2 LBNL Electrical Safety Manual Revision 1.pdf

LAWRENCE BERKELEY NATIONAL LABORATORY

ELECTRICAL SAFETY MANUAL

Revision: Rev 1 Date: January 2017

TABLE OF CONTENTS

Revision History

1 Introduction

1.1 Purpose

1.2 Scope

1.3 Regulatory Drivers

1.4 Format

PART I – ELECTRICAL HAZARDS

2 Electrical Hazards

2.1 Scope

2.2 Electrical Shock

2.3 Electrical Burn

2.4 Delayed Effects

2.5 Battery Hazards

2.6 Other Hazards

3 Electrical Hazard Classification

3.1 Explanation of the electrical hazard classification structure

3.2 Classification Matrix

3.3 Hazard Class 1.x, 50-60 Hz Nominal Power

3.4 Hazard Class 2.x, DC

3.5 Hazard Class 3.x, Capacitors

3.6 Hazard Class 4.x, Batteries <100 VDC

3.7 Hazard Class 5.x, RF Circuits (3 kHz to 100 MHz)

3.8 Hazard Class 6.x, Sub-RF Circuits (1 Hz to 3 kHz)

PART II – ELECTRICAL SAFE WORK PRACTICES

4 Electrical Safety Principles & Controls

4.1 Principles of Electrical Safety

4.2 Application of ISM to Electrical Safety

4.3 Planning Electrical Work

4.4 Hierarchy of controls

4.5 Authorization

4.6 Executing the Plan

4.7 Self-Controls for the Qualified Electrical Worker

5 General Electrical Safety for All Persons

5.1 Scope

5.2 General requirements

5.3 Recognizing electrical hazards

5.4 Portable electric equipment

5.5 Extension cords for temporary use

5.6 Relocatable Power Taps (Power Strips)

5.7 Adapter Cord Sets

5.8 Ground Fault Circuit Interrupters

5.9 Heating Tapes and Cords

5.10 Portable Heating Devices

5.11 Holiday Lights

5.12 Working Space Around Electrical Equipment

5.13 Switching

6 Electrical Safe Work Controls

6.1 Scope

6.2 Qualified Electrical Workers (QEWs)

6.3 Electrical Work and Requirement for a QEW

6.4 Mode 0 – Electrically Safe Work Condition

6.5 Mode 1 – Process for Establishing an Electrically Safe Work Condition (LOTO)

6.6 Mode 2 – Energized Diagnostics (Testing & Troubleshooting)

6.7 Mode 3 – Energized Repair Work (EEWP)

6.8 Electrical Safe Work Procedure (ESWP)

6.9 Person in Charge (PIC)

6.10 QEW Skill of the Craft

6.11 Direct Field Supervision

6.12 Job Briefing

6.13 Working Alone or Accompanied

7 Shock Protection

7.1 Performing a Shock Hazard Analysis

7.2 Determination of a Shock Hazard

7.3 Shock Protection Boundaries

7.4 When Voltage Rated Gloves Are Required

7.5 When Leather Protector Gloves Are Required

7.6 When Voltage Rated Blankets or Sheeting Are Required

7.7 When Insulated Sticks (Hot Sticks) Are Required

7.8 Selection of Shock Protection PPE

7.9 Primary vs. Secondary Shock Protection

8 Arc Flash Protection

8.1 Arc Flash Hazard Analysis

8.2 Determination of an Arc Flash Hazard

8.3 Incident Energy Analysis

8.4 Arc Flash Boundary

8.5 Working Distance

8.6 Incident Energy Analysis for Facility Power Systems

8.7 Incident Energy Analysis for R&D Systems

8.8 Energy Reducing Maintenance Switches

8.9 Arc Flash Labeling

8.10 Arc Flash PPE Selection

8.11 Arc flash incident energy >40 cal/cm2

8.12 MCC Buckets, Busway Plug-In Units and Drawout Type Circuit Breakers

8.13 Daily Arc-Rated Work Wear for Electrical Work

8.14 Body Positioning for Arc Flash

9 Zero Voltage Verification (ZVV)

9.1 Purpose

9.2 Live-Dead-Live Test Method

9.3 Steps to perform ZVV

9.4 Where to perform ZVV

9.5 When to perform ZVV

9.6 Types of Voltage Detectors

9.7 ZVV where there is no exposed conductor

10 General Electrical Safe Work Practices

10.1 Minimum PPE for Electrical Work

10.2 Body Positioning

10.3 Controlling the Work Area (Alerting Techniques)

10.4 Other Precautions for Personnel Activities

11 High Voltage Facilities Distribution Systems (>750 VAC)

11.1 Scope

11.2 Qualification requirements

11.3 Restricted Access to High Voltage Enclosures

11.4 Switching

11.5 Zero Voltage Verification

11.6 Personal Protective Equipment

11.7 Temporary Personal Protective Grounding of High Voltage Circuits

12 High Voltage/Low Current DC Systems (>1000 VDC, <40 mA)

12.1 Hazards

12.2 Design Considerations

12.3 Safety Practices

13 Distributed Generation

13.1 Permanently connected standby generators

13.2 Portable generator connection and operation

13.3 Uninterruptible Power Systems (UPS)

14 Batteries

14.1 Scope

14.2 Qualification & Training

14.3 Hazards

14.4 Operation and Maintenance

15 Capacitors

15.1 Scope

15.2 Qualification & Training

15.3 Hazards

15.4 Stored Energy Hazard Assessment

15.5 Capacitor Discharge Time

15.6 Capacitor Hazard Labeling

15.7 Hard Grounding vs Soft Grounding

15.8 Establishing an Electrically Safe Work Condition (Mode 1)

15.9 Testing capacitors (Mode 2)

15.10 Personal Protective Equipment (PPE)

15.11 Storage & Disposal

16 Inductors

16.1 Scope

16.2 Hazards

16.3 Design and Construction

17 Personal Protective Equipment

17.1 Rubber Insulating Gloves

17.2 Rubber Insulating Blankets

17.3 Rubber Insulating Sheeting

17.4 PVC Insulating Sheeting

17.5 Arc-Rated PPE

17.6 Other PPE

18 Electrical Tools & Equipment

18.1 Testing Equipment

18.2 Insulated Tools

18.3 Insulated Sticks

18.4 Temporary Personal Protective Grounds for R&D Equipment (Ground Hooks)

18.5 Temporary Personal Protective Grounds for Utilities (Ground Straps)

18.6 Other Tools

PART III – DEFINITIONS AND APPENDICES

Acronyms and Abbreviations

Definitions

Appendix A: Standards on Personal Protective Equipment

19 Appendix B: Standards on Other Protective Equipment

Appendix C: In-Service Specifications for Personal and Other Protective Equipment

Appendix D: Reference Sheet for the QEW Skill of the Craft Work

Appendix E: List of Pre-Approved Voltage Detectors for Zero Voltage Verification

Revision History Revision Date

Published Summary

Initial July 2015 Initial edition – implementation of NFPA 70E-2012, Standard for Electrical Safety in the Workplace, and DOE-HDBK-1092-2013, Electrical Safety Handbook. Additional material from IEEE Std 3007.3-2012, Recommended Practice for Electrical Safety in Industrial and Commercial Power Systems.

Rev 1 Jan 2017 Revision 1 of the Electrical Safety Manual incorporates a number of refinements and edits, including:

• Incorporated ESM Correction Notice 1-2015, adding balaclava for level 1 of arc flash PPE

• Incorporated ESM Correction Notice 2-2015, requiring rackout of rackable breakers for LOTO

• Changed capacitor thresholds to 10 J, 100 V

• Complete rewrite of Section 15 for Capacitors

• Clarified requirements for extension cords and temporary wiring

• Clarified requirements for relocatable power taps

• Clarified requirements for non-QEW switching thresholds

• Refined the definition of “electrical work”

• Added QEW-R level for researchers not exposed to line source hazards

• Added in QEW exceptions from PUB-3000 Chapter 8

• Refined definition of Direct Field Supervision

• Job briefing requires a detailed discussion of the scope of work

• Safety Watch only needs to know the location of an AED unless performing

Mode 3 (EEWP) work.

• Refined requirements for when to wear rubber insulating gloves

• Added ANSI 535.5 details for temporary barricade tape and signage

• Added specifications for ground hooks for R&D equipment

• Modified requirements for temporary personal safety grounds for facilities equipment

• Cord-and-plug exemption extended to multiple plugs provided exclusive control can be maintained

• Clarified two-person and barricade requirements for visual inspections

• Added requirement for arc-rated safety vests and cold-weather gear for personnel assigned with daily arc-rated wear.

• Removed requirement for minimum PPE when working on cord-and-plug

120 V equipment that has been unplugged.

• Clarified ZVV requirements and supplementary voltage checks.

1 Introduction

1.1 Purpose

1.1.1 The purpose of this Electrical Safety Manual is to establish Berkeley Lab site-specific electrical safe work practices that meet regulatory requirements and match the types of hazards found on site.

1.1.2 The electrical safe work practices prescribed in this manual are mandatory, unless specifically indicated as a recommended practice.

1.2 Scope

1.2.1 This manual establishes electrical safe work practices for both Qualified Electrical Workers (QEWs) and Non-QEWs.

1.2.2 It includes work on facilities distribution and premises wiring, and commercial and R&D type equipment.

1.2.3 Institutional requirements for the overall Electrical Safety Program are found in Chapter 8, Electrical Safety Program and are not repeated in this manual. These include:

a. Scope and structure of the overall Electrical Safety Program

b. Roles and responsibilities, including Electrical Safety Officers and Electrical Safety Advocates

c. Electrical Authority Having Jurisdiction (AHJ)

d. Training and qualification requirements

e. Emergency response to an electrical shock incident

f. Electrical incident severity score calculation

g. Subcontractor requirements http://www2.lbl.gov/ehs/pub3000/CH08/CH8.html http://www2.lbl.gov/ehs/pub3000/CH08/CH8.html

1.3 Regulatory Drivers

1.3.1 DOE 10 CFR 851, Worker Safety and Health Program

1.3.2 NFPA 70, National Electrical Code (NEC), 2011 edition

1.3.3 NFPA 70E, Standard for Electrical Safety in the Workplace, 2012 edition

1.3.4 OSHA 29 CFR 1910.7, Definition and requirements for a nationally recognized testing laboratory

1.3.5 OSHA 29 CFR 1910.132, Personal Protective Equipment

1.3.6 OSHA 29 CFR 1910.137, Electrical protective devices

1.3.7 OSHA 29 CFR 1910 Subpart S (.301-.399), Electrical (General Industry)

1.3.8 OSHA 29 CFR 1926 Subpart K (.400-.449), Electrical (Construction)

1.3.9 OSHA 29 CFR 1910.269, Electric Power Generation, Transmission, and Distribution

1.4 Format

1.4.1 The Electrical Safety Manual is divided into three Parts:

a. Part I: Electrical Hazards

b. Part II: Electrical Safe Work Practices

c. Part III: Acronyms, Definitions and Appendices

1.4.2 While most of this manual is written for people with an electrical background, Section 5, General Electrical Safety for All Persons, is written with the non-QEW in mind. Should the reader require help in understanding any part of this manual, contact an Electrical Safety Advocate, an Electrical Safety Officer, or the EHS Electrical Safety Group for assistance. You can also direct any questions to electricalsafety@lbl.gov.

1.4.3 For more information, including field guides and other useful tools for implementing this manual, go to http://electricalsafety.lbl.gov.

mailto:electricalsafety@lbl.gov http://electricalsafety.lbl.gov/

PART I – ELECTRICAL HAZARDS

2 Electrical Hazards

2.1 Scope

2.1.1 There are numerous injury mechanisms from exposure of a worker to electrical energy. This section, extracted from the DOE Electrical Safety Handbook, briefly presents the various types of electrical hazards, injuries that can result from those hazards, and a classification system with thresholds to trigger various controls.

2.2 Electrical Shock

2.2.1 Electricity is one of the most commonly encountered hazards in any facility. Under normal conditions, safety features (engineering controls) built into electrical equipment protect workers from shock. Shock is the flow of electrical current through any portion of the worker’s body from an external source.

Accidents can occur in which contact with electricity results in serious injury or death.

2.2.2 Most electrical systems establish a voltage reference point by connecting a portion of the system to an earth ground. Because these systems use conductors that have electrical potential (voltage) with respect to ground, a shock hazard exists for workers who are in contact with the earth and exposed to the conductors. If a person comes in contact with an energized (ungrounded) conductor, while also in contact with a grounded object, an alternate path to ground is formed in which current passes through his or her body.

2.2.3 The effects of electric current on the human body depend on many variables, including the:

a. Amount of current

b. Waveform of the current (e.g., DC, 60 Hz AC, RF, impulse)

c. Current’s pathway through the body (determined by contact location and internal body chemistry)

d. Duration of shock

e. Energy deposited into the body

2.2.4 The amount of current passing through the body depends on:

a. Voltage driving the current through the body

b. Circuit characteristics (impedance, stored electrical energy)

c. Frequency of the current

d. Contact resistance and internal resistance of the body

e. Environmental conditions affecting the body’s contact resistance

2.2.5 The heart and brain are the parts of the body most vulnerable to electric shock. Some research shows that fatal ventricular fibrillation (disruption of the heart’s rhythmic pumping action) can be initiated by a current flow of as little as 70 milliamperes (mA). Without immediate emergency resuscitation, electrical shock may cause a fatality from direct paralysis of the respiratory system, disruption of rhythmic pumping action, or immediate heart stoppage. Severe injuries, such as deep internal burns, can occur, even if the current does not pass through vital organs or the central nervous system. Specific values for hazardous voltages and for hazardous current flow through the body are not completely reliable because of physiological differences between people.

Condition Resistance (Ohms)

Dry Wet

Finger touch 40,000 to 1,000,000 4,000 to 15,000

Hand holding wire 15,000 to 50,000 3,000 to 6,000

Finger-thumb grasp 10,000 to 30,000 2,000 to 5,000

Hand holding pliers 5,000 to 10,000 1,000 to 3,000

Palm touch 3,000 to 8,000 1,000 to 2,000

Hand around 1.5 in pipe or drill handle 1,000 to 3,000 500 to 1,500

Two hands around 1.5 in pipe 500 to 1,500 250 to 750

Hand immersed - 200 to 500

Foot immersed - 100 to 300

Human body, internal, excluding skin ohms 200 to 1,000

Table 2.2.4a – Human resistance values for various skin-contact conditions1

1 Source: IEEE Std 3007.3-2012 Recommended Practice for Electrical Safety in Industrial and Commercial Power Systems

Material Resistance (Ohms)

Rubber gloves or soles >20,000,000

Dry concrete above grade 1,000,000 to 5,000,000

Dry concrete on grade 200,000 to 1,000,000

Leather sole, dry, including foot 100,000 to 500,000

Leather sole, damp, including foot 5,000 to 20,000

Wet concrete on grade 1,000 to 5,000

Table 2.2.4b – Resistance values for 130 cm2 areas of various materials2

Current (60 Hz) Physiological phenomena Feeling or lethality

<1.0 mA None Imperceptible

1.0 mA Perception threshold -

0.5 mA – 2.0 mA - Mild sensation

1.0 mA – 4.0 mA - Painful sensation

6.0 mA – 22 mA Paralysis threshold of arms Cannot release hand grip. If no grip, victim may be thrown clear. (May progress to higher current and be fatal.)

18 mA – 30 mA Respiratory paralysis Stoppage of breathing (frequently fatal).

90 mA Fibrillation threshold, 0.5% (greater than or equal to 3 sec exposure)

Heart action discoordinated (probably fatal).

2 Source: IEEE Std 3007.3-2012 Recommended Practice for Electrical Safety in Industrial and Commercial Power Systems

250 mA Fibrillation threshold, 99.5% (greater than or equal to 3 sec exposure)

Heart action discoordinated (probably fatal).

4 A Heart paralysis threshold (no fibrillation) Heart stops for duration of current passage. For short shocks, heart may restart on interruption of current (usually not fatal from heart dysfunction).

> 5 A Tissue burning Not fatal unless vital organs are burned.

Table 2.2.5 – Current Range and Effect on a 150 lbs. Person3

2.2.6 There are five principal electrical waveforms of interest that cause various responses to electrical shock:

a. Alternating current (AC) power frequencies

b. Direct current (DC)

c. Sub radio frequencies (sub RF) 1 Hz – 3 kHz

d. Radio frequencies (RF) 3 kHz – 100 MHz

e. Impulse shock (such as from a capacitor circuit)

2.2.7 AC Response:

a. The most dangerous are AC power frequencies, typically 60 hertz (Hz). Exposure to current at these frequencies causes ventricular fibrillation at the lowest thresholds and causes severe contraction of the muscles with a possible no-let-go response.

3 Source: IEEE Std 3007.3-2012 Recommended Practice for Electrical Safety in Industrial and Commercial Power Systems

Fig 2.2.7 – Combined physiological response to the effects of resistance and voltage4

b. Radiofrequency waveforms (5 kilohertz (kHz) to 100 megahertz (MHz)) have decreasing neurological effects with increasing frequency, but energy deposited results in tissue burning.

2.2.8 DC Response:

a. Exposure to DC electric currents can also cause a muscle response at first contact and when releasing, as well as heart fatigue and failure at high enough current levels.

b. DC current through the body does not induce muscle paralysis and does not create the hazards of let-go threshold, respiratory paralysis or fibrillation at low currents.

c. Prolonged exposure to DC current in the body can be fatal because of cumulative internal tissue burning.

4 Source: IEEE Std 3007.3-2012 Recommended Practice for Electrical Safety in Industrial and Commercial Power Systems

2.2.9 Capacitor response:

a. Capacitors can impose an impulse shock on the body. The damage induced is related to the voltage, the total energy discharged, and the amount of time it takes to deposit that energy.

b. Fast discharges of high energy can induce fibrillation of the heart. However, at lower voltages, the skin surface and body resistance typically increase the discharge time significantly and reduce the hazard.

c. See more information on capacitor hazards in Section 15.3.

2.2.10 Body Resistance:

a. The resistance of the body is much less if the skin is punctured by a shock above the skin breakdown threshold (400 to 500 V). This allows higher current flow through the body, resulting in more damage. The amount and duration of current flow determines the severity of the reflex action, the amount of damage to the heart, and neurological and other tissue.

b. The internal body resistance is often modeled as 1000 Ohms but can be as low as 200 Ohms.

2.2.11 Reflex action:

a. Reflex action occurs when electric current causes a violent contraction of the muscles. Such contraction can result in violent recoil, resulting in falling from heights, recoiling into a nearby hazard, or violent muscle contractions resulting in broken bones, torn ligaments, or dislocated joints. Reflex action is enhanced by high-voltage shock as the energy can be delivered more quickly from higher instantaneous currents.

2.2.12 Let-Go Threshold:

a. The so called no-let-go response occurs when continuous shock current keeps the muscles violently contracting such that the victim is clutching the conductor without any ability to release. This only happens with AC waveforms.

2.2.13 Shock Thresholds:

a. Because of the effects of the waveform on the body’s response, the thresholds for acceptable shock vary, depending on the form of the electricity. Acceptable means that below these thresholds there is no injury, and above these thresholds there could be injury.

b. The thresholds are listed in Table 2.2.13 and are found embedded in the hazard classification charts in Sections 3.3-3.8. The threshold values are based on available research and theoretical data. The hazard class values reflect the consensus agreement of a task group that developed the process, based on the collective knowledge and experience. The values should not be considered absolute, but guidance when applying effective hazard analysis to a particular task.

Source Includes Thresholds Hazard Classes (see section 3)

AC 50-60 Hz nominal ≥ 50 V and ≥ 5 mA 1.2, 1.3, 1.4, 1.5

DC All ≥ 100 V and ≥ 40 mA 2.2c, 2.2d, 2.3, 2.4

Capacitors All ≥ 100 V and ≥ 10 J 3.2b, 3.2c, 3.3b, 3.3c, 3.3d, 3.4b, 3.4c

Batteries Lead-Acid and Lithium Ion

≥ 100 V Could be in any Class, 4.0, 4.1, 4.2, 4.3

Sub-RF 1 Hz to 3 kHz (excluding 50-60 Hz nominal)

≥ 50 V and ≥ 5 mA 6.2a, 6.2b, 6.2c, 6.3, 6.4

RF 3 kHz to 100 MHz A function of frequency 5.2a, 5.2b

Table 2.2.13 – Thresholds for defining shock hazards

c. Table notes:

• It is possible for a worker to be exposed to more than one shock hazard at any given location (e.g. multiple types of sources).

• There may be other electrical hazards below the above shock thresholds (e.g., a thermal burn hazard-see Table 2.3.5).

• Injuries may result from startle reactions due to contact with energized components, even though the source energy is too low to do physical damage, such as high-voltage/low-current circuits (e.g., Classes 2.1d and 3.1d).

• Shock and burn hazards from induced and contact RF currents become negligible above 100 MHz (but radiated hazards still exist).

2.3 Electrical Burn

2.3.1 Burns suffered in electrical accidents are of three basic types – electrical current burns, arc burns, and thermal contact burns. The cause of each type of burn is different, and prevention necessitates different controls.

2.3.2 Electrical Current Burns

a. In electrical current burns, tissue damage (whether skin-level or internal) occurs because the body is unable to dissipate the heat from the current flow.

b. Typically, electrical current burns are slow to heal. Such electrical burns result from shock currents, and thus adhering to the shock current thresholds in Table 2.2.13 should prevent electrical current burns.

2.3.3 Arc Flash Burns

a. Arc flash burns are caused by electric arcs and are similar to heat burns from high-temperature sources. Temperatures generated by electric arcs can melt nearby material, vaporize metal in close vicinity, and burn flesh and ignite clothing at distances of several meters, depending on the energy deposited into the arc. The arc can be a stable low-voltage arc, such as in an arc welder, or a short-circuit arc at higher voltage, resulting in an arc flash and/or arc blast. Such an expanding arc can ignite clothing and/or cause severe burns at a distance from inches to feet.

b. There are five types of arc flash:

• Arc in open air: this type of arc is mostly infrared radiation as opposed to plasma and typically occurs on power lines in front of the worker. The gases are expanding in relatively all directions equally at once like a sphere. These gases can ignite clothing and cause skin burns as can the infrared radiation. This is the least invasive arc but the most easily measured. It is used in all ASTM test setups to test arc-rated materials.

• Arc in a box: This type is much more dangerous than an arc in open air. With an arc in a box, all of the energy is concentrated in a focused path—usually straight out the doors where you will be standing. This is typical of nearly all arc flash events in industrial electrical equipment (MCC’s, panelboards, switchgear, meter sockets, etc.)

• Arc plasma convective flow: a sustained arc flash event can be driven by the magnetic forces on the plasma cloud, forcing it to travel to the busbar tips, in a direction away from the power source. At the tips it forcefully ejects plasma in a convective flow. This flow can be highly directional, and can also be redirected by bouncing off metal surfaces. The resulting convective flow can lead to very high thermal concentration of the incident energy at a farther distance as opposed to the uniform spread calculated in the arc in open air and the arc in a box scenarios. While the result can exceed the rating of arc flash PPE, it can also be countered by proper body positioning.

• High voltage skin surface tracking arc: a high voltage shock event can sometimes lead to a tracking arc, where the current flows along the surface or just above the skin instead of through the body. In this case there is no metal plasma effect, just the thermal infrared burn from the arc itself. However, this type of arc can propagate underneath the arc flash PPE and ignite flammable undergarments, leading to very serious whole body burns.

• Traveling arc: an arc is initiated on uninsulated lines or busbar and travels away from the source.

c. The arc flash boundary is defined to characterize the distance at which this injury mechanism is severe. Hazard classes that include arc flash hazards are shown in Table 2.3.3. The current values are the short circuit available currents, or fault currents. The threshold values are based on available research and theoretical data. The hazard class values reflect the consensus agreement of the task group that developed the process based on the collective knowledge and experience. The values should not be considered absolute, but, rather as guidance when applying effective hazard analysis to a particular task.

Source Includes Thresholds Hazard Classes (see section 3)

AC power 50-60 Hz nominal

<250 V and the transformer supplying the circuit is rated >125 kVA

<250 V and the circuit is supplied by more than one transformer

≥ 250 V

1.2, 1.3, 1.4, 1.5

Sub-RF 1 Hz to 3 kHz (excluding 50-60 Hz nominal)

≥ 250 V and ≥ 500 A 6.4

DC All ≥ 100 V and ≥ 500 A 2.4

Capacitors All ≥ 100 V and ≥ 10 kJ 3.4b, 3.4d

Batteries All ≥ 100 V and ≥ 500 A 4.3

RF NA NA

Table 2.3.3 – Thresholds for defining arc flash hazards

2.3.4 Arc Blast Hazards

a. A rapid delivery of electrical energy into an arc can cause additional hazards not covered by arc flash hazards. The acoustical shock wave, or arc blast pressure wave, can burst eardrums at lower levels and can cause cardiac arrest at high enough levels.

b. In addition, high currents (> 100 kA) can cause strong magnetic forces on current-carrying conductors, which can lead to equipment destruction, or the whipping of conductors. Such arc blast hazards are of particular concern in high-energy facility power circuits (Classes 1.3d, 1.4, and 1.5) and large capacitor banks (Class 3.4d).

2.3.5 Thermal Contact Burns

a. Thermal contact burns are those that occur when skin comes into contact with the hot surfaces of overheated electrical conductors, including conductive tools and jewelry. This injury results from close proximity to a high-current source with a conductive object.

b. Thermal burns can occur from low-voltage/high-current systems that do not present shock or arc flash hazards, and controls should be considered. The controls to prevent injury from shock and arc flash should also protect against thermal contact burn.

c. High-current hazard classes with thermal burn hazards are shown in Table 2.3.5. The threshold values are based on available research and theoretical data. The values are calculated to raise the temperature of the skin to a level that would cause a second-degree burn using the Stoll Curve at a time of two seconds. The hazard class values reflect the consensus agreement of the task group that developed the process based on the collective knowledge and experience. The values should not be considered absolute, but guidance when applying effective hazard analysis to a particular task.

Source Includes Thresholds Hazard Classes (see section 3)

Sub-RF 1 Hz to 3 kHz (excluding 50-60 Hz nominal)

<50 V and >1000 W 6.2a

DC All >100 V and >1000 W 2.2a, 2.2b

Capacitors All <100 V and >100 J 3.2a, 3.3a, 3.4a

Batteries All <100 V and >1000 W 4.2, 4.3

RF NA NA NA

Table 2.3.5 – Thermal contact burn hazards, not included in shock and arc flash hazards

2.4 Delayed Effects

2.4.1 Damage to the internal tissues may not be apparent immediately after contact with electrical current.

Delayed swelling and irritation of internal tissues are possible. In addition, imperceptible heart arrhythmia can progress to ventricular fibrillation.

2.4.2 In some cases, workers have died two to four hours after what appeared to be a mild electrical shock.

Immediate medical attention may prevent death or minimize permanent injury. All electrical shocks should be reported immediately.

2.5 Battery Hazards

2.5.1 During maintenance or other work on batteries and battery banks, there are electrical and physical hazards that should be considered. In addition, when working near or on flooded lead-acid storage batteries additional chemical and explosion hazards should be considered.

2.5.2 The hazards associated with various types of batteries and battery banks include:

a. Electric shock;

b. Burns and shrapnel-related injuries from a short circuit;

c. Chemical burns from electrolyte spills or from battery surface contamination;

d. Fire or explosion due to hydrogen;

e. Physical injury from lifting or handling the cells; or

f. Fire from overheated electrical components.

2.6 Other Hazards

2.6.1 Low-Voltage Circuits

a. Low-voltage circuits, which are not hazardous themselves, are frequently used adjacent to hazardous circuits. A minor shock can cause a worker to rebound into the hazardous circuit.

b. Such an involuntary reaction may also result in bruises, bone fractures, and even death from collisions or falls. The hazard is due to the secondary effects of the reflex action.

2.6.2 Operating Electrical Disconnects

a. An arc may form when a short circuit occurs between two conductors of differing potential, or when two conductors carrying current are separated, such as a safety switch attempting to interrupt the current. If the current involved is high enough, the arc can cause injury, ignite flammable materials or initiate an explosion in combustible or explosive atmospheres.

b. Injury to personnel can result from the arc flash, or arc blast, resulting in severe burns to exposed skin, or ignition of clothing. Equipment or conductors that overheat, due to overload, may ignite flammable materials. Extremely high-energy arcs can cause an arc blast that sends shrapnel flying in all directions.

2.6.3 R&D Electrical Equipment

a. Analyzing electrical hazards associated with R&D equipment may present challenges beyond that associated with standard electrical distribution equipment. Some R&D equipment is custom designed and built and may need specific qualifications for workers that operate or maintain the equipment. An uncommon or unique design can be difficult to analyze for hazard identification.

b. Regardless, the hazard analysis should include shock, potential arc or thermal sources. Acoustic shock wave, pressure shock wave and shrapnel are potential hazards that should be considered as well. Once the hazards have been identified, a risk mitigation plan should be developed.

c. Personnel working on electrical equipment should be specifically qualified through training specific to the work to be done. The scope of such additional training depends on the hazards associated with the equipment.

3 Electrical Hazard Classification

3.1 Explanation of the electrical hazard classification structure

3.1.1 The electrical hazard classification charts cover eight broad categories: 50-60 Hz, DC, capacitors, batteries, Sub-RF, RF, inductors, and photovoltaic. Table 3.2 shows these eight major categories with a pointer to the figure where each category is broken into the individual classes. These classes, taken collectively, represent the electrical hazards found in electrical equipment.

3.1.2 All classes should be considered when identifying the hazards associated with any piece of electrical equipment. A single piece of equipment may have multiple electrical hazard classifications, and the combination of hazards must be addressed by appropriate safety-related work practices.

3.1.3 To aid hazard identification, each chart has cross-reference notes in the upper right hand corner. For example, the DC chart has cross-reference notes to capacitance, inductance, Sub-RF, battery, and 50- 60 Hz hazard charts. Workers shall have a thorough understanding of the equipment they are analyzing for hazards. Consulting manuals and schematics and speaking with factory service representatives and electrical SMEs are ways to ensure that all of the hazards are fully understood and that all the pertinent classes are taken into account.

3.1.4 Some guidelines on use of the hazard classification charts are provided, below. They are general, and there may be exceptions to each one:

a. If these guidelines and the equipment are not understood, an SME should be consulted.

b. All equipment gets its power from 50-60 Hz (Classes 1.x) or batteries (Classes 4.x). Thus, all equipment starts with one of those classes.

c. Most small appliances, hand tools, and portable laboratory equipment plugs into Class 1.2. In general, if it can be carried, it most likely it uses 120 to 240 V.

d. Larger facility and laboratory equipment may use up to 480 V (Class 1.3). Often, if it is a large motor, or consumes significant power, it may be Class 1.3.

e. DC power supplies need to be evaluated for both DC (Class 2.x) and Capacitance (Class 3.x).

f. All UPSs have hazards in Classes 4.x as well as 1.x, since they usually are tied into facility power (input), and produce facility type power (output).

3.1.5 The colors used in each hazard Class box are organized in increasing hazard: blue, green, yellow, red, and maroon. Some general statements can be made about each color. There may be exceptions.

Light blue and white boxes are not hazard classes, but are decision points.

A blue Class (X.0) indicates no hazard, and no engineering or administrative controls are needed.

A green Class (X.1) indicates little to no hazards, few, or no, engineering or administrative controls are needed.

A yellow Class (X.2) indicates injury or death could occur by close proximity or contact; often the hazard is shock or contact burn. Engineering controls are necessary for operation (e.g., listing or equipment approval), and administrative controls are necessary for electrical work in this Class.

A red Class (X.3) indicates injury or death could occur by proximity or contact; often the hazard is shock, contact burn, or arc-flash burn; engineering controls are necessary for operation (e.g., listing or equipment approval), and administrative controls are necessary for electrical work in this Class.

Maroon Class (X.4 and X.5) is the highest level of risk; significant engineering and administrative controls are necessary to manage the hazard in these classes.

Gray, Class 3.1c, takes the user outside of electrical safety controls, as the primary hazard is chemical explosion.

3.1.6 Modes of work (for a description of Modes of work, see 6.4-6.7):

a. Mode 0 – Electrically Safe Work Condition

b. Mode 1 – Establishing an Electrically Safe Work Condition

c. Mode 2 – Energized Diagnostics (Testing & Troubleshooting)

d. Mode 3 – Energized Repair Work (EEWP)

3.2 Classification Matrix

Class 1.x Class 2.x Class 3.x Class 4.x Class 5.x Class 6.x Class 7.x Class 8.x

50-60 Hz Power

DC Capacitors Batteries RF Sub-RF Inductors Photovoltaic Cells

See Fig. 3.3 See Fig. 3.4 See Fig.

3.5.a-b

See Fig. 3.6 See Fig. 3.7 See Fig. 3.8 future updates future updates

Table 3.2 – Complete Electrical Hazard Classification System Showing Eight Major Classes

Class 1.x 60 Hz Power

Class 2.x

DC

Class 3.x Capacitors

Class 4.x Batteries

Class 5.x

RF

Class 6.x Sub-RF

Class 7.x Inductors

Class 8.x Photovoltaic Cells

Choose the source(s) of energy

3.3 Hazard Class 1.x, 50-60 Hz Nominal Power

Fig. 3.3. Hazard Classes 1.x, for 50-60 Hz Nominal Power

Notes on use:

1. The voltage is the root mean square (rms) voltage.

2. For current limited 50-60 Hz circuits (≤5 mA), use hazard Class 6.x, Sub-RF.

Determine the voltage

Class 1.0 < 15 V

Class 1.1 15 – 50 V

208 – 300 V Class 1.3b

300 – 750V

Determine if there is an arc flash hazard

Class 1.3a with arc flash hazard

Class 1.2b without arc flash hazard

Class 1.4 > 750V

Class 1.2a 50 – 120 V

Single Phase

Table 3.3. Control Table for Work in Hazard Classes 1.x, 50-60 Hz AC Nominal Power Class Mode Two-Person QEW Level Work Control PPE 1.0

<15 V

All Alone Non-QEW None None

1.1

15–50 V

All Alone Non-QEW None None

1.2a

50–120 V Single Phase

0 Alone QEW 1 LOTO Minimum PPE 1 Alone LOTO Shock PPE 2 Standby Person Barricade 3 Safety Watch EEWP

1.2b 208–300 V 3-Phase without arc flash hazard

0 Alone QEW 1 LOTO Minimum PPE 1 Alone LOTO Shock PPE 2 Standby Person Barricade 3 Safety Watch EEWP

1.3a 3-Phase 208–300 V with arc flash hazard

0 Alone QEW 2 LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Arc Flash PPE 2 Safety Watch Barricade 3 Safety Watch EEWP

1.3b 3-Phase 301–750 V

0 Alone QEW 2 LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Arc Flash PPE

2 Safety Watch Barricade 3 Safety Watch EEWP

1.4 3-Phase >750 V

0 Alone QEW 3 LOTO Minimum PPE 1 Standby Person LOTO, ESWP Shock PPE, Arc Flash PPE 2 Safety Watch ESWP 3 Safety Watch EEWP

Notes:

1) Mode 2 in Class 1.2 may be performed alone, if proper voltage rated gloves and leather protectors are worn.

2) Non-hazardous switching (see 6.3.6.c and 8.2.5.b exception) for Mode 1 in Class 1.3 may be performed alone. However, the standby person is required for ZVV.

3) Minimum PPE is non-melting clothing (long sleeve shirt and pants) and safety glasses (Section 10.1)

4) Shock PPE is determined by performing a shock hazard analysis using methods covered in Section 7.1.

5) Arc Flash PPE is determined by performing an arc flash hazard analysis using methods covered in Section 8.1.

3.4 Hazard Class 2.x, DC

Fig. 3.4 Hazard Classes 2.x, DC

1. The voltage is the DC voltage.

2. Power is available short-circuit power.

3. Current is available short-circuit current.

4. Most equipment supplying DC also needs to be evaluated for capacitance hazards in Class 3.x.

Determine the voltage

< 15 V

Determine the Power

15 – 99 V

Determine the Power

100 – 399 V

Determine the Power

≥ 400 V

Determine the Power

Class 2.0 < 100 W

Class 2.1a 100 – 999 W

Class 2.2a

≥ 1000 W

Class 2.1b < 1000 W

Class 2.2b

≥ 1000 W

Class 2.1c < 40 mA

Class 2.2c 40 mA – 499 A

Class 2.3a

≥ 500 A

Class 2.2d 40mA-199 mA

Class 2.3b 200 mA–499A

Class 2.4

≥ 500 A Class 2.1d < 40 mA

Table 3.4. Control Table for Work in Hazard Classes 2.x, DC

2.0

≤15 V, ≤100 W

All Alone Non-QEW None None

2.1a,b,c,d

≤100 V, ≤1 kW or >100 V, ≤40 mA

All Alone Non-QEW

None None

2.2a

≤15 V >1 kW

All Alone Non-QEW

None None

2.2b

15–100 V >1 kW

All Alone Non-QEW None None

2.2c

100–400 V 40 mA–500 A

0 Alone QEW R LOTO Minimum PPE 1 Alone LOTO Shock PPE 2 Standby Person Barricade 3 Safety Watch EEWP

2.2d

>400 V 40–200 mA

0 Alone QEW R LOTO Minimum PPE 1 Alone LOTO Shock PPE 2 Standby Person Barricade 3 Safety Watch EEWP

2.3a

100–400 V >500 A

0 Alone QEW 1, QEW 2 if arc flash hazard

LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Arc Flash PPE 2 Safety Watch Barricade 3 Safety Watch EEWP

2.3b

>400 V 200 mA–500 A

0 Alone QEW 2 LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Arc Flash PPE 2 Safety Watch Barricade 3 Safety Watch EEWP

2.4

>400 V >500 A

0 Alone QEW 2 LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Arc Flash PPE 2 Safety Watch Barricade 3 Safety Watch EEWP

Notes:

1) Minimum PPE is non-melting clothing (long sleeve shirt and pants) and safety glasses (Section 10.1)

2) Shock PPE is determined by performing a shock hazard analysis using methods covered in Section 7.1.

3) Arc Flash PPE is determined by performing an arc flash hazard analysis using methods covered in Section 8.1.

3.5 Hazard Class 3.x, Capacitors

Fig. 3.5a – Hazard Classes 3.x, Capacitors, <400 V

1. Voltage is peak of the AC, peak impulse or DC maximum charge voltage on the capacitor.

2. Energy is maximum energy stored in the capacitor as determined by E = ½ CV2.

3. The hazards for less than 100 V, Classes 3.2a, 3.3a, 3.4a, are high current through a short circuit, such as tools and jewelry.

4. The hazards for 100 – 399 V, Classes 3.2b, 3.3b, 3.4b, are high current through a short circuit, and a shock hazard.

5. Class 3.4b has an added hazard of mechanical damage due to high currents and strong pulsed magnetic forces during a short circuit.

< 100 V

Determine the Energy

E = ½ CV2

Class 3.1a < 100 J

Class 3.2a 100 – 999 J

Class 3.3a 1 kJ – 9.9 kJ

Class 3.2b 10 J – 99 J

Class 3.3b 100 J – 9.9 kJ

Class 3.4b ≥ 10 kJ

Class 3.1b < 10 J

Class 3.4a ≥ 10 kJ

100 – 399 V

Determine the Energy

E = ½ CV2

Table 3.5a. Control Table for Work in Hazard Classes 3.x, Capacitors (< 400 V) Class Mode Two-Person QEW Level Work Control PPE Stored Energy Removal

3.1a

< 100 V < 100 J

All Alone Non-QEW None None

3.1b

100 – 399 V < 10 J

All Alone Non-QEW None None

3.2a

< 100 V 100 J – 999 J

All Alone Non-QEW Capacitor Safety

WPC

Safety glasses

3.2b

100 – 399 V 10 –99 J

0 Alone QEW R + Capacitor Safety

LOTO Minimum PPE 1 Alone LOTO Shock PPE

2 Standby Person Barricade Shock PPE 3 Standby Person EEWP Shock PPE

3.3a

< 100 V 1 kJ –9.9 kJ

0 Alone

Non-QEW Capacitor Safety

WPC

Safety glasses

1 Soft Ground Hook >1 kJ

3.3b

100 – 399 V 100 J –9.9 kJ

0 Alone QEW R + Capacitor Safety

LOTO Minimum PPE 1 Standby Person LOTO Shock PPE Soft Ground Hook >1 kJ 2 Safety Watch Barricade Shock PPE 3 Safety Watch EEWP Shock PPE

3.4a

<100 V ≥ 10 kJ

0 Alone

Non-QEW Capacitor Safety

WPC Minimum PPE 1 Minimum PPE Remote soft grounding 2 Minimum PPE Remote testing 3 Minimum PPE

3.4b

100 – 399 V ≥ 10 kJ

0 Alone QEW R + Capacitor Safety

QEW 2 +

Capacitor Safety if arc flash hazard

LOTO None 1 Standby Person LOTO Shock PPE, Arc Flash

PPE

Remote soft grounding

2 Safety Watch Barricade Shock PPE, Arc Flash

PPE

Remote testing

3 Safety Watch Barricade, EEWP

Shock PPE, Arc Flash

PPE

Notes:

1) Minimum PPE is non-melting clothing (long sleeve shirt and pants) and safety glasses (Section 10.1)

2) Shock PPE is determined by performing a shock hazard analysis using methods covered in Section 7.1.

3) Arc Flash PPE is determined by performing an arc flash hazard analysis using methods covered in Section 8.1.

4) Column ‘Stored Energy Removal’ is the method used to discharge lower-energy capacitors, or apply a safety ground on higher-energy capacitors.

5) “Remote soft grounding” means using engineering methods to discharge and verify the capacitors without worker exposure (e.g., a capacitor remote “dump” or discharge system).

6) “Remote testing” means using sensors and instruments that are placed during a Mode 0 condition, then observed from a safe location during Mode 2 work.

Fig. 3.5b. Hazard Classes 3.x, Capacitors, >400 V

1. Voltage is peak of the AC, peak impulse or DC maximum charge voltage on the capacitor.

2. Energy is maximum energy stored in the capacitor as determined by E = ½ CV2.

3. The hazards for greater than 400 V, Classes 3.2c, 3.3c, 3.3d, 3.4c are high current through a short circuit, and a shock hazard with a strong reflex action for Class 3.2c, and serious tissue injury and/or death for 3.3c and above.

4. Class 3.3d and 3.4c have the added hazards of mechanical damage due to high currents and strong pulse magnetic forces during a short circuit.

5. For Class 3.1c, the hazard is not electrical; refer to an explosive or hazardous location SME to manage the hazard.

ESD

the Location

Class 3.0 Non-Hazardous

Location

Class 3.1c Hazardous Location

Class 3.3c 50 J – 999 J

Class 3.3d 1 kJ – 9.9 kJ

Class 3.4c ≥ 10 kJ

Class 3.2c 10 J – 49 J

Class 3.1d < 10 J

Capacitor

Determine the Energy

E = ½ CV2

≥ 400 V the Source

Table 3.5b. Control Table for Work in Hazard Classes 3.x, Capacitors (≥ 400 V)

Stored Energy

Removal 3.0–ESD All Alone Non-QEW None None None 3.1d

≥ 400 V < 10 J

All Alone Non-QEW None None Hard ground

3.2c

≥ 400 V 10 J – 49 J

0 Alone QEW R + Capacitor Safety

LOTO Minimum PPE 1 Alone LOTO Shock PPE Hard ground 2 Standby Person Barricade Shock PPE 3 Safety Watch EEWP Shock PPE

3.3c

≥ 400 V 50 J – 999 J

0 Alone QEW R + Capacitor Safety

LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Hearing Protection

Hard ground

2 Safety Watch Barricade Shock PPE, Hearing Protection

3 DO NOT do this mode of work.

3.3d

≥ 400 V 1 kJ –9.9 kJ

0 Alone QEW R + Capacitor Safety

LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Hearing Protection

Soft Ground

2 Safety Watch Barricade Shock PPE, Hearing Protection

3 DO NOT do this mode of work.

3.4c

≥ 400 V ≥ 10 kJ

0 Alone QEW 2 + Capacitor Safety

LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Arc

Flash PPE, Hearing Protection

Remote soft grounding

2 Safety Watch Barricade Shock PPE, Arc Flash PPE, Hearing Protection

Remote testing

3 DO NOT do this mode of work.

Notes:

1) Minimum PPE is non-melting clothing (long sleeve shirt and pants) and safety glasses (Section 10.1)

2) Shock PPE is determined by performing a shock hazard analysis using methods covered in Section 7.1.

3) Arc Flash PPE is determined by performing an arc flash hazard analysis using methods covered in Section 8.1.

4) Column ‘Stored Energy Removal’ is the method used to discharge lower-energy capacitors, or apply a safety ground on higher-energy capacitors.

5) “Remote soft grounding” means using engineering methods to discharge and verify the capacitors without worker exposure (e.g., a capacitor remote “dump” or discharge system).

6) ”Remote testing” means using sensors and instruments that are placed during a Mode 0 condition, then observed from a safe location during Mode 2 work.

3.6 Hazard Class 4.x, Batteries <100 VDC

Fig. 3.6. Hazard Classes 4.x, Batteries and Battery Banks <100 VDC

1. For battery systems ≥ 100 VDC, use hazard Classes 2.x to categorize the shock hazard.

2. Power is the short circuit available power from the battery.

3. There can be no Mode 0 or 1 for batteries, as they are always energized.

4. Additional PPE is necessary for vented lead-acid batteries, depending on the work activity (e.g., chemical

PPE).

5. Although all work on Class 4.2 (e.g., automotive batteries) is Energized Work, some of this work (e.g. jump starting cars) is commonly done by the public. Caution should be used, however, and appropriate training and controls in place.

6. Some class 4.2 batteries (e.g., desktop UPS batteries) may have adequate engineering controls, such as recessed terminals, to reduce the need for administrative controls.

7. For batteries and battery systems other than Lead Acid and Lithium Ion, use hazard Classes 2.x to categorize the shock hazard.

the Chemistry

Lead Acid

Determine the Power

Class 4.1b Commercial, using supplied charger per manufacturer’s instructions

Class 4.2b Single Cell

Class 4.3b Multi Cell

Class 4.0 ≤ 100 W

Class 4.1a 100 – 1000 W

Class 4.2a 1 – 30 kW

Class 4.3a > 30 kW

Lithium Ion

The Type

Table 3.6a. Control Table for Work in Hazard Classes 4.xa, Batteries (Lead Acid) <100 VDC

4.0

<100 W

All Alone Non-QEW None None

4.1a

100–1000 W

All Alone Non-QEW None No Jewelry

4.2a

1–30 kW

2 Alone Non-QEW YES Eye, No Jewelry

3 Alone Non-QEW YES Eye, No Jewelry

4.3a

>30 kW

2 Alone Non-QEW YES Eye, No Jewelry

3 Alone Non-QEW YES Eye, No Jewelry, Special Battery Tools

Notes on use:

1 For greater than 100 VDC, use hazard Classes 2.x to categorize the shock hazard.

2 For battery banks greater than 100 VDC, break up bank for energized work, when possible.

Table 3.6b. Control Table for Work in Hazard Classes 4.xb, Batteries (Lithium Ion) <100 VDC

Class Mode Two-Person QEW Level Work Control Additional Controls

4.1b

Commercial

While Charging

Alone Non-QEW Charge per manufacturer’s instructions using the supplied charger.

None

4.2b1

Single Cell

While Charging

Alone Non-QEW YES None

4.3b1

Multi Cell

While Charging

Alone Non-QEW YES Containment, monitor temp using thermocouples

1 Ensure, through AHJ equipment approval that the batteries and battery packs have integral protection and that the charging circuit is matched to the battery or battery pack.

Notes on use:

1. For greater than 100 VDC, use hazard Classes 2.x to categorize the shock hazard.

2. For battery banks greater than 100 VDC, break up bank for energized work, when possible.

3.7 Hazard Class 5.x, RF Circuits (3 kHz to 100 MHz)

Fig. 3.7. Hazard Classes 5.x, RF Circuits 3 kHz to 100 MHz (f is in MHz)

1. “f” in the Chart is frequency in MHz. “1000f mA” means 1000 times the frequency in MHz. For example, if the frequency is 18 kHz, the shock current threshold is 0.018x1000 = 18 mA.

2. Classes 5.x only address the RF shock hazard. They do NOT address the exposure to electromagnetic fields. PUB-3000 Chapter 44, Non-Ionizing Radiation covers the exposure to electromagnetic fields.

3. The RF hazard classification chart in Fig. 3.7 determines if the RF source can put out sufficient current to be a shock/burn hazard. However, it does not take into account the body impedance, which is necessary to determine if the source can drive these currents into the body. The tools for body impedance modeling are too detailed to put into this document.

4. Types of waveforms and other factors that are not included in this table will need to be evaluated by competent persons for all hazards.

Determine the Frequency

3 kHz – 99 kHz

Determine the Current

Class 5.1b < 100 mA

Class 5.2b

≥ 100 mA Class 5.1a

< 1000f mA Class 5.2a

≥ 1000f mA

0.1 – 100 MHz

Determine the Current http://www2.lbl.gov/ehs/pub3000/CH43.html

Table 3.7. Control Table for Work in Classes 5.x, RF Circuits (3 kHz to 100 MHz)

Class Mode Two-Person QEW Level Work Control PPE

5.1a

0.003–0.1 MHz <1000f mA

All Alone Non-QEW None None

5.1b

0.1–100 MHz <100 mA

All Alone Non-QEW None None

5.2a

0.003–0.1 MHz ≥1000f mA

All

Alone

QEW 1

Must perform RF hazard analysis based on PUB-3000 Chapter 44, Non-Ionizing Radiation.

5.2b

0.1–100 MHz ≥100 mA

All

Alone QEW 1

3.8 Hazard Class 6.x, Sub-RF Circuits (1 Hz to 3 kHz)

Fig. 3.8. Hazard Classes 6.x, Sub-RF Circuits (1 Hz to 3 kHz)

1. This hazard class is not to be used for 50-60 Hz power, except for power limited 50-60 Hz circuits that cannot have currents over 5 mA.

2. Power is available short-circuit power.

3. Current is available short-circuit current.

the Voltage

≤ 50 V

Determine the Power

> 250 V

Determine the Current

Class 6.1a ≤ 1000 W

Class 6.2a > 1000 W

Class 6.1c ≤ 5 mA

Class 6.4 > 500 A

Class 6.3 75 mA – 500 mA

Class 6.2c 5 – 75 mA

Class 6.1b ≤ 5 mA

Class 6.2b > 5 mA

50 – 250 V the Current

Table 3.8. Control Table for Work in Classes 6.x, Sub-RF Circuits (1 Hz to 3 kHz)

6.1a,b,c ≤50 V, ≤1 kW or >50 V, ≤5 mA

All Alone Non-QEW None None

6.2a ≤50 V >1 kW

All Alone Non-QEW None None

6.2b 50–250 V >5 mA

0 Alone QEW 1 LOTO Minimum PPE 1 Alone LOTO Shock PPE 2 Standby Person Barricade Shock PPE 3 Safety Watch EEWP Shock PPE

6.2c >250 V 5–75 mA

0 Alone QEW 1 LOTO Minimum PPE 1 Alone LOTO Shock PPE 2 Standby Person Barricade Shock PPE 3 Safety Watch EEWP Shock PPE

6.3 >250 V 75 mA–500 A

0 Alone QEW 2 LOTO Minimum PPE 1 Standby Person LOTO Shock PPE 2 Safety Watch Barricade Shock PPE 3 Safety Watch EEWP Shock PPE

6.4 >250 V >500 A

0 Alone QEW 2

LOTO Minimum PPE 1 Standby Person LOTO Shock PPE, Arc Flash

PPE

2 Safety Watch Barricade Shock PPE, Arc Flash

PPE

3 Safety Watch EEWP Shock PPE, Arc Flash

PPE

Notes:

1) Minimum PPE is non-melting clothing (long sleeve shirt and pants) and safety glasses (Section 10.1)

2) Shock PPE is determined by performing a shock hazard analysis using methods covered in Section 7.1.

3) Arc Flash PPE is determined by performing an arc flash hazard analysis using methods covered in Section 8.1.

PART II – ELECTRICAL SAFE WORK PRACTICES

4 Electrical Safety Principles & Controls

4.1 Principles of Electrical Safety

4.1.1 Electricity is different from other forms of hazardous energy, because it is both undetectable by human senses and potentially immediately fatal upon contact.