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Outline of 2002 NESC Changes
Page 1
2002 NESC Changes
by Gerald NewtonThis course discusses the 2002 National Electrical Safety Code Changes
Page 2Review: Organization of the NESCGeneral Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 3Changes to General SectionsGeneral Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 4New Rules for Scope General Sections
01 Introduction
010 Purpose
011 Scope
012 General rules
013 Application
014 Waiver
015 Intent
016 Effective Date
017 Units of Measure
Page 5New additions to 011 Scope011 B. The NESC covers utility facilities and functions up to the service point.
NOTE: The National Electrical Code ( NEC ) , NFPA 70-2002 1 covers utilization wiring requirements beyond the service point.
New Definition: service point. The point of connection between the facilities of the serving utility and the premises wiring.
Definition from the NEC (exactly the same) : Service Point. The point of connection between the facilities of the serving utility and the premises wiring.
Page 6Introduction: Scope Service Point Example
Page 7
Introduction: Scope Service Point Example Dividing line for underground services can vary
Page 8Service Point for Underground ServicesSome utilities provide service to the terminals of the underground meter base. Others provide service to the property lines and the customer provides wiring after that. Other utilities require the customer to provide the secondary wiring from a pad mounted transformer to the meter, and the utility takes control after the final hookup.
Page 9
New011C NESC rules cover street and area lights ( supplied by underground or overhead conductors) under the exclusive control of utilities ( including their authorized contractors) or other qualified persons ( such as those associated with an industrial complex) .
NOTE: Luminaires not under such exclusive control are governed by the requirements of the NEC.
Page 10011C Area Lighting covered by the NESCExample of area lighting covered by the NESC
Page 11011C Area Lighting covered by the NECExample of area lighting covered by the NEC
Page 12015 Intent Review A. The word shall indicates provisions that are mandatory.
B. The word should indicates provisions that are normally and generally practical for the specified conditions. However, where the word should is used, , it is recognized that, in certain instances, additional local conditions not specified herein may make these provisions impractical. When this occurs, the difference in conditions shall be appropriately recognized and Rule 012 shall be met.
Page 13015 New Rules for Intent General Sections
01 Introduction
010 Purpose
011 Scope
012 General rules
013 Application
014 Waiver
015 Intent
016 Effective Date
017 Units of Measure
Page 14015 Intent C, D, and E are NEW C. Footnotes to a table have the force and effect required or allowed by the rule that specifies the use of the table.
D. Exceptions to a rule have the same force and effect required or allowed by the rule to which the exception applies.
E. The word RECOMMENDATION indicates provisions considered desirable, but that are not intended to be mandatory.
F. The word NOTE or the word EXAMPLE used in a rule indicates material provided for information or illustrative purposes only. NOTES and EXAMPLES are not mandatory and are not considered to be a part of Code requirements.
Page 15New Definitions General Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 1602 New Definitions de-energized. Disconnected from all sources of electrical supply by open switches, disconnectors, jumpers, taps, or other means.
NOTE: De-energized conductors or equipment could be electrically charged or energized through various means, such as induction from energized circuits, portable generators, lightning, etc.
Page 1702 New Definitions multigrounded/ multiple grounded system. A system of conductors in which a neutral conductor is intentionally grounded solidly at specified intervals. A multigrounded or multiple grounded system may or may not be effectively grounded. See: effectively grounded.
neutral conductor. A system conductor other than a phase conductor that provides a return path for current
to the source. Not all systems have a neutral conductor. An example is an ungrounded delta system containing
only three energized phase conductors.
Page 1802 New Definitions qualified. Having been trained in and having demonstrated adequate knowledge of the installation, construction, or operation of lines and equipment and the hazards involved, including identification of and exposure
to electric supply and communication lines and equipment in or near the workplace. An employee who is undergoing on-the-job training and who, in the course of such training, has demonstrated an ability to perform
duties safely at his or her level of training, and who is under the direct supervision of a qualified person, is
considered to be a qualified person for the performance of those duties.
Page 1902 New Definitions readily climbable supporting structure. A supporting structure having sufficient handholds and footholds that the structure can be climbed easily by an average person without using a ladder, special tools or devices, or extraordinary physical effort. A supporting structure with a space of 2.45 m ( 8 ft) or more between handholds and footholds starting not more than 1.80 m ( 6 ft) above grade is not readily climbable.
NOTE 1: Round poles, diagonal braces on towers, and guy wires are not considered to be readily climbable.
NOTE 2: Diagonal braces on towers are not considered to be handholds or footholds except that, at their point of attachment to a vertical structural member, they may create a foothold.
Page 2002 New Definitionss service point. The point of connection between the facilities of the serving utility and the premises wiring.
shield wire/ conductor ( also referred to as static wire or ground wire) . A grounded conductor installed to shield transmission or distribution phase conductors from direct lightning strikes.
single grounded system/ unigrounded system. A system of conductors in which one conductor is intentionally grounded solidly at a specific location, typically at the source.
ungrounded system. A system of conductors in which no conductor or point is intentionally grounded, either solidly or through a noninterrupting current-limiting device.
Page 2102 Modified Definition vault. A structurally solid enclosure, including all sides, top, and bottom, above or below ground where entry is limited to personnel qualified to install, maintain, operate, or inspect the equipment or cable enclosed. The
enclosure may have openings for ventilation, personnel access, cable entrance, and other openings required for operation of equipment in the vault.
Page 2202 Vault
Page 23
Review: Organization of the NESC General Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 24097G NEW Separation of Grounding Conductors Communication Systems
Where both electric supply systems and communication systems are grounded on a joint use structure,
either a single grounding conductor should be used for both systems or the electric supply and
communication grounding conductors should be bonded together, except where separation is required
by Rule 097A. Where the electric supply utility is maintaining isolation between primary and
secondary neutrals, the communication system ground shall be connected only to the primary
grounding conductor.
Page 25Example of Rule 097G
Page 26
Rule 99C Recommendation and Note added C. Bonding of Electrodes
A bond not smaller than AWG No. 6 copper or equivalent shall be placed between the communication grounding electrode and the supply system neutral grounding electrode where separate electrodes are used in or on the same building or structure being served.
RECOMMENDATION: If water piping is used as a bonding means, care must be taken to assure that the metallic path is continuous between electrodes.
NOTE: See NEC Article 800-40(d) for corresponding NEC requirements.
Page 27Example of 099C
Page 28
Overview of Changes No changes were made in the 2002 Edition regarding use of earth or sea as a continuous conductor in HVDC systems. Subcommittee 1 reviewed a change proposal with regard to using earth or sea as a continuous conductor and did not see an immediate need to revise the NESC for this type of operation for HVDC systems in the United States. Although several systems in Europe and one in the Philippines currently use sea as a conductor, there are concerns that should be addressed before revising the Code.
Page 29Changes to Part 1General Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 30
Part 1 Changes to Electric Supply Stations In Part 1—Electric Supply Stations, the rules were clarified to be applicable to both ac and dc circuits. DC station clearances were added to the appropriate tables. Requirements were revised to allow exceptions from prohibiting storage of equipment within an electrical supply station. The exception allows storage of material essential for maintenance and temporary storage of material related to work in progress in the station or a nearby transmission line. Restrictions are required to maintain safe clearances and working conditions.
Page 31110B2 Rooms and Spaces in Supply Stations All rooms and spaces in which electric supply equipment is installed shall comply with the following
requirements:
1. Construction
They shall be as much as practical noncombustible.
NOTE: This rule is not intended to prevent wood poles from being used to support conductors or equipment
in electric supply stations.
2. Use
They should be as much as practical free from combustible materials, dust, and fumes and shall
not be used for manufacturing or for storage.
Page 32
110B2 Rooms and Spaces in Supply Stations New Exceptions EXCEPTION 1: Equipment or material essential for maintenance of the installed equipment may be stored if guarded or separated from live parts as required by Rule 124.
EXCEPTION 2: Materials related to station, transmission, or distribution construction or maintenance work may be stored in the station if located in an area separated from the station electric supply equipment by a fence meeting the requirements of Rule 110A.
Page 33110B2 Rooms and Spaces in Supply Stations New Exceptions EXCEPTION 3: Stored material related to station, transmission, and distribution construction and maintenance work in progress may be temporarily located in a storage space meeting all of the following requirements:
( 1) Guarded or separated from live parts as required by Rule 124.
( 2) Station exits continue to meet the requirements of Rule 113.
( 3) Station working space continues to meet the requirements of Rule 125.
( 4) Access is limited to qualified personnel.
( 5) The storage location and content is such that the risk of fire does not unreasonably jeopardize station operation.
( For battery areas, see Section 14; for guarding, see Rule 124; for auxiliary equipment in classified locations, see Rule 127. )
Page 34110B2 Rooms and Spaces in Supply StationsOpen storage of Materials related to station, transmission, or distribution construction or maintenance work in a substation is not allowed unless placed in a fenced area
Page 35110B2 Rooms and Spaces in Supply Stations EXCEPTION 1: Equipment or material essential for maintenance of the installed equipment may be stored if guarded or separated from live parts as required by Rule 124.
Page 36New Table 124-1 Part D for
Direct Current Table values start at 250,000 Volts DC unlike Part A of the AC Table that starts at 150 volts.
Page 37New Table 124-1 Part D Direct Current Vertical Clearance Example
Page 38
New Table 124-1 Part D Direct Current Horizontal Clearance Example124C3 Supplemental Barriers or Guards Within Electric Supply Stations
Page 39Deletion from Part 1A Tentative Interim Amendment (TIA) was approved to remove the implication that grounding may be omitted when working on conductors normally operating at 25 kV or less where a visible open switch exists. The statement is not applicable to Part 1, and it may be a leftover practice that is no longer valid.
Page 40Changes to Part 2 General Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 41
Overview of Changes Part 2 In Part 2—Overhead Lines, additional wording was added to address the situation of supply workers working in close proximity to communication antennas. New wording was also added to cover clearance of line conductors from communication antennas, and to clarify clearances of conductors from grain bins, boat launching areas, service drops, support arms, and lighting luminaires. Clarification was added to relationship of approach distances for non-utility workers from overhead lines and associated equipment.
Page 42Overview of Changes Part 2A major revision of Sections 25 and 26 on Strength and Loadings has begun and will span at least 3 Code cycles by the time it is completed. This is due to more sophisticated structural calculations that will be required, e.g., Load and Resistance Factor Design (LRFD), updated and improved input data from new wind and ice maps, and new pole materials that will supplement wood.
Page 43
Overview of Changes Part 2 Some change proposals were incorporated into the 2002 edition; others will be deferred until a later edition when the industry has become more familiar with the nature of these changes. For this edition, proposals were accepted to 1) treat wood, steel, and concrete poles with consistent Overhead Factors, and 2) include a new Extreme Wind Map that uses a new 3-s gust criteria, replacing the existing fastest mile wind. In addition, expanded calculations are required due to the use of gust response factor, importance factor, and velocity pressure coefficient.
Page 44Part 2 Safety Rules for the Installation and Maintenance or Overhead Electric Supply and Communication LinesSection 20 Purpose, Scope, and Application of Rules
200 The Purpose is the practical safeguarding of persons during the installation, operation, or maintenance of overhead supply and communication lines and their associated equipment.
Page 45Part 2 Scope201 Scope
Part 2 of this code covers supply and communication conductors and equipment in overhead lines. It covers the associated structural arrangements of such systems and the extension of such systems into buildings. The rules include requirements for spacing, clearances, and strength of construction. They do not cover installations in electric supply stations except as required by Rule 162A.
Page 46Part 2 Scope: Two new Notes addedNEW NOTE 1:
Part 4 contains the approach distances and work rules required of supply and communication employers and their employees working on or near supply and communication lines and equipment.
NEW NOTE 2:
The approach distances to energized parts, and other requirements applicable to the activities of utility or non-utility construction personnel, and others in close proximity to existing supply lines are governed by the Occupational Health and Safety Administration (OSHA), federal, state, or local statutes or regulations.
Page 47State of Alaska Crane LawAS Sec. 18.60.670. Prohibition against placement of equipment near electrical power lines and conductors.
A person individually or through an agent or employee may not
(1) place any type of tool, equipment, machinery, or material that is capable of lateral, vertical, or swinging motion, within 10 feet of a high voltage overhead electrical line or conductor;
(2) store, operate, erect, maintain, move, or transport tools, machinery, equipment, supplies, materials, apparatus, buildings, or other structures within 10 feet of a high voltage overhead electrical line or conductor.
Page 48Approach Distances Rules vary The NESC, NFPA 70 E, and OSHA have many rules for approach distances for working on energized parts.
NESC rules are in Part 4
NFPA 70E rules are in Part 2
Federal OSHA has rules in CFR 1910.269
In Alaska OSHA is administered by AKOSH that adopts federal rules.
The 10 foot crane rule is an Alaskan Statue.
Page 49New Table 232-2 applies to Luminaires232B4. Street and Area Lighting
a. The vertical clearance of street and area lighting luminaires shall be not less than that shown in Table 232-2. For this purpose, grounded luminaire cases and brackets shall be considered as effectively grounded equipment cases; ungrounded luminaire cases and brackets shall be considered as a rigid live part of the voltage contained.
EXCEPTION:
This rule does not apply to post-top mounted luminaires with grounded or entirely dielectric cases.
Page 50New Table 232-2 applies to Luminaires
Page 51
New Table 232-2 as it applies to Luminaires Example
Page 52
234F1 New Clearance Rules for Grain Bins234F1 covers Grain Bins Loaded by Permanently Installed Augers, Conveyers, or Elevator Systems
Two new rules:
a. A clearance of not less than 5.5 m (18 ft) in all directions above the grain bin shall be maintained from each probe port in the grain bin roof for all wires, conductors, and cables.
b. A horizontal clearance of not less than 4.6 m (15 ft) shall be maintained between grain bins and open supply conductors, 0 to 22 kV.
Page 53
234F1 New Clearance Rules for Grain Bins Example
Page 54
235H NewH. Clearance and Spacing Between Communication Conductors, Cables, and Equipment
1. The spacing between messengers supporting communication cables should be not less than 300 mm (12 in) except by agreement between the parties involved.
2. The clearances between the conductors, cables, and equipment of one communication utility to those of another, anywhere in the span, shall be not less than 100 mm (4 in), except by agreement between the parties involved.
Page 55235H New Example
Page 56
235I 1 New235 I Clearances in Any Direction From Supply Line Conductors to Communication Antennas in the Supply Space Attached to the Same Supporting Structure
1. General
Communication antennas located in the supply space shall be installed and maintained only by personnel authorized and qualified to work in the supply space in accordance with the applicable rules of Sections 42 and 44. See also Rule 224A.
Page 57235I 2 New2. Communication Antenna
The clearance between a communication antenna operated at a radio frequency of 0 to 750 V and a supply line conductor shall be not less than the value given in Table 235-6, row 1b.
NOTE: The antenna functions as a rigid, vertical or lateral open wire communication conductor.
Page 58New Note added to Table 235-613 These clearances apply to communication antennas operated at a radio frequency at 0 to 750 V. Also see Rules 235I4 and Rule 239.
Page 59New Note added to Table 235-6 Example using Table 235-6 for communication lines on jointly used structures row 1b and Note 13 the minimum clearance from the antenna to the communications cable is 3 inches
Page 60New 235I 2 reference to Table 235-6 1b Example using 12.47/7.2 Kv, 3-ph, 4-w line on jointly used structures row 1b
The Clearance required is 6” + 0.4(12.47-8.7)=7.51 inches
Page 61235I 3 New3. Equipment Case That Supports a Communication Antenna
The clearance between an equipment case that supports a communication antenna and a supply line conductor shall be not less than the value given in Table 235-6, Row 4a.
Page 62New 235I 3 reference to Table 235-6 4a Example using 12.47/7.2 Kv, 3-ph, 4-w line on jointly used structures row 1b
The Clearance required is 5” + 0.2(12.47-8.7)=5.75 inches
Page 63235I 4 New4. Vertical or Lateral Communication Conductors and Cables Attached to a Communication Antenna
The clearance between a supply line conductor and the vertical or lateral communication conductor and cable attached to a communication antenna shall be not less than the value given in Rule 239.
Page 64New 235I 4 reference to
Rule 239 and Table 239-1 Example using 12.47/7.2 Kv, 3-ph, 4-w line on jointly used structures row 2b
The Clearance required is 6” + 0.4(12.47-8.7)=7.51 inches
Page 65236D2 New Climbing Space Requirement D. Location of Equipment Relative to Climbing Space
1. All supply and communication equipment such as transformers, regulators, capacitors, cable terminals (potheads), amplifiers, loading coils, surge arresters, switches, etc., when located below conductors or other attachments, shall be mounted outside of the climbing space.
2. All exposed ungrounded conductive parts of luminaires and their supports that are not insulated from current-carrying parts shall be maintained at not less than 500 mm (20 in) from the surface of their supporting structure.
EXCEPTION 1:
This may be reduced to 125 mm (5 in) if located on the side of the structure opposite the designated climbing space.
EXCEPTION 2:
This does not apply where the equipment is located at the top or other vertical portion of the structure that is not subject to climbing.
Page 66236D2 Example
Page 67
238E NEW Climbing Space for Communication workers E. Communication Worker Safety Zone
The clearance specifications of Rules 235C and 238 create a communication worker safety zone between the facilities located in the supply space and facilities located in the communication space, both at the structure and in the span between structures. Except as allowed by Rules 238C, 238D, and 239, no supply or communication facility shall be located in the communication worker safety zone.
Page 68Section 25 Loadings for Grades B and C Line design calculations can be found in transmission and distribution line design manuals. Many large utilities develop their own manuals while smaller utilities typically use design manuals published by the Rural Utilities Service (formally the REA).
The USDA REA Design Manual for High Voltage Transmission Lines is available in PDF format by clicking here (15.6 Mbytes)
Additional Design manuals can be found at the USDA site by clicking here
A Cable Sag Calculator is online at this site.
Page 69250A4 NEWThe structural capacity provided by meeting the loading and strength requirements of Sections 25 and 26 provides sufficient capability to resist earthquake ground motions.
Page 70250C Extreme Wind Loading Revised Normally, Light, Medium, and Heavy loading are the three types of loading calculations for wind and ice. Extreme loading has been revised.
Several New Tables and maps added for performing the Extreme Load Design calculations.
New Table 250-2 Velocity Pressure Exposure Coefficient kz, Structure and Wire
New Table 250-3 Structure and Wire Gust Response Factors, GRF
New Table 250-3 Structure and Wire Gust Response Factors, GRF
Revised Maps 250-2(a) and (b)
Page 71251A3. Conductor Loading
Mathematical Model Required An appropriate mathematical model shall be used to determine the wind and weight loads on ice coated conductors and cables. In the absence of a model developed in accordance with Rule 251A4, the following mathematical model shall be used:
a. On a conductor, lashed cable, or multiple-conductor cable, the coating of ice shall be considered to be a hollow cylinder touching the outer strands of the conductor or the outer circumference of the lashed cable or multiple-conductor cable.
b. On bundled conductors, the coating of ice shall be considered as individual hollow cylinders around each subconductor.
Page 72Review of LoadingHeavy Loading – Alaska NESC Figure 250-1
Page 73250-2(a) New Basic Wind Speed Map for Alaska
74 Changes to Part 3General Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 75Overview of Changes Part 3 In Part 3—Underground Lines, the requirements for random separation changed to prohibit both communication lines and power from being any closer than 12 in from fuel or steam lines.
Other new rules address location of pad-mounted equipment and pedestals and cable protection by means of climbing devices required to be installed within the manhole. Also included are revised rules on burial depth for streetlight cables and security of above ground equipment.
Page 76Revise 314BB. Conductive Parts to Be Grounded
Cable sheaths and shields (except conductor shields), equipment frames and cases (including padmounted devices), and conductive lighting poles shall be effectively grounded. Conductive-material ducts and riser guards that enclose electric supply lines or are exposed to contact with open supply conductors of greater than 300 V shall be effectively grounded.
EXCEPTION: This rule does not apply to parts that are 2.45 m (8 ft) or more above readily accessible surfaces or are otherwise isolated or guarded.
Page 77323C5 New Rule for Manhole Access Any manhole greater than 1.25 m (4 ft) in depth shall be designed so it can be entered by means of a ladder or other suitable climbing device. Equipment, cable, and hangers are not suitable climbing devices.
Page 78323E3 NEW Where accessible to the public, access doors to utility tunnels and vaults shall be locked unless qualified persons are in attendance to restrict entry by unqualified persons. When vaults and utility tunnels contain exposed live parts, a prominent safety sign shall be visibly posted before entering the vault.
NOTE: ANSI Z535.1-1998, ANSI Z535.2-1998, ANSI Z535.3-1998, ANSI Z535.4-1998, and ANSI Z535.5-1998 contain information regarding safety signs.
Page 79341A 6 and 7 Revised 6. Supply cables shall not be installed in the same duct with communication cables unless all of the cables are operated and maintained by the same utility.
7. Communication cables may be installed together in the same duct provided all utilities involved are in agreement.
Page 80354E New Supply and Communication Cables or Conductors and Non-Metallic Water and Sewer Lines
1. Supply cables and conductors and non-metallic water and sewer lines may be buried together with no deliberate separation between facilities and at the same depth, provided all parties involved are in agreement.
2. Communication cables and conductors and non-metallic water and sewer lines may be buried together with no deliberate separation between facilities and at the same depth, provided all parties involved are in agreement.
3. Supply cables or conductors, communication cables or conductors, non-metallic water and sewer lines may be buried together with no deliberate separation between facilities and at the same depth, provided the applicable rules in Rule 354D are met and all parties involved are in agreement.
Page 81New 12 inch separation requirement 353. Deliberate Separations—Equal to or Greater than 300 mm (12 in) From Underground Structures or Other
A. General
1. These rules apply to a radial separation of supply and communication cables or conductors from each other and from other underground structures such as sewers, water lines, gas and other fuel lines, building foundations, steam lines, etc., when separation is equal to or greater than 300 mm (12 in).
NOTE: For radial separation less than 300 mm (12 in) see Rule 354.
2. The radial separation should be adequate to permit access to and maintenance of either facility to limit damage to the other.
Page 82353 New 12 inch separation requirement Example
Page 83
353 New 12 inch separation requirement Example
Page 84
353New 12 inch separation for Random Separation354. Random Separation—Separation Less Than 300 mm (12 in) from Underground
Structures or Other Cables
Page 85
A. General
1. These rules apply to a radial separation of supply and communication cables or conductors from each other and from other underground structures when the radial separation between them will be less than 300 mm (12 in).
2. Radial separation of supply and communications cables or conductors from steam lines, gas, and other fuel lines shall be not less than 300 mm (12 in) and shall meet Rule 353.
Page 86354 Random Separation General Requirement Supply, communications, and supply and communications can be buried in the same trench with no separation if all parties agree and if a set of rules in 354 are met.
Page 87354 Rules for Random Separation
Page 88
354 Rules for Random Separation If the rules in 354 cannot be met then an alternative plan must be used.
There are two basic alternatives:
Use a conduit system
Use 12 inches of separation
Page 89380D NewD. Pad-mounted equipment, pedestals, and other above ground enclosures, should be located not less than 1.2 m (4 ft) from fire hydrants.
EXCEPTION: Where conditions do not permit a clearance of 1.2 m (4 ft), a clearance of not less than 900 mm (3 ft) is allowed.
Page 90380D Example
Page 91
Changes to Part 4 General Sections
01 Introduction
02 Definitions
03 References
09 Grounding Methods
Page 92Revised 410A2 Employer to Provide Training The employer shall provide training to all employees who work in the vicinity of exposed energized facilities. The training shall include applicable work rules required by this Part and other mandatory referenced standards or rules. The employer shall ensure that each employee has demonstrated proficiency in required tasks. The employer shall provide retraining for any employee who, as a result of routine observance of work practices, is not following work rules.
Page 93411D Revised Rule requiring conspicuous safety signs at all entrances to electric supply stations, substations, and other enclosed walk-in areas containing exposed current-carrying parts has been removed.
D. Signs and Tags for Employee Safety. Safety signs and tags required by Part 4 shall comply with the provisions of ANSI Z535.1-1998 through ANSI Z535.5-1998, inclusive.
Page 94New 423C4 When a torch or open flame is used (as in heat shrink splicing) in proximity to a visibly exposed gas or other fuel line(s), adequate air space or a barrier shall be provided to protect the gas or fuel line(s) from the heat source.
Page 95424D5 New When a worker is required to perform tasks in trenches or excavations where a cave-in hazard exists or the trench or excavation is in excess of 1.5 m (5 ft) in depth, shoring, sloping, or shielding methods shall be used to provide employee protection.
Page 96424D5 Example Shoring, sloping, or shielding methods must be used to provide employee protection.
Page 97424D5 Example Shoring, sloping, or shielding methods must be used to provide employee protection.
Page 98431 Revised and Expanded Altitude correction factor added431. Approach to Energized Conductors or Parts
A. No employee shall approach, or bring any conductive object, within the distances to any exposed energized part as listed in Table 431-1. When repairing storm damage to communication lines that are joint use with electric supply lines at that or another point, employees shall:
1. Treat all such supply and communication lines as energized to the highest voltage to which they are exposed, or
2. Assure that the supply lines involved are de-energized and grounded in accordance with Section 441.
B. Altitude Correction
The distances in Tables 431-1 shall be used at elevations below 900 m (3000 ft). Altitude correction factors as indicated in Table 441-5 shall be applied above that altitude. Altitude correction factors shall be applied only to the electrical component of the minimum approach distance.
Page 99441A1a Revised Line or part must be De-energized and Grounded441. Energized Conductors or Parts
Employees shall not approach, or knowingly permit others to approach, any exposed ungrounded part normally energized except as permitted by this rule.
A. Minimum Approach Distance to Live Parts
1. General Employees shall not approach or bring any conductive object within the distances to exposed parts that operate at the voltages listed in Table 441-1 or Table 441-4 unless one of the following is met:
a. The line or part is de-energized and grounded per Rule 444D.
(1997 Code only required de-energizing.)
Page 100441E1 Revised - Grounded added.E. Tagging Electric Supply Circuits Associated With Work Activities
1. Equipment or circuits that are to be treated as de-energized and grounded per Rule 444D shall have suitable tags attached to all points where such equipment or circuits can be energized.
Page 101443G Grounded addedG. Switchgear
Switchgear shall be de-energized and grounded per Rule 444D prior to performing work involving removal of protective barriers unless other suitable means are provided for employee protection. The personnel safety features in switchgear shall be replaced after work is completed.Page 102
De-Energize and Ground Also Required by other Standards
NFPA 70E 2000 2-1.1.3(f) Standard for Electrical Safety Requirements for Employee Workplaces
OSHA 1910.268(m)(1) Telecommucnications (Operation and Maintenance)
OSHA 1910.269 Electric Power Generation, Transmission, and Distribution (Operation and Maintenance)
OSHA 1926.960 Power Transmission and Distribution (Construction)
Page 103
441A3 New Table for Insulated Glovesb. When the Rubber Glove Work Method is employed, rubber insulating gloves, insulated for the maximum use voltage as listed in Table 441-6, shall be worn whenever employees are in the vicinity of energized conductors or parts, supplemented by one of the following two protective methods:
Page 104441A3 New Table for Insulated Gloves (1) The employee shall wear rubber insulating sleeves, insulated for the maximum use voltage as listed in Table 441-6, in addition to the rubber insulating gloves.
EXCEPTION : When work is performed on electric supply equipment energized at 750 V or less, rubber sleeves are not required if only the live parts being worked on are exposed.
Page 105New Table 441-6
Page 106
Rule 447 moved from 276 in 1997 Code 447. Protection Against Arcing and Other Damage While Installing and Maintaining Insulators and Conductors
In installing and maintaining insulators and conductors, precautions shall be taken to limit the opportunity for, as far as is practical, any damage that might render the conductors or insulators liable to fall. Precautions shall also be taken to prevent, as far as is practical, any arc from forming and to prevent any arc that might be formed from injuring or burning any parts of the supporting structures, insulators, or conductors.
Page 107Excellent NESC LinksAn excellent Paper on Proposed Changes in the 2002 NESC by George Bagnall, Director, Electric Staff Division, RUS is available in PDF format Online by clicking here.
Note: Most of the proposed changes in this paper were adopted.
PAPERS FROM RUS 2000 ELECTRIC ENGINEERING SEMINAR
RUS Electric Program Bulletins and Informational Publications contains links to many design manuals!
IEEE National Electrical Safety Code Zone contains 2002 NESC errata sheets and NESC Interpretations for the past 10 years.Back to Login Page