Electrical Standards MODULE 10. 2©2006 TEEX Hazard Brainstorming Where are electrical hazards on oil and gas well sites?

Electrical StandardsMODULE 10

2 ©2006 TEEX

Hazard Brainstorming

Where are electrical hazards on oil and gas well sites?

3 ©2006 TEEX

Statistics

Electrocution: Among most frequent causes of occupational injury death in US

295 fatalities/year; 4309 lost time 1992-2002: 9% decrease Most frequent cause: Overhead power

lines

4 ©2006 TEEX

Factors in Fatal Electrocutions

Safe work practices implemented and followed?

Adequate/required PPE provided and worn? Lockout/tagout procedures implemented and

followed? OSHA, NEC, NESC compliance? Worker and supervisor training adequate? (from NIOSH)

5 ©2006 TEEX

Types of Electrical Injuries

Electrocution (death due to electrical shock)

Electrical shock Burns (ugly pictures here) Falls

6 ©2006 TEEX

Hazard Recognition

How can you sense electrical danger? Cannot see, smell, taste, or hear danger Can recognize unsafe conditions

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Electrical Terminology

Current – movement of electrical charge Resistance – opposition to current flow Voltage – measure of electrical force Conductors – substances with little

resistance to electricity (such as metals) Insulators – substances with high resistance

to electricity (such as wood, rubber, glass, & bakelite)

Grounding – a conductive connection to the earth (which acts as a protective measure)

8 ©2006 TEEX

Electrical Shock

Received when current passes through body

Severity depends on: Path of current through body Amount of current flowing through body Length of time body is in circuit Also: voltage, moisture, heart cycle, health

Low voltage is NOT low hazard!

9 ©2006 TEEX

Dangers of Electrical Shock

Currents >75 mA* can cause ventricular fibrillation (rapid, ineffective heartbeat) mA = milliampere = 1/1,000 of an ampere Death within minutes unless a defibrillator

is used 75 mA is not much current

(a small power drill uses 30 times as much)

10 ©2006 TEEX

Effects of Current on Body

1 mA: Perception level, slight tingling. 5 mA: Slight shock; not painful.

Can usually let go. Involuntary reactions can cause injuries.

6-30 mA: Painful shock Muscular control lost Freezing current or “let-go” range

11 ©2006 TEEX

Effects of Current on Body

50-150 mA: Extreme pain Respiratory arrest; cannot let go Death possible

1000-4300 mA: Ventricular fibrillation Muscular contraction; nerve damage Death likely

10000 mA: Cardiac arrest Severe burns, probable death

12 ©2006 TEEX

How Shock Happens

Connection between: 2 wires of energized circuit 1 wire of energized circuit and ground Metallic part in contact with energized wire

and ground

13 ©2006 TEEX

Inadequate Wiring Hazards

What happens when a wire is too small to carry the current safely? Overheating Risk of fire or short circuit Fuse acts as sacrificial

weak link Fuse too strong?

Other parts of the system break first

Wire Gauge

WIRE

14 ©2006 TEEX

29 CFR 1910 and 29 CFR 1926

1910 Subpart S = Electrical Revised 2/14/2007; effective in 180 days

1910 Subpart I = PPE 1910.137 Electrical Protective Devices

1926 Subpart K = Electrical Protect against recognized hazards

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Other Standards

NFPA 70E enacted to help meet CFR Revised Subpart S based heavily on 2000

version 2004 version now published OSHA chose which provisions of 70E to

adopt

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29 CFR 1910 Subpart S

Electrical standards for general industry § 302-308 and 399 updated: PM App. C 5 main groups of standards:

Design safety standards § 302-330 Safety-related work practices § 331-360 Reserved: maintenance, special equipment Definitions: § 399

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1910.302 Electric utilization systems (PM Appendix C)

Applicability of regulations By type of installation By installation date

General1903.303

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1910.303 (a) Approval

Conductors and equipment acceptable only if approved Note: If installation is made in accordance

with NEC or ANSI/NFPA it will be deemed in compliance.

See definitions

20 ©2006 TEEX

1910.303(b) Examination, installation, and use of equipment

Examination – shall be free of recognized hazards Suitability (check listing/labeling) Other factors listed in regulation

Installation and use – by instructions Insulation integrity Interrupting rating (fuses, breakers)

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Circuit impedance… Deteriorating agents – water, gases,

excessive temperature, corrosives… Mechanical execution of work

Close unused openings for protection Conductors racked for safe access Internal parts not contaminated No damaged parts

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Mounting and cooling Firmly secured Air circulation; clearance Ventilation openings not obstructed

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1910.303(c) Electrical connections

General – dissimilar metals Terminals – connections Splices – correctly performed, insulated

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1910.303(d) Arcing parts

Some electrical equipment normally produces arcs, sparks, flames, molten metal

Keep isolated from combustible material

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1910.303(e) Marking

Manufacturer and ratings must be marked Voltage, current, wattage, etc. Durable markings in environment

26 ©2006 TEEX

1910.303(f) Disconnecting means and circuits

Legibly marked to indicate purpose Unless purpose is evident

Durable Able to be locked open Series combination rating = special

marking

Subtitles & TransitionsFOR EXAMPLE…

Example of properly labeledelectric service: motors, disconnects and breakers

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1910.303(g) 600 Volts, nominal, or less

1. Space about electric equipment Space, not used for storage Guarded when parts exposed Entrances Illumination Headroom Control boards in dedicated, protected

space

29 ©2006 TEEX

1910.303(g) 600 Volts, nominal, or less

2. Guarding of live parts Live parts 50 volts protected from

people Protection from damage Warning signs for unqualified persons

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1910.303(h) Over 600 volts, nominal

2. Enclosure / access control

3. Work space about equipment

4. Entrance and access to work space

5. Working space and guarding

Wiring Design and Protection1903.304

32 ©2006 TEEX

1910.304(a) Use and identification of grounding conductors

1. Grounded & equipment grounding conductors identifiable & distinguishable

Grounded = white or gray Equipment grounding = green, or green

with yellow strips, or bare

2. Polarity may not be reversed3. Grounding devices not used for other

purposes

33 ©2006 TEEX

Polarity

Reversed polarity: Neutral (grounded) conductor connected to hot (ungrounded) terminal incorrectly

Most common on smaller branch circuits 120 V receptacle outlets Cord- and plug-connected

equipment



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1910.304(b) Branch circuits

1. Identification of multiwire branch circuits

For >1 voltage system in a building ID phase and system Permanently posted at each panelboard

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2. Receptacles and cord connectorsi. Grounding type for 15A & 20A circuits

Receptacles only on circuits matching voltage and current rating

ii. Grounding contacts grounded Except portable / vehicle-mounted generators Except replacement receptacles

iii. Grounding contact connected to equipment grounding conductor

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2. Receptacles and cord connectorsiv. Replacement of receptacles

Grounding-type where grounding means exists

GFCI where required Options for lack of grounding means

v. Plugs not interchangeable for different voltage, frequency, type of current

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3. Ground-fault circuit interrupter (GFCI)i. Bathroom or rooftops

ii. Temporary wiring: Including extension cords If unavailable for less-usual type of

receptacle: assured equipment grounding conductor program.

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4. Outlet devicesi. Heavy-duty lampholders for >20A

ii. Receptacle outlets: Receptacle ampere rating branch circuit For 2 outlets on branch circuit: Table S-4

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For 2 outlets on branch circuit: Table S-5 50 A: receptacle branch-circuit rating

5. Cord connections: Outlet where flexible cords with plugs used

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1910.304(c) Outside conductors, 600 volts, nominal, or less

Clearance

1. Power conductors on poles

2. Clearance of open conductors from ground:

10 feet – above sidewalk, grade, platform 12 feet – vehicular traffic 15 feet – truck traffic 18 feet – public streets, alleys, driveways

42 ©2006 TEEX

1910.304(c) Outside conductors, 600 volts, nominal, or less

3. Clearance from building openings No outer jacket: 3 foot clearance, except

above window Not beneath or obstructing openings

where materials may be moved

4. Above roofs: 8 ft above, 3 ft from edge Pedestrians? Platform Exceptions for slope, attachment

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1910.304(d) Location of outdoor lamps

d. Location of outdoor lamps Under energized equipment unless

Equipment can be locked out or Clearance/other safeguards adequate

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1910.304(e) Services

Disconnecting means Main switch disconnects all, indicates

on/off

Services over 600 volts, nominal Accessible only to qualified; warning

signs

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1910.304(f) Overcurrent protection

1. 600 volts, nominal, or lessi. Protect conductors and equipment iv. Overcurrent devices readily accessible

To employees & building management Not exposed to damage or ignitable material

v. Located/shielded to avoid injury/burnsvi. On/off position clearly indicatedvii. Vertical: up = on

2. Special rules for over 600 volts

46 ©2006 TEEX

1910.304(g) Grounding

1. Systems to be groundedi. 3-wire DC: neutral conductor

ii. 2-wire DC, >50V-300V, with exceptions

iii. AC <50V in certain cases

iv. AC 50V-1000V (unless exempt) under 4 conditions

v. Exemptions for AC 50V-1000V

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2. Conductor to be grounded

3. Portable and vehicle-mounted generators: frame as grounding electrode

4. Grounding connections

5. Grounding path: permanent, continuous, effective

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Grounding

One conductor of the circuit intentionally grounded to earth

Protects circuit from lightning or other high voltage contact

Stabilizes the voltage in the system so “expected voltage levels” are not exceeded under normal conditions

49 ©2006 TEEX

Grounding

Metal frames / enclosures of equipment grounded by permanent connection or bond

Equipment grounding conductor provides path for dangerous fault current to return to ground

If damage, corrosion, loosening, etc. impairs continuity, shock and burn hazards will develop

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Grounding Path

Shall have capacity to conduct safely any likely fault current.

Fault currents may be many times normal currents; can melt points of poor conductivity

High temperatures = hazard; can destroy ground-fault path

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6. Supports, enclosures, equipmentvi. Exposed non-current-carrying metal parts

of cord- and plug-connected equipment

7. Nonelectrical equipment

8. Methods of grounding fixed equipment

9. Grounding of systems and circuits 1000 volts and over (high voltage)

52 ©2006 TEEX

Ground fault circuit interrupters (GFCI’s)

GFCI overcurrent device like a fuse or circuit breaker

Designed to sense an imbalance in current flow over the normal path

Opens circuit if current in hot and grounded wires differ by 5mA 1mA

Must be installed correctly and tested

Wiring Methods, Components, and Equipment for General Use

1903.305

54 ©2006 TEEX

1910.305(a) Wiring methods

Not applicable to factory-assembled

1. General requirementsi. Metal parts as grounding conductors:

effectively bonded

ii. Internal insulated grounding conductor for isolated enclosure

iii. No wiring systems in ventilation ducts

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2. Temporary wiring Restricted uses Removed after project completion Requirements for feeders and branch

circuits Grounding receptacles No bare conductors or earth returns Disconnecting switches

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2.Temporary wiring, continued Lamps protected from contact or breakage Flexible cords protected from damage Cables supported

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1910.305(b) Cabinets, boxes, and fittings

1. Conductors entering boxes, cabinets, or fittings

Must be protected from abrasion Openings must be closed, with or without

wires running through

2. Covers and canopies Metal covers must be grounded

>600V: complete, secure, marked enclosure

58 ©2006 TEEX

1910.305(c) Switches

Gravity must not close switches Warning if power may still be available

while switch is closed Faceplates where appropriate Grounding

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Switchboards, panelboards, and enclosures for damp locations

Switchboards and panelboards Switchboards with exposed live parts: in

dry places accessible only to qualified persons

Panelboards: in enclosures with no live parts on front

Switches dead when open Enclosures for wet locations

Airspace, weatherproof

60 ©2006 TEEX

1910.305(f) Conductors for general wiring

Insulated unless otherwise permitted Approved type for use Distinguishable by color or other means

Grounded Ungrounded Equipment grounding

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1910.305(g) Flexible cords and cables

In general much more easily damaged Should not be used if recognized

options can be used instead Must be approved for conditions and

location Allowable purposes listed

62 ©2006 TEEX

1910.305(g) Flexible cords and cables

May not be substituted for fixed wiring May not be run through walls, ceilings, floors,

doors, windows May not be attached to buildings May not be concealed in walls, ceilings, floors May not be spliced, except hard service #14 Strain relief needed on connections

63 ©2006 TEEX

Flexible cords: Acceptable?

Short cord as part of a tool? Yes. Temporary use of extension cord for

tool/appliance? Yes. Obviously not temporary? No. Extended over distance to avoid

installing fixed outlet? No.

64 ©2006 TEEX

1910.305(j) Equipment for general use

1. Lighting fixtures, lampholders, lamps, receptacles

2. Receptacles, cord connectors, and attachment plugs (caps)

3. Appliances4. Motors5. Transformers6. Capacitors7. Storage batteries

Specific Purpose Equipment and Installations

1903.306

66 ©2006 TEEX

1910.306 Specific purpose equipment and installations

a. Electric signs and outline lighting

b. Cranes and hoists

d. Electric welders—disconnecting means

g. Induction and dielectric

Hazardous (Classified) Locations1903.307

68 ©2006 TEEX

1910.307 Hazardous (classified) locations

Classification based on flammable vapors, liquids, gases, combustible dusts or fibers

Each area considered individually Classified by classes and divisions or

zones Documentation available for users,

designers, installers, maintainers of electric equipment

69 ©2006 TEEX

1910.307 Hazardous (classified) locations

Definitions of classes and divisions in 1910.399, Definitions Class I: flammable gases/vapors; explosive

or ignitable mixtures Class II: combustible dust Class III: easily ignitable fibers or flyings;

not likely to be in suspension Division 1 & 2 for each; Zones 0-2 for

Class I

70 ©2006 TEEX

1910.307(c) Electrical installations

Equipment must be one of these: Intrinsically safe Approved for hazardous (classified)

location Approved and marked for class and properties

of material present

Safe for hazardous (classified) location NFPA 70 referenced

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Conduits and equipment

d. Conduits: threaded, wrench-tight or bonding jumper

e. Equipment in Division 2 locations: Division 1 approved equipment = OK General-purpose equipment OK if

demonstrably not a source of ignition

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1910.307(f) Protection techniques

Explosionproof apparatus

Dust ignitionproof Dust-tight Purged and

pressurized Nonincendive circuit

Nonincendive equipment Nonincendive component

Oil immersion Hermetically sealed Other protection

techniques

73 ©2006 TEEX

1910.307(g) Class I, Zone 0, 1, and 2 locations

Zone = alternative to divisions for Class 1

Classified by chemical properties and likelihood of combustible atmosphere

Proper installation of conduit & equipment to avoid sparks in flammable/combustible atmosphere

Protection techniques for certain zones

74 ©2006 TEEX

1910.307(g) Class I, Zone 0, 1, and 2 locations

Special precaution: PE must classify areas and specify equipment

Listing and marking: Listed for Zone 0 = OK for Zone 1-2 Listed for Zone 1 = OK for Zone 2 (For same gas or vapor) Marking requirements & exemption

More information in NFPA 70

75 ©2006 TEEX

1910.307(g) Class I, Zone 0

Special Systems1910.308

77 ©2006 TEEX

1910.308 Special systems

a. Systems over 600 volts, nominalb. Emergency power systemsc. Remote control, signaling, and power-

limited circuitsd. Fire alarm systemse. Communications systemsf. Solar photovoltaic systemsg. Integrated electrical systems

Definitions1910.399

79 ©2006 TEEX

1904.399 Definitions

New version supersedes older version in CFR book

References for Further Information1910 SUBPART S APPENDIX A

81 ©2006 TEEX

1910 Subpart S Appendix A

Nonmandatory references aid in understanding

Not a substitute for compliance with CFR Appendices B and C removed

Safety-Related Work Practices1910.331-1910.335

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1910.331 Scope

Qualified persons (who have training in avoiding the electrical hazards)

Unqualified persons (with little or no such training)

Working on or near: Premises wiring Wiring for connection to supply Other wiring Vehicles excluded

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1910.332 Training

a. Scope: employees with electric shock risk not reduced to safe level by installation requirements

b. Training content: Work practices for job assignments 1910.331-335 and others necessary Qualified vs. unqualified

c. Classroom or on-the-job; risk based

85 ©2006 TEEX

Employees to be Trained

Electricians and welders Any others if:

work they do or supervise comes close enough to exposed parts of

electric circuits 50V for hazard to exist

Selection and Use of Work Practices

1910.333

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1910.333 (a)(1) Deenergized parts

Live parts deenergized before employee works on or near them: Unless infeasible or causes greater hazard <50V not deenergized if no increased

exposure to burns or arcs Examples in CFR

If not deenergized, other work practices must protect employees

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1910.333(b) Working on or near exposed deenergized parts

If not locked out or tagged out, treated as energized

Lockout/tagout rules followed in order 1910.147 provisions may also be OK Written copy of procedures available

89 ©2006 TEEX

1910.333(b) Working on or near exposed deenergized parts

Lockout/tagout steps in section (2):ii. Deenergizing equipment

iii. Application of locks and tags

iv. Verification of deenergized condition

v. Reenergizing equipment after work

90 ©2006 TEEX

1910.333(c) Working on or near exposed energized parts

Only qualified persons may work on energized electric circuit parts

For work near overhead lines: Lines deenergized and grounded, or Other protective measures provided

91 ©2006 TEEX

Working near overhead power lines

Unqualified person near energized lines Person and longest conductive object not

closer than 10 ft, + 4 in/10kV above 50kV For elevated or ground work

Qualified person: Closer approach only with insulation Table S-5: distance varies by voltage

Equipment: same distance as unqualified

92 ©2006 TEEX

Working near overhead power lines

Equipment: same distance as unqualified, with exceptions: In transit, structure lowered: 4 ft +4 in/10kV Insulating barriers, not part of vehicle Aerial lift, insulated, with qualified person Ground employees may not contact

equipment without protection or distance Employees may not stand at grounding

location when line contact possible

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4. Illumination must allow safe work – may not reach blindly in

5. Confined space work requires protective insulation & secured doors

6. Conductive materials: prevent contact with energized parts

7. Portable ladders: nonconductive siderails

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8. Conductive apparel not worn, or insulated

9. Housekeeping near live parts: Requires safeguards No conductive cleaning materials,

including liquid solutions

10. Interlocks may only be defeated temporarily by qualified person

Use of Equipment1910.334

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1910.334(a) Portable electric equipment

Handled in a manner to not cause damage

Cords not used to raise/lower equipment

Cords not stapled or hung in ways that damage insulation

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Visual inspection required before use: Portable cord / plug connected equipment Extension cords For external defects and evidence of internal

damage If not exposed to damage, only when relocated

Defect or damage: remove, do not use until repaired and tested

Plug and receptacle checked for compatibility

98 ©2006 TEEX


Grounding type equipment: ground must be maintained

Conductive work locations (e.g. wet) require approved equipment and cords

Connecting plugs: Never plug or unplug live equipment with

wet hands Protect hands from conductive path (water) Locking connectors: properly secured

99 ©2006 TEEX

1910.334(b) Electric power and lighting circuits

Never reenergize a blown fuse Never reenergize a circuit breaker until

it is safe (Overload or fault?) Never modify overcurrent protection

beyond § 304 requirements

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1910.334(c) and (d)

c. Test instruments and equipment Only qualified persons may test electric

circuits or equipment Test instruments must be visually

inspected Must be rated for circuits & environment

d. Occasional use of flammable and ignitable materials: Do not use equipment that could ignite them

Safeguards for Personnel Protection

1910.335

102 ©2006 TEEX

1910.335(a) Use of protective equipment

Personal protective equipment Must be provided with & use equipment Maintained, inspected, and tested Insulating material protected Nonconductive head protection Eye or face protection for arcs, flashes,

flying objects from explosions Insulated tools or handling equipment Shields, insulation for heating/arcing

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1910.335(b) Alerting techniques

Techniques to warn and protect employees: Safety signs and tags Barricades Attendants

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Relevant Standards Outside 29 CFR 1910

29 CFR 1926 Subpart K: construction API RP 54

Section 9.14 Generators, Motors, and Lighting

Section 10: Drilling and Well Servicing Rig Electrical Systems

API RP 14F for offshore wiring API RP 500 and 505: area classification

105 ©2006 TEEX

Clues that Electrical Hazards Exist

Tripped circuit breakers or blown fuses Warm tools, wires, cords, connections,

or junction boxes GFCI that shuts off a circuit Worn or frayed insulation around wire or

connection













112 ©2006 TEEX

OSHA Resources

Pub 3075 Controlling Electrical Hazards Small Business Handbook section Inspection Procedures

Electrical Safety-Related Work Practices -- Inspection Procedures and Interpretation Guidelines

113 ©2006 TEEX

Interpretations

Training requirements for employees who perform non-electrical work on electrical equipment

Qualifications for resetting circuits or replacing fuses; electrical enclosures must be approved

Use of compressed air above 30 p.s.i. for cleaning purposes; nonmetallic-sheathed cable for temporary wiring

Electrical Standards MODULE 10. 2©2006 TEEX Hazard Brainstorming Where are electrical hazards on oil and gas well sites?

Documents

teex electrical shock

teex effects of current

electrical hazards

ground slide

electrical danger

niosh slide

teex factors

probable death slide