Electrical Safety Regulations Quiz

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Questions and Answers

When are safety signs required for readily climbable supporting structures carrying open supply conductors?

  • Only if they are adjacent to roads, regularly traveled pedestrian thoroughfares, or places where persons frequently gather. (correct)
  • Only if they are not isolated and access to the supporting structure is not limited by a fence.
  • Whenever they are adjacent to regularly traveled pedestrian thoroughfares.
  • Only if they are adjacent to schools or public playgrounds.

What is the minimum distance from the ground or other accessible surface that permanently installed steps on supporting structures should be?

  • 3.05 meters (10 feet)
  • 1.22 meters (4 feet)
  • 1.83 meters (6 feet)
  • 2.45 meters (8 feet) (correct)

When are barriers required for supporting structures with temporarily installed steps less than 2.45 meters (8 feet) from the ground?

  • Always, regardless of location.
  • Only if the structure is not isolated.
  • Only if the structure is not isolated and access is not limited by a fence. (correct)
  • Only if the structure is attended.

What is the minimum distance required between the lowest standoff bracket and the ground or other accessible surface on supporting structures?

<p>2.45 meters (8 feet) (A)</p> Signup and view all the answers

Which of the following is NOT an exception to the rule requiring barriers or signs on readily climbable supporting structures?

<p>The structure is regularly inspected by authorized personnel. (D)</p> Signup and view all the answers

What is the purpose of identifying supporting structures carrying supply or communication conductors?

<p>To facilitate identification by employees authorized to work on the structures. (C)</p> Signup and view all the answers

Where can you find information regarding safety signs to be used in place of a safety word message?

<p>ANSI Z535.3-2011 (D)</p> Signup and view all the answers

What is the minimum height requirement for a fence to limit access to a supporting structure and exempt it from barrier requirements?

<p>The fence must meet the height requirements of Rule 110A1. (D)</p> Signup and view all the answers

What is the requirement for attachments to utility structures?

<p>Attachments require the concurrence of the structure owner and, if applicable, the occupant(s) of the space where the attachment is made. (A)</p> Signup and view all the answers

What are the requirements for climbing spaces around utility lines?

<p>Climbing spaces must be free of any obstructions and climbing hazards. (B)</p> Signup and view all the answers

What is the requirement for supporting overhead conductors?

<p>Conductors should be supported on structures that are solely or principally designed for their support. (C)</p> Signup and view all the answers

What is the requirement for the ground end of anchor guys exposed to pedestrian traffic?

<p>It must be marked with a conspicuous marker. (C)</p> Signup and view all the answers

What is the requirement for anchor guys located in established parking areas?

<p>They can be protected from vehicle contact or marked. (C)</p> Signup and view all the answers

Why does the rule state that it is not practical to protect guys from contact by out of control vehicles operating outside of established traveled ways?

<p>Because it is not practical to protect guys from contact by out of control vehicles operating outside of established traveled ways. (B)</p> Signup and view all the answers

What does the NESC stand for?

<p>National Electrical Safety Code (A)</p> Signup and view all the answers

Why is vegetation management important around power lines?

<p>To ensure the safety and reliability of the power lines. (B)</p> Signup and view all the answers

When supply conductors are carried below communication conductors, where should transformers and associated apparatus be attached?

<p>To the sides of the support arm, below the supply wires (A)</p> Signup and view all the answers

What is the recommended placement of lateral runs of supply circuits carried below the communication space?

<p>They should be placed on the underside of the support arm, protected by wood molding or insulation. (B)</p> Signup and view all the answers

When supply conductors of different voltage classifications cross each other, which rule generally applies to their placement?

<p>The higher voltage conductors should always be placed above the lower voltage conductors. (B)</p> Signup and view all the answers

If supply conductors of different voltage classifications are on the same structure owned by the same utility, which should be placed higher?

<p>The higher voltage conductors should be placed above the lower voltage conductors. (A)</p> Signup and view all the answers

When supply conductors of different voltage classifications are on the same structure owned by different utilities, how should they be arranged?

<p>Each utility's conductors should be grouped together, with the higher voltage conductors within each group placed above the lower voltage conductors. (C)</p> Signup and view all the answers

What does the text suggest regarding the identification of overhead conductors and cables?

<p>They should be located, marked, numbered, or attached to distinctive insulators or crossarms to facilitate identification. (B)</p> Signup and view all the answers

What is the purpose of systematic transposition of conductors?

<p>It is not prohibited by this text, but this text does not discuss transposition. (A)</p> Signup and view all the answers

What is the primary focus of the text regarding overhead conductors and cables?

<p>Providing guidelines for safe and efficient placement and identification of conductors and cables. (D)</p> Signup and view all the answers

What type of cable requires a continuous auxiliary semi-conducting shield and suitable metallic drainage?

<p>Cables of any voltage, not included in Rule 230C1, covered with a continuous auxiliary semi-conducting shield in combination with suitable metallic drainage and supported on and cabled together with an effectively grounded bare messenger. (B)</p> Signup and view all the answers

What is the clearance requirement for neutral conductors associated with circuits of 0 to 22 kV to ground?

<p>The same clearances as guys and messengers (C)</p> Signup and view all the answers

Which of the following is NOT a requirement for cables that can be cabled together with an effectively grounded bare messenger or neutral?

<p>Covered conductors with sufficient dielectric strength to limit the likelihood of a short circuit (D)</p> Signup and view all the answers

What is the maximum voltage that insulated, nonshielded cable, supported on and cabled together with an effectively grounded bare messenger or neutral, can operate at?

<p>5 kV phase to phase (A)</p> Signup and view all the answers

What is the key factor that allows for reduced clearances between covered conductors?

<p>The ownership and maintenance of the conductors (E)</p> Signup and view all the answers

What is the main purpose of a continuous auxiliary semi-conducting shield in combination with suitable metallic drainage?

<p>To improve the insulation resistance and prevent arcing faults (C)</p> Signup and view all the answers

Which of the following types of cables can be considered as bare conductors for clearance requirements?

<p>Cables with covered conductors (A)</p> Signup and view all the answers

What is the most important factor to consider when determining the clearance requirements for neutral conductors in supply circuits?

<p>The voltage rating of the circuit (A)</p> Signup and view all the answers

What is the required minimum distance for insulators in metallic suspension ropes for lighting units?

<p>2.45 m (8 ft) (A)</p> Signup and view all the answers

For voltages between 22 and 470 kV, how should the clearance be adjusted according to Rule 232B1 and Rule 232B2?

<p>Increase at 10 mm (0.4 in) per kilovolt (B)</p> Signup and view all the answers

What additional clearance rate is specified for voltages exceeding 50 kV at heights greater than 1000 m?

<p>3% for each 300 m (A)</p> Signup and view all the answers

What should clearances be based on for lines operating over 50 kV?

<p>The maximum operating voltage (B)</p> Signup and view all the answers

For voltages exceeding 98 kV ac to ground, what is allowed regarding clearances?

<p>Increasing clearances or using other means (D)</p> Signup and view all the answers

How is the clearance determined for voltages exceeding 470 kV?

<p>By applying the method given in Rule 232D (D)</p> Signup and view all the answers

What is the acceptable steady-state current limit due to electrostatic effects for certain clearances?

<p>5 mA rms (B)</p> Signup and view all the answers

What is the required sag state of conductors for determining clearances at high temperatures?

<p>At 50 °C (120 °F) (C)</p> Signup and view all the answers

What is the minimum horizontal clearance required from the nearest track rail if supporting structures are less than 6.7 m above the rail?

<p>3.6 m (12 ft) (A)</p> Signup and view all the answers

Under what conditions may supports for overhead trolley-contact conductors be located near their own track rail?

<p>If permanent screens are in place for passenger protection (A)</p> Signup and view all the answers

Which of the following represents an exception regarding vertical clearances for overhead wires?

<p>Clearance requirements may be reduced by agreement with railroad(s). (D)</p> Signup and view all the answers

Which temperature condition is NOT specified for determining vertical clearances under Rule 232B1?

<p>Conductor temperature at 35 °C (95 °F) under wind conditions (D)</p> Signup and view all the answers

What is the exception regarding clearances for loading and unloading at industrial sidings?

<p>Clearance of at least 2.13 m (7 ft) is permitted if space is sufficient. (A)</p> Signup and view all the answers

What minimum horizontal clearance must be maintained above the nearest track rail for structures with equipment attached?

<p>3.6 m (12 ft) (A)</p> Signup and view all the answers

What is one of the objectives for providing sufficient clearance along tracks?

<p>To avoid obstruction of signals and signs (B)</p> Signup and view all the answers

What proves to be a necessary condition for supporting structures located near tracks?

<p>They shall ensure an uninterrupted view of adjacent signals. (A)</p> Signup and view all the answers

Flashcards

Climbable structures

Structures like poles or towers designed to support conductors and prone to unauthorized climbing.

Safety barriers

Barriers that prevent unauthorized access to climbable structures.

Height requirement for steps

Steps on supporting structures must be at least 2.45 m (8 ft) high from the ground.

Temporary steps rule

Temporary steps under 2.45 m must have supervision or barriers to prevent climbing.

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Standoff brackets

Brackets on structures that must be 2.45 m apart or from the ground for safety.

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Identification of structures

Structures must be easily identified for authorized employees to work on.

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Exceptions to rules

Certain rules do not apply where structures are isolated or fenced.

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Safety signs and symbols

ANSI standards detail safety signs and symbols for communication safety.

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Utility line attachments

Attachments to utility lines require owner and occupant consent.

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Climbing space clearance

Attachments must not obstruct the climbing space for utility personnel.

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Obstructions and hazards

Attachments must not create climbing hazards or obstructions.

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Supporting conductors

Conductors should not be supported on non-designated structures.

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Guy markers

Anchor guys in pedestrian areas require clear markers for safety.

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Vegetation management

Vegetation should be managed around supply and communication lines.

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Marking anchor guys

Angled support guys in parking areas should be marked or protected.

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NESC compliance

All attachments must comply with the National Electrical Safety Code (NESC).

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Support Arm Conductors

Supply conductors below communication conductors must attach only to support arms.

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Lateral Runs Protection

Lateral supply circuits below communication space need protection with wood molding or insulated cable.

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Voltage Classifications

Supply lines are classified by voltage: 0-750 V, >750 V-8.7 kV, >8.7 kV-22 kV, >22 kV-50 kV, >50 kV.

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Conductors Crossing

Higher voltage conductors should be placed higher when they cross lower voltage conductors.

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Utility Ownership

Conductors of higher voltage should be above lower voltage on structures owned by one utility.

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Mixed Utility Circuits

Circuits of different utilities may group, but higher voltages should remain above lower voltages.

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Identification of Conductors

Conductors must occupy uniform positions and be marked for easy identification.

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Transposition of Conductors

Systematic transposition of conductors is allowed for identification purposes.

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Grounded Messenger

A bare messenger or neutral conductor that supports cables and is effectively grounded.

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Metal Sheath

A continuous metal covering around cables, providing grounding protection.

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Multi-grounded System

A system designed to operate at 22 kV or lower with additional grounding features.

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Covered Conductors

Conductors that are insulated but considered bare for clearance regulations.

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Conductor Clearance

The required space between conductors to prevent contact and ensure safety.

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Neutral Conductors

Conductors that carry current back to the source and must be grounded effectively.

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Phase Conductors

Conductors in a circuit that carry current to the load.

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Fiber-optic Cable

Cables that use light to transmit data, often used in telecommunications.

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Clearances above tracks

Supporting structures must maintain clearances of at least 6.7 m above tracks.

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Minimum clearance rule

Minimum horizontal clearance must be 3.6 m (12 ft) from the nearest track rail.

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Exceptions to minimum clearance

Clearance can be reduced to 2.13 m (7 ft) under certain conditions.

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Trolley-contact conductors

Supports for overhead trolley-contact conductors may have different location rules.

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Signal visibility requirements

Structures must be positioned to ensure clear visibility of signals and signs.

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Industrial sidings clearance

At industrial sidings, minimum clearance can be 2.13 m (7 ft) if enough room for loading is provided.

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Conductor temperature rules

Vertical clearances depend on conductor temperature and loading that affects sag.

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Maximum conductor temperature

Clearance rules apply to the maximum operating temperature higher than 50 °C (120 °F).

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Exception for Luminaires

The rule excludes post-top mounted luminaires with grounded or dielectric cases.

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Insulator Placement

Insulators must be at least 2.45 m (8 ft) from the ground in metallic supports.

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Clearances for High Voltage

Clearances greater than Rule 232B are required for specific high voltages.

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Voltage Exceeding 22 kV

For 22-470 kV, increase clearance by 10 mm per kV over 22 kV.

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Determining Clearances

Clearances for voltages above 470 kV are determined by specific methods in Rule 232D.

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Clearance Adjustments Over 50 kV

For voltages >50 kV, increase clearance by 3% for every 300 m above sea level after 1000 m.

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Limiting Electric Field Effects

For over 98 kV, clearances must increase or effects must be managed to limit current to 5 mA rms.

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Final Sag Consideration

Conductors must be at a final sag at 50 °C (120 °F) during clearance assessments.

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Study Notes

Safety Rules for Overhead Electric Supply and Communication Lines

  • Purpose: The code ensures the safety of people during the installation, operation, and maintenance of overhead supply and communication lines and their associated equipment.
  • Scope: Covers overhead supply and communication conductors and associated structural arrangements, including extensions into buildings. Excludes installations in electric supply stations except as per Rule 162A.
  • Application of Rules: General requirements for application are detailed in Rule 13. When replacing a supporting structure, the equipment arrangement must adhere to the current version of Rule 238C.
  • Referenced Sections: Applies the Introduction (Section 1), Definitions (Section 2), References (Section 3), and Grounding methods (Section 9).
  • Induced Voltages: Cooperative actions are recommended in managing induced voltages from adjacent systems. No specific rules are detailed; however, notice and appropriate procedures are recommended.

General Requirements

  • Referenced Sections: The Introduction, Definitions, References, and Grounding methods apply.
  • Accessibility: All operational parts must be accessible for inspection/maintenance. This includes sufficient climbing and working space.

Inspection and Tests of Lines and Equipment

  • Initial Compliance: Lines and equipment should meet safety rules from the start.
  • Inspection Frequency: Inspections should be performed at intervals determined by past experiences. Inspections may be done as part of other related duties, as needed.
  • Tests: Necessary tests will be conducted to determine the maintenance requirements.
  • Record Keeping: Records of any conditions or defects identified during inspections or tests should be maintained until addressed. Defects that could endanger lives or property require prompt action.

Grounding of Circuits, Supporting Structures, and Equipment

  • Grounding Methods: Adherence to methods outlined in Section 9 is necessary.
  • Common Neutral: Conductors used as common neutrals for primary/secondary circuits require effective grounding. Certain exceptions exist for specific circuit designs.
  • Other Neutrals: Primary, secondary, and service neutral conductors must be effectively grounded, with defined exceptions for ground-fault detecting and current-limiting devices, and those circuits with single-point grounded neutrals.
  • Surge Arresters: Grounding must be effective when surge arresters are in operation.
  • Earth Use in Circuits: Supplying circuits should not primarily use the earth as a conductor. Monopolar operation of bipolar HVDC systems is permitted during emergencies and limited periods of maintenance.
  • Non-Current-Carrying Parts: Metal/reinforced structures, conduits, sheaths, switch handles, and operating rods require effective grounding. Wood structures with metal reinforcement are excluded.

Arrangement of Switches

  • Accessibility: Switches and their control mechanisms must be readily accessible to authorized personnel.
  • Position Indication: Switch positions should be clearly visible or indicated.
  • Locking: Mechanisms must be locked or secured, except during operation or testing.
  • Consistent Positioning: The handles and controls throughout a system should have consistent placement, for safety.

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Related Documents

Safety Rules for Overhead Lines (2017) - NEC PDF

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