements

Energized electrical work is any activity inside the LIMITED APPROACH BOUNDARY or FLASH PROTECTION BOUNDARY of ELECTRICALLY-HAZARDOUS electrical conductors or circuit parts. Conductors or circuit parts are considered ELECTRICALLY-HAZARDOUS if they operate at a level that could cause injury to a worker through contact or exposure to an ARC FLASH HAZARD. Verification of absence of voltage for LOTO is considered to be energized electrical work. Authorization is required for all energized electrical work, but the method of authorization differs according to the task.

It is LBNL policy to deenergize electrically-hazardous parts, whenever possible, before an employee works on or near them (see PUB-3000, Chapter 18, Lockout/Tagout). This is the preferred method for protecting workers from electrical hazards. Workers are permitted to work on or near exposed energized electrical conductors or circuit parts only if it can be demonstrated that de-energizing would introduce additional or increased hazards or is infeasible due to equipment design or operational limitations. Energized parts that are not electrically-hazardous need not be deenergized if there will be no increased exposure to electrical burns or to explosion blast due to electric arcs.

8.7.1 Electrical Work Authorization

8.7.1.1 LBNL Employees

note: The requirement for an AHD for exposed electrical work is in a phase-in pilot program. Full implementation will become mandatory on June 1, 2009.

electrically hazardous testing, troubleshooting, and inspection activities are authorized by an Activity Hazard Document (AHD). Any work that is not specifically authorized in an AHD, requires an EEWP (Appendix A). The authorization will consider hazards for both contact and arc flash exposures.

Work requiring an EEWP shall have a task-specific electrical hazard analysis completed and documented on the EEWP. At a minimum, the hazard analysis must determine:

  1. The voltage of all exposed energized electrical components,
  2. The Shock Approach Boundaries from NFPA 70E that will be crossed,
  3. The shock-protection PPE that is necessary to prevent contact with energized components,
  4. The Arc Flash Protection Boundary,
  5. The PPE necessary within the Arc Flash Protection Boundary that will prevent injury should an arc flash occur.

Depending on the risk, complexity, or severity of the task, additional controls may be necessary. The worker performing the task shall be qualified to recognize and avoid any electrical hazards associated with the equipment or task. Controls may include the need for a safety watch or second person while the task is performed. For assistance in conducting an electrical hazard analysis, see Appendices A, B, C, O, and Q or contact either the Division Safety Coordinator or Electrical Safety AHJ.

8.7.1.2 Subcontractors

LBNL Subcontractors performing any exposed electrically hazardous work shall complete a Subcontractor Electrical Safety Workbook (Appendix B) and an EEWP (Appendix A)

8.7.2 Job Briefing

Before starting a task that might expose a worker to an electrical hazard, a person in charge shall brief the worker of the hazards involved, necessary PPE, work practices required, and other information necessary to minimize the possibility of an electrical injury. The extent of the briefing depends on the risk and complexity of the task. If the work is authorized under an AHD the briefing will usually consist of simple direction by the supervisor noting any unique hazards associated with the assignment.

Work authorized by an EEWP requires a more extensive briefing (See Appendix C for a Job Briefing Checklist that can be used as an aid). The training and qualification currency of the worker should be verified and any potential emergency response actions discussed. Work should be released only when the supervisors and all workers know the scope of the work, hazards associated with the work, appropriate controls to manage the identified hazards and all are confident that the work can be done safely.

8.8 Qualifying and Authorizing Personnel

Only those persons who are both qualified and authorized may install, fabricate, repair, test, calibrate, or modify electrical or electronics wiring, devices, systems, or equipment.

A qualified and authorized person is an individual formally recognized by Laboratory Management as:

A person can be considered qualified and authorized with respect to certain equipment and methods but not authorized for others.

8.8.1 General Guidelines for Qualification

Qualification for electrical or electronics work is determined by the employee’s Supervisor, and is based on a combination of LBNL classroom training (including required periodic retraining), formal electrical trade, military, college or other training, work experience, and on-the-job training. Formal training can be the completion of apprenticeship or comparable training. Experience may be a combination of, or include, formal technical related education courses, hand-on field or classroom lab work that may or may not result in licenses or certifications.

On-going electrical and electronics training must include an annual review of this Chapter and all Appendices pertinent to the employee’s work assignment, Chapter 18 Lockout/Tagout, annual update of the employee’s JHA and AHD(s) . For specific work requirements the supervisor may add classes to the employee’s training course list not required by the JHA, but deemed important by the supervisor.

8.8.2 General Guidelines For Authorization

Authorization to perform electrical or electronics work by an employee is determined by the employee’s Line Management and Supervision, and is based on the skills, knowledge, and ability of the employee to perform a specific task safely and correctly.

8.8.3 Specific Qualification And Authorization Criteria

8.8.3.1 On-The-Job Training

On-the-job training for specified equipment or classes of equipment must be documented to ensure that training is adequate and consistent for all employees with similar tasks. This documentation must be reviewed and approved by a person who is knowledgeable in safe electrical work practices, and is familiar with the hazards involved in the apparatus. This training shall cover:

8.8.3.2 Task Specific Training Criteria

Supervisors shall use the following guidelines to determine whether an individual is qualified to perform specific electrical work. Different subsets of these criteria shall be selected according to the exact nature of the task; however, some analysis must always be performed, no matter how minor the job. Tasks that are performed less often than once per year shall require retraining before the performance of the work practices involved.

The supervisor shall authorize the employee to perform the work task only if he/she is satisfied that all relevant criteria are met. If the supervisor cannot verify an employee's qualifications, assistance from the Engineering Division or EH&S Electrical Safety Engineer should be obtained. As a minimum, the documentation of an employee’s qualifications should consider:

If the individual will be permitted to work within the Limited Approach Boundary of exposed energized parts operating at 50 volts or more the individual shall at a minimum be additionally trained in all the following:

8.8.4 Electrical Distribution Systems (Premises Wiring)

Only qualified and authorized Facilities Department or approved subcontract personnel are allowed to perform electrical wiring or other work directly connected to any facility electrical distribution system (premises wiring as defined by the NEC). Premises wiring includes that portion of utilization equipment (see 8.8.5 below) that is permanently connected (hard-wired) to the facility electrical distribution system, viewed from the utilization equipment’s first disconnect (or circuit breaker) looking backward into the premises wiring.

Connection to and diagnosis and repair of, circuit breakers in building electrical panels may only be done by specified qualified electrical workers.

If there is a question about what differentiates a facility system versus utilization equipment, consult the Electrical Safety Engineer or Facilities Electrical Shop Supervision.

8.8.5 Research Apparatus (Utilization Equipment)

Only qualified persons may fabricate, modify, install or repair electronic or electrical equipment used at LBNL. Supervisors are responsible for ensuring that only qualified persons under their supervision are assigned to work on electronic or electrical equipment at LBNL. The supervisor shall ensure the qualifications of these employees are documented. Any Laboratory worker or researcher who performs any electrical work must complete the EHS course Basic Electrical Hazard Awareness (EHS 260) as a prerequisite to further specific qualifications.

8.8.6 Electrical Two-Person Rule

Certain work requires two qualified persons. This occurs when work is considered electrically hazardous, as established by the conditions in Appendix Q or by the work supervisor. When the "Two-Person Rule" is required, both workers must be present at the work site, and each worker must be aware of the other worker's tasks and must:


Note: Both workers may perform separate work tasks so long as safety is not compromised.

8.8.6.1 Exemption To Two qualified persons

Under limited conditions, the Electrical Two-Person Rule may allow for a second person that is not a qualified person. All of the remaining requirements of Section 8.8.6 apply, and in addition the following must be met:

  1. Management must approve this exemption.
  2. During the briefing process the qualified person will assess the qualifications of the second person to determine that the work may proceed safely.
  3. The second person must be First Aid and CPR trained.
  4. The second person may not enter the Limited Approach boundary or the flash protection boundary.
  5. The electrical disconnecting means must be located outside of the limited approach boundary and the flash protection boundary.
  6. The electrical disconnect must be located within 50 feet of the second person.
  7. The second person must be briefed in emergency procedures and the electrical work being performed.

Note: This exemption only applies to the Two Person Rule, and shall not be used when a Safety Watch is required.

8.8.7 Electrical Safety Watch

A Safety Watch is a more stringent hazard control measure than the Two-Person Rule and must be implemented when there are grave consequences from a failure to follow safe-work procedures. This occurs when work is considered high-hazard electrical work, as established by the conditions in Appendix Q or by the work supervisor. When a Safety Watch is required, the Safety Watch must be a qualified person who is responsible for monitoring the qualified person(s) doing the work. A Safety Watch must:

8.8.8 Service or Maintenance Contracts (Equipment Subcontractors)

Any subcontractor that will be performing work involving a potentially hazardous electrical exposure shall submit a Subcontractor Electrical Safety Workbook (Appendix B) for approval two weeks prior to beginning work at LBNL. In addition, the specific electrically exposed tasks shall be authorized with an EEWP.

8.9 Roles and Responsibilities

8.9.1 Authority Having Jurisdiction (AHJ)

ELECTRICAL SAFETY decisions are made by the Authority Having Jurisdiction (AHJ). NFPA 70 defines the AHJ as “an organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation or a procedure.” In an R&D environment, there are frequent situations where facilities, equipment and work practices are developed that are not adequately addressed by codes or standards and interpretations are necessary for work to proceed safely. DOE has granted electrical AHJ authority to the Laboratory Director, who has delegated this authority as follows:

Facilities and Premises Wiring
The AHJ responsibility for the infrastructure power distribution and premises wiring of the Laboratory is delegated to the Facilities Division Director. The AHJ for the facilities and premises wiring interprets the NEC (National Electrical Code, NFPA 70) and other codes and approves electrical construction, electrical installations, and installed facilities electrical equipment for Code compliance. The Facilities Division Director may appoint an appropriately qualified electrical engineer to execute this authority.

Research and Scientific Equipment
The Engineering Division Director is delegated the responsibility as AHJ to assure compliance with appropriate ELECTRICAL SAFETY requirements for the design, installation, maintenance, and repair of research and development (R&D) and scientific equipment and apparatus. The Engineering Division Director will appoint an Electrical Engineer, which will be delegated with this authority. The Engineering Director will apply criteria from ANSI, UL, NFPA and other standards as appropriate to establish the safety of equipment. LBNL specific criteria may also be developed based on established engineering principles.

Electrical Safety--Work Practices & Workplace Conditions
The Environment, Health and Safety Division Director is delegated the responsibility for assuring compliance with all ELECTRICAL SAFETY requirements that pertain to maintaining safe electrical work practices and workplace conditions and thereby for protecting Laboratory employees, contractors and subcontract personnel from injury or death as a result of electrical hazards.

The AHJ for ELECTRICAL SAFETY is the Electrical Safety Engineer in the EH&S Division, or a qualified alternate designated by EH&S Management. The AHJ for ELECTRICAL SAFETY provides interpretations to ELECTRICAL SAFETY requirements in 29 CFR 1910 Subpart S and 29 CFR 1926 Subparts K and V, NFPA 70E, “Standard for Electrical Safety in the Workplace,” and other standards and codes for worker electrical safety. The AHJ for Electrical Safety will additionally apply the requirements of NFPA 70 in evaluating workplace conditions. The AHJ for Electrical Safety is responsible for coordinating the electrical equipment acceptance process.

8.9.2 Appeals

All appeals regarding electrical and electrical safety questions must be submitted to the SRC via the Electrical Safety Committee. These groups review the appeal and make recommendations to the Deputy Laboratory Director for Operations for a final decision.

8.9.3 Responsibilities

8.9.3.1 Individual Employees

Individual Employees are responsible for their own and their coworkers’ safety. Each employee will:

8.9.3.2 Supervisors

Supervisors of electrical workers have the primary responsibility of ensuring a safe working environment. They must;

8.9.3.3 Division Directors

Division Directors, by virtue of the delegation of responsibility for all aspects of occupational health and safety through line management, are responsible to the Laboratory Director for assuring compliance with all electrical safety requirements as defined in the procedure and pertaining to all programs, activities, and facilities within their respective divisions or areas of responsibility.

8.9.3.4 Facilities Division Director

The Facilities Division Director is responsible for interpretations of NFPA 70, The National Electrical Code. The Facilities Division Director will appoint a cognizant engineer, which will be delegated with this authority. This engineer will:

8.9.3.5 Engineering Division

The Engineering Division Director will nominate, from the Engineering Division, a chair for the Electrical Safety Committee. Engineering Division electrical engineers will:

8.9.3.6 Environment, Health and Safety Division Director

The Environment, Health and Safety Division Director is delegated the responsibility by the Deputy Laboratory Director for Operations for applying the Electrical Safety Program and assuring compliance with all electrical safety requirements that pertain to maintaining a safe working environment and protecting Laboratory employees and contract and subcontract personnel from injury or death as a result of electrical hazards.

The EH&S Division, is responsible for the documentation of Lab-wide electrical safety policies and procedures, site wide training, and field support for the implementation of the LBNL electrical safety program. EH&S will:

As the authorized representative of the EH&S Director, the Electrical Safety Engineer has the responsibility to ensure the acceptability of experimental electrical wiring and apparatus. In this capacity the Electrical Safety Engineer will:

8.9.3.7 Electrical Safety Committee

The Electrical Safety Committee (ESC) is a subcommittee of the LBNL Safety Review Committee (SRC). The Electrical Safety Committee has the responsibility to develop and maintain the LBNL Electrical Safety Program. The ESC will:

8.9.3.7.1 Composition

The ESC should be comprised of members who are knowledgeable in electrical safety, electrical systems, electrical equipment, and electrical requirements and standards (Fed OSHA, NFPA, NEC, and ANSI as appropriate).

8.10 Training

8.10.1 LBNL Training Courses

8.10.2 Training Matrix By Job Task

LOTO – EHS 256 NFPA 70E – EHS 267 or EHS 268 First Aid Safety – EHS 116 Adult CPR – EHS 123 Basic Electrical Safety- EHS 260 Qualified Electronic Techs – EHS 249 Qualified Electrician – EHS 250
Facilities Electricians X X X X     X
HVAC, Plant Maintenance Technicians & Lighting Technicians X X X X X    
Electronic Technicians X X X X   X  
Other General Lab Population performing authorized electrical work above 50V X X X X X    

8.11 Recordkeeping

8.12 Standards

8.13 Electrical Safety Considerations

8.13.1 General Considerations

GFCIs must be tested at least at 30-day intervals. Push the “test” button and observe if the “reset” button pops out and the receptacle turns off. Verify that the power is off by plugging in a small lamp or similar device. If this does not happen, the GFCI is not functional and must be replaced.

CAUTION: Testing of a GFCI will disconnect all receptacles protected by the GFCI. Before testing, determine which receptacles are protected. Verify that the interruption of power will not adversely affect other activities.

8.13.2 Clearance Around Electrical Equipment

Maintain access and working clearance space around power and lighting circuit breaker panels, motor controllers, and other electrical equipment in accordance with OSHA or the latest edition of the National Electrical Code (NEC), whichever is most stringent. For most equipment, this will be a space 30” wide by 36” deep.

Clearance space must not be used for storage or occupied by bookcases, desks, workbenches, or similar items. Not even a wastebasket.

8.13.3 Flexible Cords

Because cord and plug connections are generally well understood, this instruction does not cover portable hand-operated power tools, small kitchen appliances, office equipment, electronic instruments, personal computers, and other similar equipment.

Allowed Uses: Flexible cords and cables may be used for:

  1. Pendants.
  2. Wiring of fixtures.
  3. Connections of portable lamps or appliances.
  4. Elevator cables.
  5. Crane and hoist wiring.
  6. Connecting stationary equipment that requires frequent interchange.
  7. Preventing transmission of noise or vibration.
  8. An appliance or equipment with fastenings and mechanical connections specifically designed to permit removal for maintenance and repair, and intended or identified for flexible cord connection.
  9. Power cables (AC) for data-processing equipment.
  10. Connecting moving parts.

When flexible cords and cables are used in conditions 3, 6, or 8, above, they must be equipped with an approved attachment plug and energized from a receptacle outlet. Only qualified persons may install cord caps, (the attachment plug), on cords.

Flexible cord and cable, attachment plugs, and receptacles must be of the proper type, size, and voltage and current rating for the intended application.

Branch circuits that feed cord-and-plug connected equipment must be designed, have overcurrent protection and be grounded in accordance with the NEC.

All cord-and plug-connected equipment must be grounded with a correctly sized and identified equipment-grounding conductor that is an integral part of the ac power cord or cable. Exception: Listed equipment that is protected by a double insulation system or its equivalent.

Forbidden Uses of Flexible Cables:

  1. Substituted for the fixed wiring of a structure.
  2. Run through holes in walls, ceilings, or floors.
  3. Run through doorways, windows, or similar openings.
  4. Attached to building surfaces.
  5. Concealed behind building walls, ceilings, or floors.
  6. Installed in electrical raceways, unless specifically allowed by NEC provisions covering electrical raceways.

Except for the temporary wiring provisions of NEC, the NEC does not allow the cord-and-plug connection of equipment to be energized from extension cords. Extension cords are not legal substitutes for the fixed wiring of a structure such as a receptacle outlet.

In industrial locations, a suitable guard or cover must protect the interface between attachment plug and receptacle from intrusion of process waste or other foreign material, such as cutting oils and machining chips.

8.13.4 Extension Cords

Extension cords provide a convenient method of bringing ac power to a device that is not located near a power source. They are used as temporary power sources. Extension cords are probably involved in more electrical-code and safety violations than any other device at the Laboratory. They are stepped on, stretched, cut, overloaded, and, in general, used improperly.

Guidelines for the Safe Use of Extension Cords:


Avoiding Misuse of Extension Cords: Observe the following restrictions to avoid misuse of extension cords:

8.13.5 Relocatable Power Taps

A relocatable power tap (also referred to as a power strip) is a variation of an extension cord, where the cord terminates in a row or grouping of receptacles. Relocatable power taps are commonly used in offices to provide multiple receptacles to office equipment. In general, all rules pertaining to extension cords also apply to relocatable power taps.

Additional considerations are:

8.13.6 Heating Tapes and Cords

Many experiments at LBNL use heating tapes or cords, including many high vacuum apparatus. The heating tapes or cords pose an electrical shock hazard if not used properly. This advisory establishes requirements for the proper selection, care, and use of heating tapes and cords. These guidelines also apply to heating pads, wraps, or similar components intended to be applied directly to laboratory apparatus. Exemptions to the below requirements must be approved by the EH&S Electrical Safety Engineer.

This document supplements procedures and policies found in this PUB-3000 chapter (Chapter 8, Electrical Safety).

General Electrical Safety Requirements for Use of Heating Tape

Heating Tape Power Source Requirements

Unusual Conditions

  1. Circuit Breaker Trip
  1. GFCI Trip
  1. Variable Transformer Issues

For More Information please contact an LBNL qualified electrical worker, Facilities Electrical Shop staff (x6023), or the EH&S Electrical Safety Engineer (x4694) with any questions.

 

_____________________

<< Chapter 7 || Table of Contents || Appendix A >>