These guidelines have therefore been prepared to assist facilities in reviewing and developing programs relevant to electrical safety. It is recognized that these guidelines cross areas covered by several electrical safety references.
PURPOSE
These guidelines form a summary of good practices and describe the key elements of programs that support electrical safety at DOE facilities. These guidelines are written to assist facilities in meeting performance and safety objectives related to electrical hazard reduction.
SCOPE
It is expected that facilities may use different approaches or methods than those defined in the guidelines. References to NFPA 70E, Standard for Electrical Safety in the Workplace, are taken from the 2009 edition.
ELECTRICAL SAFETY PROGRAM
In other than the appendices of this document, "shall" refers to requirements of regulatory standards identified in the Code of Federal Regulations (CFR) in 10 CFR 851, Worker Health and Safety Program, which may or may not apply to a specific location (eg Southwestern Power Administration, Western Area Power Administration, Bonneville, etc.). In the case of a major renovation of an existing facility, the amendment 1.1 will comply with current standards.
AUTHORITY HAVING JURISDICTION
If the AHJ needs to address issues beyond its electrical expertise, such as fire, confined spaces, fall protection, and the like, the AHJ should consult with knowledgeable experts before making a decision. The AHJ may permit alternative methods if it is assured that equivalent objectives can be achieved through the establishment and maintenance of effective safety equal to or greater than established codes, regulations and standards.
GENERAL REQUIREMENTS 4
Work on Electrical Equipment
Considerations for Working on Energized Systems and Equipment
Other work, independent of voltage, which presents a significant shock, arc flash or arc flash hazard to workers2.9 should be analyzed and appropriate controls provided.
Safety Watch Responsibilities and Qualifications
BASIC SAFEGUARDS
RESPONSIBILITIES
Management Responsibilities
Employee Responsibilities
MODIFICATIONS TO FACILITIES
APPROVAL OF ELECTRICAL EQUIPMENT
CODES, STANDARDS, AND REGULATIONS
TRAINING AND QUALIFICATIONS OF QUALIFIED WORKERS
Formal Training and Qualifications
OSHA under 29 CFR 1910.269(a), Electric Power Generation, Transmission and Distribution and 1910.332, Electrical Training, also requires training for persons other than qualified workers if their work duties bring them within a safe distance of hazardous electrical energy. Supervisors of unqualified personnel should have at least the same level of electrical safety training if the work of those they supervise brings them close enough to exposed parts of electrical circuits that a hazard may occur.
Training of Safety Personnel
WORKING SPACE AROUND ELECTRICAL EQUIPMENT
Electrical Equipment Rated at 600 Volts or Less
There must be 2.21 space in the work area to allow opening of equipment doors or hinged panels at least 90 degrees to the service equipment. The depth of the working space should 2.18 be 3 feet, 3.5 feet, or 4 feet, depending on existing conditions.
Electrical Equipment Rated over 600 Volts
IDENTIFICATION OF DISCONNECTING MEANS
Disconnecting Means
Panelboard Circuit Directories
Enclosure Labeling
Load Labeling
Source Labeling
WORK INSTRUCTIONS
Safe Work Instructions and Supervision
Work Planning
ELECTRICAL PERSONAL PROTECTIVE EQUIPMENT
- Management's Responsibilities
- Inspecting PPE
- Cleaning and Electrical Testing of PPE
- Live-Line Tools
- Fiberglass-Handled Tools
- Maximum-Use Alternating Current (AC) Voltage
- Maximum Usage Voltage for Live-Line Tools
- Rubber-Insulated Gloves
- Storage
- Safety Shoes, Hardhats, and Glasses
The manufacturer's recommendations should be followed2.34 regarding the type of paint or ink to be used. Live tools must be cleaned and inspected before use and must undergo a dielectric test when their insulation value is suspect.
WORK PRACTICES
- Establishing an Electrically-Safe Work Condition
- Training
- Planning the Work
- Personal Protective Equipment
- Electrical Injuries
Relaxation procedures shall 2.45 be included in the lockout/shutdown procedure for the circuit or equipment to be de-energized. Circuits and equipment to be worked on must2.45 be disconnected from all sources of electrical energy.
Hazard Analysis 24
ELECTRICAL PREVENTIVE MAINTENANCE PROGRAM
MAINTENANCE
INSPECTION
ESSENTIAL ELEMENTS
PLANNING AND DEVELOPING AN EPM PROGRAM, AND FUNDAMENTALS OF EPM
GROUND FAULT PROTECTION AND ARC FAULT CIRCUIT INTERRUPTERS
Ground Fault Circuit Interrupters (GFCIs)
The fuse or circuit breaker only breaks or opens the circuit if a line-to-line or line-to-ground fault occurs that is greater than the rating of the circuit protective device. If any current flows into a fault, the sensing circuit opens the breaker and stops all current flow.
Arc Fault Circuit Interrupters (AFCIs)
As long as the current in both load wires remains within the specified tolerances, the circuit functions normally. Differential transformers continuously monitor circuits to ensure that all current flowing to the motor or devices returns to the source through the circuit conductors.
Ground Fault Protection for Equipment (GFPE)
OVERCURRENT PROTECTIVE DEVICES
GROUNDING 30
CIRCUIT AND SYSTEM GROUNDING
EQUIPMENT GROUNDING
BONDING
GROUNDED OR UNGROUNDED SYSTEMS
Grounded Systems
The EGC carries fault currents from the point of the fault to the grounded bus in the service equipment where it is transferred to the grounded conductor. The grounded conductor carries the fault current back to the source and returns across the faulted phase and opens the OCPD.
Ungrounded Systems
Note: Unearthed systems V AC,5.8 must be equipped with earth detectors and proper maintenance carried out to avoid, as far as is practicable, overcurrent from a persistent earth fault on unearthed systems. If adequate maintenance is not provided for ungrounded systems, a grounded system should be installed to ensure that ground faults are cleared and circuits, equipment and personnel are safe.
High-Impedance Grounding
GROUNDING REQUIREMENTS
GROUNDING ELECTRODE CONDUCTOR (GEC)
Sizing the Grounding Electrode Conductor
NEC 250.66 requires that the GEC be sized according to the mils rating of the largest service entrance conductor or conductors and selected from NEC Table 250.66 based on these values.
Exceptions to NEC 250.66
MAIN BONDING JUMPER
For phase conductors larger than 1100 KCmil copper or 1750 KCmil aluminum, the size of the main bonding jumper 5.18 should not be less than 12.5% of the largest phase conductor.
SYSTEM WITH GROUNDED CONDUCTOR
When the service entrance conductors are larger than 1100 KCmil copper or 1750 KCmil aluminum, the grounded conductor shall be 5.16 12.5% of the largest phase conductor. When the service phase conductors are in parallel, the size of the earthing conductor 5.23 shall be based on the total cross-sectional area of the phase conductors.
EQUIPMENT GROUNDING CONDUCTOR
Sizing the Equipment Grounding Conductor
Each parallel 5.27 EGC shall be sized based on the ampere rating of the overcurrent device protecting the circuit conductors. When conductors are sized to compensate for voltage drop, EGC 5.29 must also be sized.
Separate Equipment Grounding Conductors
When conductors are run in parallel in more than one raceway, the EGC is also run in parallel. However, it must 5.28 be dimensioned for the largest overcurrent unit that protects conductors in the raceway.
UNGROUNDED SYSTEMS
NEC 250.122 lists requirements for calculating the size of an EGC in an electrical circuit. If more than one circuit is installed in one guide tube, one EGC can be installed in the gear.
GROUNDING A SEPARATELY DERIVED SYSTEM
GROUNDING ELECTRODE SYSTEM
A bar #4 conductor at least 20 feet in length and near the bottom of the concrete foundation (within 2 inches), or ½ inch minimum reinforcing steel or bars at least 20 feet in length (a continuous length or spliced together using regular steel ties wires).5.42 4.
PERSONNEL PROTECTIVE GROUNDS
- Purpose of Personnel Protective Grounds
- Criteria for Personnel Protective Grounds
- Grounding Clamps
- Screw-Tightening Devices
- Grounding Cable Length
- Grounding Cable Connection
- Connecting Grounding Cables in Sequence
- Removing Protective Grounds
- Protective Apparel and Equipment
Ground cables must 5.52 be connected to the ground bus, structure or conductor first and then to the individual phase conductors. The ground cable conductors attached to the ground bus, structure or conductors must 5.53 always be removed last.
SPECIAL OCCUPANCIES 47
- Evacuation
- Shutdown of Operations
- Lightning Protection
- Static Electricity
- Electrical Equipment and Wiring
- Testing
The testing will only be performed with instruments specifically designed for soil-soil system testing. Public traffic route distance if loss of the line6.36 does not cause serious social or economic hardship.
PREVENTION OF EXTERNAL IGNITION AND EXPLOSION
- Sources of Ignition
- Combustion Principles
- Evaluation of Hazardous Areas
- Intrinsically Safe Equipment
- Enclosures
- Purging/Pressurization Systems
Threaded joints can be used as an escape route to cool the hot gases as they pass through the threads to the outside of the enclosure (Fig. 6-4). In Class II locations, the enclosure must keep dust out of the interior and operate at a safe surface temperature.
HAZARDOUS LOCATIONS
- Class I
- Class II
- Groups
- Ignition Temperature
- Flammable (Explosion) Limits
- Flashpoint
In which gases or vapors are normally prevented, by means of positive mechanical ventilation, from forming ignitable concentrations and which can become dangerous in the event of failure or abnormal operation of the ventilation equipment. or. The difficulty of manufacturing equipment and enclosures for use in a hydrogen atmosphere was also recognized, as was the cost of the equipment.
ELECTRICAL EQUIPMENT FOR CLASS I, II, AND III AREAS
Seals and Drains
Sealing accessories are listed by an NRTL for use in Class I hazardous locations with sealant only. Certain styles of sealing fittings are for use with vertical or near-vertical tubes in sizes from.
DESCRIPTIONS, FEATURES, AND TEST CRITERIA OF ENCLOSURES FOR HAZARDOUS
Type 7 Enclosures
Enclosed heat-generating devices shall6.65 not cause external surfaces to reach temperatures capable of igniting explosive gas-air mixtures in the surrounding atmosphere. Provide a hazardous gas environment with a degree of protection against an internal explosion or against the operation of internal equipment.
Type 8 Enclosures
The arc is confined below the oil so as not to ignite an explosive mixture of specified gases in the internal spaces above the oil or in the atmosphere surrounding the enclosure. Enclosed heat generating equipment shall not 6.66 cause external surfaces to reach temperatures capable of igniting explosive gas-air mixtures in the surrounding atmosphere.
Type 9 Enclosures
Do not develop surface temperatures that exceed prescribed limits for the specific gas corresponding to the atmosphere for which the enclosure is intended when internal equipment is at rated load. Withstand a series of operational design tests with oil levels arbitrarily lowered and with flammable gas-air mixtures introduced above the oil.
UNDERGROUND FACILITIES
- Work on Electrical Equipment and Circuits
- Power Cables and Conductors
- Trailing Cables
- Trolley Circuits for Track Haulage
Trolley wires and trolley feed wires must be overcurrent protected in accordance with the requirements of 30 CFR 57.12001 and 30 CFR 75.1001. Track that serves as a cart return circuit must be glued or welded in accordance with the requirements of 30 CFR 57.12042.
REQUIREMENTS FOR SPECIFIC EQUIPMENT 77
Electrical Design Criteria
CRANES AND HOISTS
- NEC General Requirements
- Disconnecting Means
- Grounding
- Control
- Clearances
- OSHA and NEC Requirements
- Maintenance and Operations
- Documented Maintenance
- Mechanical Elevating and Rotating Equipment
Equipment grounding conductors routed with circuit conductors shall 7.8 comply with Article 250 of the NEC. 7.14 Automatic cranes shall not automatically start moving when power is applied after a power failure.
ELEVATORS AND ESCALATORS
- Codes and Standards
- Design Specifications
- Emergency Power
- Design
- Fire Protection
- Inspections and Records
However, these requirements are part of the more comprehensive requirements of ANSI/ASME A17.1 for electrical safety devices, which warrant scrutiny by designers, maintenance personnel, and inspectors. The electrical designer should coordinate with the manufacturer on the design of the fire protection systems that connect to the elevator control panel.
PORTABLE AND VEHICLE-MOUNTED GENERATORS
Ground Fault Circuit Interrupter
Grounding Portable and Vehicle-Mounted Generators
BATTERIES
- Surrounding Space
- Location
- Ventilation
- Conduit
- Battery Room
- Personal Protective Equipment
- Tools
- Storage Batteries and Battery Banks
Battery installations must comply with the requirements in the current edition of the NEC and the NESC. Lockable doors must be provided to control access to rooms or enclosures containing battery banks.
WORK IN EXCESS OF 600 VOLTS 91
Workers
Supervisors
TRAINING
Employee Training
The worker must 8.2 be properly trained in the set-up and operation of insulated bucket. Employees must also be trained in, and familiar with, any other safety practices, including appropriate emergency procedures not specifically addressed in this section, but related to their work and necessary for their safety.
Qualified Employee Training
JOB BRIEFINGS
PERSONAL PROTECTIVE EQUIPMENT AND PROTECTIVE CLOTHING
- Shoes
- Hardhats
- Eye Protectors
- Conductive Articles
- Work Gloves
- Work Clothes
- Fire-Resistant (FR) Arc-Rated (AR) Clothing
- Rubber Gloves
- Rubber Line Hose, Hoods, Covers, Sleeves, and Blankets
- Live Line Tools
- Storeroom Storage
- Truck Storage
- Placing of Insulating Goods on Conductors
- Removing Insulating Goods from Conductors
- Cleaning and Inspecting
All clothing worn by affected workers should be considered part of the worker's protective clothing system. Sleeves should be stored flat with the inserts rolled up lengthwise or placed in a piping bag.
PROTECTIVE GROUNDING OF LINES AND EQUIPMENT
- Purpose
- Application
- Grounding Equipment
- Testing Before Installing Grounds
- Attaching and Removing Grounds
- Grounding Methods and Location of Grounds in Order of Preference
- Testing Without Grounds
- Ground Personnel
Ground cables should be available for use when working on de-energized wiring or equipment. No ground shall be removed until all personnel are clear of the temporarily grounded wiring or equipment.
INSTALLING OR REMOVING CONDUCTORS
Working on Energized Line or Equipment
Stringing or Removing De-energized Conductors
When practicable, the automatic reclosing feature of the circuit breaker 8.46 should be rendered inoperative. In addition, the line being tensioned 8.46 on either side of the intersection must be grounded, or considered energized and worked on.
Stringing Adjacent to Energized Lines
SPECIAL TOOLS
- Lineworkers’ Climbing Tools
- Body Belts and Safety Straps
- Tool Bag and Equipment
- Tapes and Rulers
- Spoon and Shovels
- Pike Poles
- Hand Axes and Sharp Tools
- Handlines and Taglines
Heat, sharp turns and over-tensioning of body belts and seat belts should be avoided as they are harmful to leather. When not in use, sharp tools should be protected by suitable guards or holders.
TREE TRIMMING
Care and Use of Tools
Hand lines and tag lines must be stored in a clean, dry place and protected from damage and contamination. Clean gloves must be worn when handling handlines and taglines to avoid contaminating the rope.
Climbing
UNDERGROUND
Working in Manholes, Utility Tunnels, and Vaults
When the test devices indicate a lack of oxygen, all personnel8.76 must leave the shaft until an adequate atmosphere is established. 8.84 Cables and insulated wires are considered to be live unless approved methods have been used to determine that they are de-energized.
Working on Energized Underground Cables
All cables and insulated wires that do not have an earthed conductive jacket or shield must be treated as uninsulated conductors. Before entering a manhole containing cables or wires that do not have grounded conductive sheaths, a risk assessment should be performed that takes into account the age and condition of the insulation.
Terminals of Underground Cables (Potheads)
If these conductors are within reach of an employee, they should be barricaded or covered with protective equipment or devices. If deemed necessary, appropriate PPE should be used by workers where there is a risk of shock or arc flash.
FERRO-RESONANCE
If single-pole or poorly synchronized switchgear is used, ensure that the transformer and underground cable are loaded with more than 2% resistive load of the transformer capacity; If the transformer primary is not grounded, the neutrals of the transformers being switched are temporarily grounded; or.
TEMPORARY WIRING 115
- Contact Prevention
- Vertical Clearances
- Wet Locations
- Bushings
- Lighting
- Confined Spaces
- Exposed Sockets and Broken Bulbs
- Ground Fault Protection for Personnel
- Wiring Methods
Feeders for temporary electrical installations 9.18 must originate within an approved distribution centre, such as a panel board, which is rated for the voltages and currents the system is expected to carry. Branch circuits for temporary wiring 9.19 shall originate within an approved panel or power outlet that is rated for the voltages and currents the system is expected to carry.
Using Assured Equipment Grounding Conductor Program
PORTABLE ELECTRICAL TOOLS AND EQUIPMENT
- Inspection and Maintenance
- Conditions of Use
- Use of Extension Cords
- Double Insulated Tools
The cords must 9.23 be hard or extra hard as specified in the NEC. Flexible cords used with temporary and portable lights shall 9.24 be designed for heavy duty or extra heavy duty use.
ELECTRICAL SAFETY DURING EXCAVATION 121
UTILITIES IDENTIFICATION
Configuration Management
Excavation Permit
UTILITIES VERIFICATION AND MARKING
- Field Location of Excavation Boundaries
- Locator Equipment Selection and Limitations
- Locator Operator Training
- Field Marking of Identified Utilities
It is necessary that the company has land at both ends of the section to be placed. The signal from the transmitter is induced into the service, making the location of the service possible.
UTILITIES DISPOSITION
Lawn mowing equipment can erase or diminish the effectiveness of research paints in outdoor areas. Plastic Utilities ribbon tape is used in most facilities as well as commercial and industrial applications.
WORK CONTROL DURING EXCAVATIONS
Safety Equipment and Procedures
Many cases of faint markings and/or markings washed away by rain have been documented on construction sites. Standard utility color coding is well understood by most excavation subcontractors and serves as a highly effective means of communication for the facility owner.
THE EXCAVATION PROCESS
Excavations in Concrete Walls and Slabs
In addition to other safe work practices when drilling or cutting concrete, consideration should be given to the use of a drill stop. The drill stop prevents accidental cutting of the reinforcing rod and channel by turning off power to the drill unit when metal ground is encountered.
Machine or Hand Digging
The drill stop is primarily intended to detect the presence of grounded metal in concrete and to prevent damage to this metal by terminating power to the drill motor when detected. A typical drill stop provides this protection by switching voltage potentials in excess of 10 volts to a low impedance, high current capacity ground path.
AS-BUILT DRAWINGS
ENCLOSED ELECTRICAL/ELECTRONIC EQUIPMENT 128
Objectionable Current over Grounding Conductors
The intent of NEC 250.6 is not to permit electronic equipment to be operated on AC systems or branch circuits that are not connected to an EGC required by NEC Article 250. Voltage variations, and thus opposing currents, may exist because impedances to ground are not equal throughout the grounding system, due to variations in ground resistance, improper connections, or other problems.
Enclosure Equipment Grounding and Bonding
In the enclosure to which the AC power supply is connected, the ground terminal of its socket 11.8 must be internally connected to the enclosure frame. If solder is used, the connection of the EGC 11.9 must not depend on the solder alone.
RACK POWER DISTRIBUTION
General Requirements Applying to All AC Power Equipment within or Attached to
The metal chassis must be effectively connected to a main grounding point in the rack cabinet where necessary to ensure electrical continuity and must have the capacity to safely conduct any fault currents.
Conductors, Cords and Cables Specific Requirements
In addition, the insulation 11.13 must be rated for the maximum voltage of nearby conductors and wire to which each wire may be exposed. Wiring, cords or cables must 11.16 be provided with strain relief, as necessary, to prevent damage.
Power Switches and Interlock Devices Specific Requirements
This should be achieved by using push terminal connectors, solder tabs, crimped eyelets or by soldering all strands of the wire together. In most cases, the entire length of the flexible cord must be replaced to ensure insulation integrity and serviceability.
CHASSIS POWER DISTRIBUTION
AC Power Distribution
Plugs and sockets for connecting any AC power source must11.25 be NRTL listed for the application. Plugs operating at 50 V or more must11.25 be listed, rated or recommended for their intended use.
DC Power Distribution
PROTECTIVE DEVICES FOR ENCLOSED ELECTRICAL/ ELECTRONIC EQUIPMENT
- Surge Arresters
- Fuses
- Circuit Breakers
- Power Interlock Devices
- General
- Emergency Shutdown
- Special Considerations
11.36 Locking systems must not be used as a means of disconnection for cabinets and equipment in which potentially dangerous currents and/or voltages are present. Disconnecting means shall 11.38 interrupt the source voltage for secondary or remotely controlled equipment such as thyristor control equipment.
MARKING AND LABELING REQUIREMENTS
General Marking Requirements
The emergency stop switch must: be within the operator's reach; be easily identifiable; be able to disconnect all power to all equipment connected to the system. However, the emergency stop switch should not interrupt auxiliary circuits necessary for safety (such as cooling).
Hazard Marking Requirements
If a disconnecting device is part of the equipment, it should be located as close as possible to the input power source.
Other Requirements
For rack cabinets with internal power distribution units, label the outside of the rack cabinet with the input parameters of the internal power distribution system. For rack cabinets without internal power distribution units, the outside of the rack cabinet must be labeled with the total amperage of the installed equipment.
WORKING CLEARANCE
A normal current draw can be a few amps, but when the chassis is supplying current to a load, the current draw can be much higher. Individual loads, internal and external, can be tabulated and added to determine actual chassis labeling information.
CABLE/UTILITY MANAGEMENT SYSTEM
Usage with Enclosed Electrical/Electronic Equipment
Requirements
All installations in power cable trays must follow 11.48 the NEC guidelines for cable tray filling. The cable tray must be designed and installed to minimize inductive effects during a fault condition.
ELECTRICAL SAFETY REQUIREMENTS FOR TESTER FACILITIES
- Ampacity of Facility Wiring and Distribution Equipment
- Facility Grounding at Temporary or Remote Sites
- Facility Lightning Protection
- Surge Protection
Equipment cable/supply lines installed in cable/supply management systems should be visually inspected periodically. Supports shall 11.52 be provided to prevent stress and physical damage to cables where they enter or exit cable/supply management systems.
ENCLOSED POWER ELECTRONICS
- Enclosures
- Component Clearances
- Instrumentation
- General
Enclosures must be dimensioned so that cables can be installed and routed without exceeding the required distances from high voltage conductors. Conductors, busbars and internal wiring must be insulated against objects falling into the equipment.
NON-IONIZING RADIATION
Electromagnetic Radiation
Subassemblies, circuits, and related equipment should be separated as much as possible to minimize the possibility of a fault in one device damaging another. Test points required for setup and diagnosis should be located on the front panel or other suitable location of the power electronic systems to facilitate their use without risk of exposure to employees in the area.
Electromagnetic Radiation Threat to Electro Explosive Devices
EMR safe levels have been established by the IEEE and are documented in the IEEE Standard – C95.1-1999, Standard for Safety Levels Respecting Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz. Exposure to hazardous levels of EMR can be reduced by maintaining as much distance from the source as possible.
AMPACITY INFORMATION FOR WIRE SIZING
Ampacity Information
Color Coding Guidelines
13 Blue with black tracking 14 Orange with black tracking 15 Green with black tracking 16 Brown with black tracking 17 Slate with black tracking 18 White with black tracking 19 Red with black tracking 20 Black with yellow tracking 21 Yellow with black tracking 22 Purple with black tracking 23 Rose with black tracer 24 Aqua with black tracer Table 11-3. Color Coding of Premises Fiber Optic Cable Fiber Type/Class Diameter (µm) Sheath Color Multimode 1a 50/125 Orange Multimode 1a 62.5/125 Slate.
APPROVAL OF UNLISTED ELECTRICAL EQUIPMENT 151
Special efforts may be required to ensure adequate electrical safety, beginning with the design and continuing through the development, fabrication and construction, modification, installation, inspection, testing, operation and maintenance of R&D electrical apparatus and equipment. This section contains safety criteria for the DOE complex in the design, development, fabrication, and construction, modification, installation, inspection, testing, operation, and maintenance of electrical R&D apparatus and facilities.
EMPLOYEE QUALIFICATIONS
Hazards
The DOE complex engages in a variety of R&D activities that often include the design and use of special or unusual apparatus and equipment in its facilities. Electrical systems of all types are an integral part of R&D operations and associated support work.
Additional Qualifications
GENERIC R&D EQUIPMENT
- Power Sources
- Conditions of Low-Voltage and High-Current
- Conditions of High-Voltage and Low-Current
- Radio-Frequency/Microwave Radiation and Fields
An analysis of high voltage circuits must be performed by a qualified person before work begins, unless all exposed energized parts are guarded. Warning Signs – Signs consistent with the RFMW level must be used to alert personnel of RFMW hazards.
METHODS
Wiring Methods
If these requirements are not met, the experimental equipment13.22 must be appropriately grounded using another approved method. The AHJ evaluation for safe operating conditions must13.17 include an assessment of unique features in the technical documentation.
Unconventional Practices
Near-Field, Low-Impedance, Loop-Connector) – The technique for increasing magnetic coupling resistance in shielded cables is to ground both ends of the shield to an effective signal return ground, as shown in Figure 13-4 . Before starting any operation (experiment, test, etc.) the exposed parts of the grounding system should be visually checked for any damage and to determine if all the necessary connections have been made.
Work on Energized or De-Energized Electrical Equipment
Personnel may assume that the equipment is being used as originally designed and may unwittingly expose themselves to hazards unless special precautions are followed. Signs should be posted warning of the hazards to prevent unsuspecting personnel from being injured.
REQUIREMENTS FOR SPECIFIC R&D EQUIPMENT
Capacitors
A discharge point with an impedance capable of limiting the current to 500A or less must be provided. Caution should be used in the placement of automatic discharge safety devices with respect to fuses.
Inductors
All uninstalled capacitors capable of storing 5 J or more must be short-circuited with a conductor no smaller than #14 AWG. Large amounts of stored energy can be released in the event of a "quench" in a superconducting magnet.
Electrical Conductors and Connectors
If test conditions require an ungrounded shield, barriers and warning signs shall be provided to notify personnel that the shield is ungrounded and shall be assumed to be energized. Connectors and cable ties should be checked after installation, periodically and tightened as necessary.
Induction and Dielectric Heating Equipment
When using liquid or gas cooled conductors, sensing devices (coolant temperature or flow) must be provided for alarm purposes or equipment shutdown if the cooling system is not operating properly. Heating coils, high frequency power sources, and other live parts outside the generator enclosure must be shielded or secured to prevent access or contact.
Batteries
If the physical construction of the battery system allows it, the intercell or interlevel cables must be disconnected when working on the battery system. If one terminal of the battery system is connected to ground, there is an additional hazard.
Lasers and X-Ray Equipment
Provide guidance on implementing the electrical safety requirements of Department of Energy (DOE) orders, standards, and guidance. Requirement to develop and maintain an electrical safety program; and the allocation of funds for the implementation of this program.
