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1. Introduction

OSHA requires that:

• All employees who are at risk of electrical shocks must be trained to practice electrical safety
• Qualified workers need special training as determined by the nature of their responsibilities
• Unqualified workers must be trained in electrical safety practices as covered in 29 CFR 1910.332

Qualified workers are those persons permitted to work around energized "live" electrical parts. They could implement lockout/tagout and other safety procedures. Unqualified workers may not work around live electrical parts but need to know the safety rules and obey all warning signs, tags, and stay out of hazardous areas.

Basic rules for electricity include:

• Use insulated tools and PPE when working around electricity
• Be careful of live parts in "blind" areas
• Stay at least 10 feet away from overhead power lines
• Use non-conducting or insulated tools and equipment when working near electricity
• Never use damaged power tools or electrical cords
• Do not touch electric tools, equipment, or cords that are wet, or with wet hands.

2. Policy

It is the policy of Georgia Southern University (GSU) to take every reasonable precaution in the performance of work to protect the health and safety of employees and the public and to minimize the probability of damage to property. The electrical safety requirements contained in this chapter are regulations set forth by GSU Environmental Safety Services.

3. Employee Responsibility

All Georgia Southern University (GSU) personnel are responsible for all aspects of safety within their own groups. The Responsible Safety Officer is responsible for providing information, instruction, and assistance as appropriate concerning Georgia Southern University (GSU) electrical safety requirements and procedures.

Individual employees are responsible for their own and their co-workers' safety. Everyone needs to:

1. Become acquainted with all potential hazards in the area in which they work.
2. Learn and follow the appropriate standards, procedures, and hazard control methods.
3. Never undertake a potentially hazardous operation without consulting with appropriate supervision.
4. Stop any operation you believe to be hazardous.
5. Notify a supervisor of any condition or behavior that poses a potential hazard.
6. Wear and use appropriate protective equipment.
7. Immediately report any occupational injury or illness to the appropriate supervisor.

4. Employee Responsibilities

Acting in a supervisory capacity has specific safety responsibilities. These include:

1. Developing an attitude and awareness of safety in the people supervised and seeing that individual safety responsibilities are fully carried out.
2. Maintaining a safe work environment and taking corrective action on any potentially hazardous operation or condition.
3. Ensuring that the personnel he/she directs are knowledgeable and trained in the tasks they are asked to perform.
4. Ensuring that safe conditions prevail in the area and that everyone is properly informed of the area's safety regulations and procedures.
5. Ensuring that contract personnel are properly protected by means of instructions, signs, barriers, or other appropriate resources.
6. Ensuring that no employee assigned to potentially hazardous work appears to be fatigued, ill, emotionally disturbed, or under the influence of alcohol or drugs (prescription, over the counter medicinal, or otherwise). `

Management at every level has the responsibility for maintaining the work environment at a minimal level of risk throughout all areas of control.

5. Management Responsibilities

1. Is responsible for being aware of all potentially hazardous activities within the area of responsibility.
2. May assign responsibility or delegate authority for performance of any function
3. But remains accountable to higher management for any oversight or error that leads to injury, illness, or damage to property.

6. Procedures

It is the policy of Georgia Southern University (GSU)to follow the fundamental principles of safety which are described below. A clear understanding of these principles will improve the safety of working with or around electrical equipment:

1. Practice proper housekeeping and cleanliness. Poor housekeeping is a major factor in many accidents. A cluttered area is likely to be both unsafe and inefficient. Every employee is responsible for keeping a clean area and every supervisor is responsible for ensuring that his or her areas of responsibility remain clean.


2. Identify hazards and anticipate problems. Think through what might go wrong and what the consequences would be. Do not hesitate to discuss any situation or question with your supervisor and co-workers.


3. Resist "hurry-up" pressure. Program pressures should not cause you to bypass thoughtful consideration and planned procedures.


4. Design for safety. Consider safety to be an integral part of the design process. Protective devices, warning signs, and administrative procedures are supplements to good design but can never fully compensate for its absence. Completed designs should include provisions for safe maintenance.


5. Maintain for safety. Good maintenance is essential to safe operations. Maintenance procedures and schedules for servicing and maintaining equipment and facilities, including documentation of repairs, removals, replacements, and disposals, should be established.


6. Document your work. An up-to-date set of documentation adequate for operation, maintenance, testing, and safety should be available to anyone working on potentially hazardous equipment. Keep drawings and prints up-to-date. Dispose of obsolete drawings and be certain that active file drawings have the latest corrections.


7. Have designs reviewed. All systems and modifications to systems performing a safety function or controlling potentially hazardous operations must be reviewed and approved at the level of project engineer or above.


8. Have designs and operation verified. All systems performing safety functions or controlling a potentially hazardous operation must be periodically validated by actual test procedures at least once a year, and both the procedures and actual tests must be documented.


9. Test equipment safety. Tests should be made when the electrical equipment is de-energized or, at most, energized with reduced hazard.


10. Know emergency procedures. All persons working in areas of high hazard (with high-voltage power supplies, capacitor banks, etc.) must be trained in emergency response procedures, including cardiopulmonary resuscitation (CPR) certification.


11. Georgia Southern University (GSU) does not permit working with Energized Equipment without written approval by an authorized person.

7. Definitions

The following definitions are used in this discussion of electrical safety.

Authorized Person: An individual recognized by management as having the responsibility for and expertise to perform electrical procedures in the course of normal duties. Such individuals are normally members of electronic or electrical groups.

Backup Protection: A secondary, redundant, protective system provided to de-energize a device, system, or facility to permit safe physical contact by assigned personnel. A backup protective system must be totally independent of the first-line protection, and must be capable of functioning in the event of total failure of the first-line protective system.

Companion: A coworker who is cognizant of potential danger and occasionally checks the other worker.

Electrical Hazard: A potential source of personnel injury involving, either directly or indirectly, the use of electricity.

Direct Electrical Hazard: A potential source of personnel injury resulting from the flow of electrical energy through a person (electrical shocks and burns).

Indirect Electrical Hazard: A potential source of personnel injury resulting from electrical energy that is transformed into other forms of energy (e.g., radiant energy, such as light, heat, or energetic particles; magnetic fields; chemical reactions such as fire, explosions, the production of noxious gases and compounds; and involuntary muscular reactions).

First Line Protection: The primary protective system and/or operational procedure provided to prevent physical contact with energized equipment.

General Supervision: The condition that exists when an individual works under a supervisor's direction, but not necessarily in the continuous presence of the supervisor.

Grounding Point: The most direct connection to the source of a potential electrical hazard such as the terminals of a capacitor. A yellow circular marker must indicate such a point.

Grounds, Electrical: Any designated point with adequate capacity to carry any potential currents to earth. Designated points may be building columns or specially designed ground-network cabling, rack, or chassis ground. Cold water pipes, wire ways, and conduits must not be considered electrical grounds.

Grounds, Massive: Large areas of metal, concrete, or wet ground that make electrical isolation difficult or impossible.

Implied Approval: Approval is implied when a supervisor, knowing the qualifications of an individual, assigns that individual a task or responsibility for a device, system, or project.

Qualified Person: An individual recognized by management as having sufficient understanding of a device, system, or facility to be able to positively control any hazards it may present.

Safety Watch: An individual whose sole task is to observe the operator and to quickly de-energize the equipment, using a crash button or circuit breaker control in case of an emergency, and to alert emergency personnel. This person should have basic CPR training.

8. Types of Hazards

The degree of hazard associated with electrical shock is a function of the duration, magnitude, and frequency of the current passed by the portion of the body incorporated in the circuit. The current that can flow through the human body with contacts at the extremities, such as between the hand or head and one of both feet, depends largely on the voltage. Body circuit resistance, even with liquid contacts (barring broken skin) will probably be not less than 500 ohms. The current flow at this resistance at 120 volts is 240 milliamperes. Recognition of the hazards associated with various types of electrical equipment is of paramount importance in developing and applying safety guidelines for working on energized equipment. Three classes (in order of increasing severity) of electrical hazards have evolved.

Class A Hazard

A Class A electrical hazard exists when all the following conditions prevail:

• The primary AC potential does not exceed 130 volts rms.
• The available primary AC current is limited to 30 amperes rms.
• The stored energy available in a capacitor or inductor is less than 5 joules (J-CV2/2=LI2/2).
• The CD or secondary AC potentials are less than 50 volts line-to-line and/or to ground or the DC or secondary AC power is 150 volt-amperes (V-A) or less.

Although the voltage and currents may be considered nominal, a "Class A" electrical hazard is potentially lethal. This class is particularly dangerous because of everyday familiarity with such sources, an assumed ability to cope with them, and their common occurrence in less guarded exposures.

Class B Hazard

A Class B electrical hazard has the same conditions as a Class A hazard except that the primary AC potential is greater than 130 volts rms, but does not exceed 300 volts rms.

Class C Hazard

Class C electrical hazard classifications prevail for all situations when one or more of the limitations set in Class B is exceeded.

9. Employee Attitude

The attitudes and habits of personnel and the precautions they routinely take when working on energized equipment are extremely important. There are three modes of working on electrical equipment.

Mode 1: Turn off the Power

All operations are to be conducted with the equipment in a positively de-energized state. All external sources of electrical energy must be disconnected by some positive action (e.g., locked-out breaker) and with all internal energy sources rendered safe. "Mode 1" is a minimum hazard situation.

Mode 2: Latent Danger

All manipulative operations (such as making connections or alterations to or near normally energized components) are to be conducted with the equipment in the positively de-energized state. Measurements and observations of equipment functions may then be conducted with the equipment energized and with normal protective barriers removed. "Mode 2" is a moderate-to-severe hazard situation depending on the operating voltages and energy capabilities of the equipment.

Mode 3: Hot Wiring

"Mode 3" exists when manipulative, measurement, and observational operations are to be conducted with the equipment fully energized and with the normal protective barriers removed. "Mode 3" is a severe hazard situation that should be permitted only when fully justified and should be conducted under the closest supervision and control. One knowledgeable person should be involved in addition to the worker(s). Written permission may be required. Work on Class B or Class C energized circuitry must only be done when it is absolutely necessary.

10. Personal Protective Devices

For work on any energized circuitry with a Class B or Class C hazard, the use of personal protective devices (e.g., face shields, blast jackets, gloves, and insulated floor mats) is encouraged, even if not required.

Safety Glasses

Either safety glasses or a face shield must be worn when working on electrical equipment.

Elevated Locations

Any person working on electrical equipment on a crane or other elevated location must take necessary precautions to prevent a fall from reaction to electrical shock or other causes. A second person, knowledgeable as a safety watch, must assume the best possible position to assist the worker in case of an accident.

11. Chain of Command (MISC)

• The supervisory chain must be identified for normal operation and development, servicing, or testing of hazardous equipment.
• An up-to-date set of instructions for operation, maintenance, testing, and safety should be provided and made readily available to anyone working on hazardous equipment.
• As many tests as practicable should be made on any type of electrical equipment in the unenergized condition or, at most, energized with reduced hazard.
• All covering, clothing, and jewelry that might cause hazardous involvement must be removed.
• Adequate and workable lockout/tagout procedures must be employed.
• A person in a hazardous position who appears to be fatigued, ill, emotionally disturbed, or under the influence of alcohol and/or drugs (medicinal or otherwise) must be replaced by a competent backup person or the hazardous work must be terminated.
• Supervisors and workers must be encouraged to make the conservative choice when they are in doubt about a situation regarding safety.
• Training sessions and drills must be conducted periodically to help prevent accidents and to train personnel to cope with any accidents that may occur. CPR instruction must be included.
• An emergency "OFF" switch, clearly identified and within easy reach of all high-hazard equipment, should be provided. Also, this switch may be used to initiate a call for help. Resetting an Emergency "OFF" switch must not be automatic but must require an easily understandable overt act.
• Automatic safety interlocks must be provided for all access to high-hazard equipment. Any bypass of such an interlock should have an automatic reset, display conspicuously the condition of the interlocks, and ensure that barriers cannot be closed without enabling the interlock.
• All equipment should have convenient, comfortable, and dry access.
• Communication equipment (e.g., fire alarm box, telephone) should be provided near any hazardous equipment. Its location should be clearly marked to ensure that the person requesting assistance can direct the people responding to a call for help to the emergency site quickly.
• Any component that in its common use is non-hazardous, but in its actual use may be hazardous, must be distinctively colored and/or labeled. (An example might be a copper pipe carrying high voltage or high current.
• Periodic tests of interlocks to ensure operability must be performed and documented at least yearly.
• Equipment must be designed and constructed to provide personnel protection. First-line and backup safeguards should be provided to prevent personnel access to energized circuits.
• Period tests must be established to verify that these protective systems are operative.

12. Safety Practices

Additional safety practices are described below.

Cable Clamping: A suitable mechanical-strain-relief device such as a cord grip, cable clamp, or plug must be used for any wire or cable penetrating an enclosure where external movement or force can exert stress on the internal connection. Grommets, adlets, or similar devices must not be used as strain relief.

Emergency Lighting: There must be an emergency lighting system that activates when normal power fails in Class C conditions.

Flammable and Toxic Material Control: The use of flammable or toxic material must be kept to a minimum. When components with such fluids are used, a catch basin or other approved method must be provided to prevent the spread of these materials should the normal component case fail.

Isolation: covers and enclosures must isolate all sources of dangerous voltage and current. Access to lethal circuits must be either via screw-on panels, each containing no less than four screws or bolts, or by interlocked doors. The frame or chassis of the enclosure must be connected to a good electrical ground with a conductor capable of handling any potential fault current.

Lighting: Adequate lighting must be provided for easy visual inspection.

Overload Protection: Overload protection and well marked disconnects must be provided. Local "OFF" controls must be provided on remote-controlled equipment. All disconnects and breakers should be clearly labeled as to which loads they control.

Power: All ac and dc power cabling to equipment not having a separate external ground, but having wire-to-wire or wire-to-ground voltage of 50 volts or more must carry a ground conducted unless cabling is inside an interlocked enclosure, rack, grounded wire way, or conduit, or feeds a commercial double-insulated or UL-approved device. This requirement will ensure that loads such as portable test equipment, temporary or experimental, is grounded. UL-approved devices such as coffeepots, timers, etc., used per the manufacturer's original intent are permissible.

Rating: All conductors, switches, resistors, etc., should be operated within their design capabilities. Pulsed equipment must not exceed either the average, the rms, or the peak rating of components. The equipment should be rated as necessary for the environment and the application of the components.

Safety Grounding: Automatic discharge devices must be used on equipment with stored energy of 5 joules or more. Suitable and visible manual grounding devices must also be provided to short-to-ground all dangerous equipment while work is being performed.

Safety Practices, High Voltage: The following checklist must be used as a guide for circuits operating at 130 volts or more or storing more than 5 joules. An enclosure may be a room, a barricaded area, or an equipment cabinet.

Access: Easily opened doors, panels, etc., must be interlocked so that the act of opening de-energizes the circuit. Automatic discharge of stored-energy devices must be provided. Doors should be key-locked, with the same required key being also used for the locks in the control-circuit-interlock chain. This key must be removable from the door only when the door is closed and locked.

Heat: Heat-generating components, such as resistors, must be mounted so that heat is safely dissipated and does not affect adjacent components.

Isolation: The enclosure must physically prevent contact with live circuits. The enclosure can be constructed of conductive or non-conductive material. If conductive, the material must be electrically interconnected and connected to a good electrical ground. These connections must be adequate to carry all potential fault currents.

Seismic Safety: All racks, cabinets, chassis and auxiliary equipment must be secured against movement during earthquakes.

Strength: Enclosures must be strong enough to contain flying debris due to component failure.

Temporary Enclosure: Temporary enclosures (less than 6-months duration) not conforming to the normal requirements must be considered Class C hazards.

Ventilation: Ventilation must be adequate to prevent overheating of equipment and to purge toxic fumes produced by a fault.

Visibility: Enclosures large enough to be occupied by personnel must allow exterior observation of equipment and personnel working inside the enclosure.

Warning Indicators: When systems other than conventional facilities represent Class C hazards, the systems should be provided with one of the following two safety measures: (1) a conspicuous visual indicator that is clearly visible from any point where a person might make hazardous contact or entry; and (2) A clearly visible primary circuit breaker or "OFF" control button on the front of the enclosure.

13. Safety Practices (Continued)

Because a wide range of power supplies exist, no one set of considerations can be applied to all cases. The following classification scheme may be helpful in assessing power-supply hazards. Power supplies of 50 volts or less with high current capability too often are not considered a shock hazard although these voltages are capable of producing fatal shocks. Since they are not "high voltage," such power sources frequently are not treated with proper respect.

In addition to the obvious shock and burn hazards, there is also the likelihood of injuries incurred in trying to get away from the source of a shock. Cuts or bruises, and even serious and sometimes fatal falls, have resulted from otherwise insignificant shocks. Power supplies of 300 volts or more, with legal current capability, have the same hazards to an even greater degree. Because supplies in this category are considered Class C hazards, they must be treated accordingly.

High-voltage supplies that do not have dangerous current capabilities are not serious shock or burn hazards in themselves and are, therefore, often treated in a casual manner. However, they are frequently used adjacent to lower-voltage lethal circuits, and a minor shock could cause a rebound into such a circuit. Also, an involuntary reaction to a minor shock could cause a serious fall (for example, from a ladder or from experimental apparatus).

The following are additional safety considerations for power supplies:

1. Primary Disconnect: A means of positively disconnecting the input must be provided. This disconnect must be clearly marked and located where the workmen can easily lock or tag it out while servicing the power supply. If provided with a lockout device, they key must not be removable unless the switch or breaker is in the "OFF" position.

2. Overload Protection: Overload protection must be provided on the input and should be provided on the output.

3. Danger with Large Capacitors

   This section describes the hazards associated with capacitors capable of storing more than 5 joules of energy.

   Capacitors may store hazardous energy even after the equipment has been de-energized and may build up a dangerous residual charge without an external source; "grounding" capacitors in series, for example, may transfer rather than discharge the stored energy. Another capacitor hazard exists when a capacitor is subjected to high currents that may cause heating and explosion. At one time, capacitors were called condensers and older capacitors may still bear this label in diagrams and notices.

   Capacitors may be used to store large amounts of energy. An internal failure of one capacitor in a bank frequently results in explosion when all other capacitors in the bank discharge into the fault. Approximately 10 sup 4 joules is the threshold energy for explosive failure of metal cans. Because high-voltage cables have capacitance and thus can store energy, they should be treated as capacitors.

   The liquid dielectric in many capacitors, or its combustion products, may be toxic. Do not breathe the fumes from the oil in older capacitors.

4. Automatic Discharge: Permanently connected bleeder resistors should be used when practical. Capacitors in series should have separate bleeders. Automatic shoring devices that operate when the equipment is de-energized or the enclosure is opened should be used. In the case of Class C equipment with stored energy in excess of 5 joules, an automatic, mechanical discharging device must be provided that functions when normal access ports are opened.

   The device must be contained locally within a protective barrier to ensure wiring integrity and should be in plain view of the person entering the protective barrier so that the individual can verify its proper functioning. Protection also must be provided against the hazard of the discharge itself.

5. Safety Grounding: Fully visible, manual-grounding devices must be provided to render the capacitors safe while they are being worked on. Grounding points must be clearly marked, and caution must be used to prevent transferring charges to other capacitors.

   Ground Hooks - All ground hooks must:

   • Have conductors crimped and soldered.
   • Be connected such that impedance is less than 0.1 ohms to ground.
   • Have the cable conductor clearly visible through its insulation.
   • Have a cable conductor size of at least #2 extra flexible, or in special conditions, a conductor capable of carrying any potential current.
   • Be in sufficient number to ground conveniently and adequately ALL designated points.
   • Be grounded and located at normal entryway when stored in such a manner to ensure that they are used.

In Class C equipment with stored energy in excess of 5 joules, a discharge point with an impedance capable of limiting the current to 500 amperes or less should be provided. This discharge point must be identified with a yellow circular marker with a red slash and must be labeled "HI Z PT" in large readable letters. A properly installed grounding hook must first be connected to the current-limiting discharge point and then to a low-impedance discharge point (less than 0.1 ohm) that is identified by a yellow circular marker. The grounding hooks must be left on all of these low impedance points during the time of safe access. The low-impedance points must be provided, whether or not the HI-Z current-limiting points are needed. Voltage indicators that are visible from all normal entry points should also be provided.

6. Fusing: Capacitors used in parallel should be individually fused when possible to prevent the stored energy from dumping into a faulted capacitor. Care must be taken in placement of automatic-discharge safety devices with respect to fuses. If the discharge will flow through the fuses, a prominent warning sign must be placed at each entry indicating that each capacitor must be manually grounded before work can begin. Special knowledge is required for high-voltage and high-energy fusing.

7. Unused Terminal Shorting: Terminals of all unused capacitors representing a Class C hazard or capable of storing 5 joules or more must be visibly shorted.

8. Danger with Large Magnets

   This section describes inductors and magnets that can store more than 5 joules of energy or that operate at 130 volts or more.

   The following are some hazards peculiar to inductors and magnets.

   • The ability of an inductor to release stored energy at a much higher voltage than that used to charge it.
   • Stray magnetic fields that attract magnetic materials.
   • Time-varying stray fields that induce eddy currents in conductive material thereby causing heating and mechanical stress.

   • Time-varying magnetic fields that may induce unwanted voltages at inductor or magnet terminals.

9. Automatic Discharge: Freewheeling diodes, varistors, thyrites, or other automatic shorting devices must be used to provide a current path when excitation is interrupted.

10. Connections: Particular attention should be given to connections in the current path of inductive circuits. Poor connections may cause destructive arcing.

11. Cooling: Many inductors and magnets are liquid cooled. Thermal interlocks on the outlet of each parallel coolant path should protect the unit and a flow interlock should be included for each device.

12. Eddy Currents: Units with pulsed or varying fields should have a minimum of eddy-current circuits. If large eddy-current circuits are unavoidable, they should be mechanically secure and able to safety dissipate any heat produced.

13. Grounding: The frames and cores of magnets, transformers, and inductors should be grounded.

14. Rotating Electrical Machinery: Beware of the hazard due to residual voltages that exists until rotating electrical equipment comes to a full stop.

15. Safety Design: Proper philosophy is vital to the safe design of most control applications. The following checklist should be used as a guide.

16. Checkout: Interlock chains must be checked for proper operation after installation, after any modification, and during periodic routine testing.

17. Fail-safe Design: All control circuits must be designed to be "fail-safe." Starting with a breaker or fuse, the circuit should go through all the interlocks in series to momentary on-off switches that energize and "seal in" a control relay. Any open circuit or short circuit will de-energize the control circuit and must be reset by overt act.

18. Interlock Bypass Safeguards: A systematic procedure for temporarily bypassing interlocks must be established. Follow-up procedures should be included to ensure removal of the bypass as soon as possible. When many control-circuit points are available at one location, the bypassing should be made through the normally open contacts of relays provided for this purpose. In an emergency, these relays can be opened from a remote control area.

19. Isolation: Control power must be isolated from higher power circuits by transformers, contractors, or other means. Control power should be not more than 120 volts, ac or dc. All circuits should use the same phase or polarity so that no additive voltages (Class B or Class C hazard) are present between control circuits or in any interconnect system. Control-circuit currents should not exceed 5 amperes.

20. Lockout: A keyed switch should be used in interlock chains to provide positive control of circuit use. To ensure power removal before anyone enters the enclosure, this same key should also be used to gain access to the controlled equipment.

21. Motor Control Circuits (Class B or Class C Hazards): All Class B or Class C motor circuits must have a positive disconnect within view of the motor or, if this is not practical, a disconnect that can be locked open by the person working on these motor circuits is acceptable.

22. Overvoltage Protection: Control and instrumentation circuits used with high-voltage equipment must have provisions for shoring fault-induced high voltages to ground. High-voltage fuses with a high-current, low-voltage spark gap downstream from the high-voltage source are recommended. This also applies to all circuits penetrating high-voltage enclosures.

23. Voltage Divider Protection: The output of voltage dividers used with high voltages must be protected from overvoltage-to-ground within the high-voltage area by spark gaps, neon bulbs, or other appropriate means.

24. Current Monitors: Currents should be measured with a shunt that has one side grounded or with current transformers that must be either loaded or shorted at all times.

25. Instrument Accuracy: Instrumentation should be checked for function and calibration on a routine basis.

26. Radiation Hazards: This section covers radiation hazards that may be encountered in working with electrical equipment. The following information should be used as a rough guide to radiation safety.

    Hazardous electromagnetic radiation must be isolated in shielded enclosures. Transmission paths of microwave energy must be enclosed or barricaded and well marked. Care must be taken to avoid reflecting energy out of this path. Suitable goggles must be worn where exposure is possible. Dose rated must not exceed those shown below.

27. Monitoring: When equipment capable of generating a radiation hazard is used, monitoring must be provided to detect and measure the radiation. Where personnel may be exposed, this monitoring equipment should be arranged to de-energize the generating equipment at a safe, preset level.

28. Isolation: Equipment that produces x-rays (high-voltage vacuum tubes operating at more than 15,000 volts) or any equipment that under fault conditions could produce x-rays (e.g., spectrometers) must be isolated from personnel. This isolation may be by distance or by lead shielding. For any questions, call the Radiation Safety Officer.

    Barriers that are opaque to the radiation must isolate high-power sources of ultraviolet, infrared, and visible light. When a beam of this radiation is projected out of an enclosure, the beam path must be barricaded and well marked. Care must be taken to eliminate reflective surfaces along the beam path. Suitable goggles must be worn where exposure is possible.

29. More than 300 Volts: To work on systems with voltages greater than 300 volts (CLASS B or C HAZARD): Open the feeder breaker, roll out if possible, tag out, and lock in if in enclosure. If work is on circuits of 600 V or more, positive grounding cables should be attached to all three phases.

    Tag should contain who, why, and when information and it is of vital importance because a person's life may depend on it. "Vital" in this case means that the presence and status of the tag are inviolate, and the tag must not be altered or removed except by the person who attached it.

30. Less than 300 Volts: To work on systems with voltages less than 300 volts (CLASS A HAZARD): Turn off and tag the feeder breaker. Tag is inviolate except on projects where established circuit checkout procedure allows a qualified person to remove it and energize circuit after checkout is complete.

31. Motor Generator Systems: For motor or generator work, primary feeder breaker must be opened, tagged, and locked out if possible. For generator-load work, motor-start permissive key must be removed by person doing work and restored when work is complete.

32. High Voltage: To work on high voltage power supplies and enclosures, use Class B or Class C hazard procedure specified in the safety requirements.

    Access should always be by permissive key that interrupts input power when key is removed from control panel. Grounding of power supply output must occur either automatically when key is removed from control panel or manually before access door can be opened.

33. High Current : To work on high current power supplies (normally for magnets), treat system as a high voltage power supply if energy storage is 5 joules or more when system is off. If not, then requirements for working on magnet are as follows: If power supply is equipped with Kirk (trademark) or equivalent interlock, turn key and remove. This locks the input breaker in "off" position until key is reinserted and turned.

    If power supply is not equipped with a Kirk (trademark) or equivalent interlock, turn off and tag input circuit breaker.

34. Working on Power Supplies: The minimum requirements for working on any power supply is to turn power off and properly tag feeder circuit breaker external to power supply.

35. Electrical Lockout/Tagout Procedures: When you have to do maintenance work on a machine, take these four steps to protect yourself and your coworkers from injury. De-energize the machine, if possible. Positively disconnect the machine from the power source. If there is more than one source of power, then disconnect them all. If possible, lock out all disconnect switches. You must be given a lock and a key for each disconnect before you begin working on the machine.

    Tag all disconnect switches. Use the yellow or red safety tags which state in large letters - "Danger . . . Do Not Operate", or "Danger. . .Do Not Energize" and which give the name of the individual who locked out the equipment, date and time. The tag must also state "DO NOT REMOVE THIS TAG." (The person who placed the tag may remove it only after the machinery maintenance has been completed.

    Test the equipment to ensure it is de-energized before working on it. First, attempt to operate the equipment by turning it on normally. Next, check all electrical lines and exposed areas with test equipment or a "lamp." Finally, short to ground any exposed connections using insulated grounding sticks. This test must be done even if the electrical connection is physically broken, such as pulling out a plug, because of the chance of discharging components.

    A TAGOUT ONLY PROCEDURE MAY BE USED IF THE MACHINE CANNOT BE LOCKED OUT. IF THE MACHINE IS SUPPLIED ELECTRICAL POWER FROM A SINGLE SOURCE, WHICH IS UNDER THE EXCLUSIVE CONTROL OF A TRAINED AND QUALIFIED REPAIR PERSON AT ALL TIMES AND THERE ARE NOT ANY OTHER PERSONS IN THE REPAIR AREA WHO COULD BE HARMED BY THE ACCIDENTAL ENERGIZING OF THE MACGIZING OF THE MACHINERY, THEN TAGOUT MAY BE USED INSTEAD OF LOCKOUT/TAGOUT.

36. Re-Energizing: Many accidents occur at the moment of re-energizing. If the machinery is to be re-energized, all persons must be kept at a safe distance away from the machinery. The re-energization can be performed only by a person who either performed the lockout-tagout, a person acting under the immediate and direct command of the original lockout/tagout person or, in the event of a shift change or other unavailability of the original person, then the original shall, before leaving, appoint a surrogate original person and show him or her all steps taken to lockout/tagout the equipment.