NCCER Electrical L2 M7 MIX

1.0x

NCCER Electrical L2 M7 MIX

Created 3 years ago

Duration 0:00:00
lesson view count 586
Select the file type you wish to download
Slide Content
  1. Objectives

    Slide 2 - Objectives

    • When trainees have completed this lesson, they should be able to do the following:
    • 1. Describe the components that make up a cable tray assembly.
    • 2. Explain the methods used to hang and secure cable tray.
    • 3. Describe how cable enters and exits cable tray.
    • 4. Select the proper cable tray fitting for the situation.
    • 5. Explain the National Electrical Code® (NEC®) requirements for cable tray installations.
    • 6. Select the required fittings to ensure equipment grounding continuity in cable tray systems.
    • 7. Interpret electrical working drawings showing cable tray fittings.
    • 8. Size cable tray for the number and type of conductors contained in the system.
    • Cable Tray 26207-14
  2. Performance Tasks

    Slide 3 - Performance Tasks

    • 1. Generate a list of materials for a cable tray layout. List all the components required, including the fasteners required to complete the system.
    • 2. Join two straight, ladder-type cable tray sections together.
    • Cable Tray 26207-14
  3. 1.0.0

    Slide 4 - 1.0.0

    • Cable Tray 26207-14
    • Introduction
    • • Cable trays are used to support wiring systems in industrial applications.
    • • NEC Article 392 covers the requirements for cable tray.
  4. 1.0.0

    Slide 5 - 1.0.0

    • Cable Tray 26207-14
    • Cross Section of Cable Tray Comparing Usable Dimensions to Overall Dimensions
    • • Cable tray dimensions vary according to the tray design.
    • • Cable tray has specific fill requirements in the same way as boxes and conduit.
  5. 1.0.0

    Slide 6 - 1.0.0

    • Cable Tray 26207-14
    • Cables Rest on the Bottom of the Tray and are Held in Place by the Longitudinal Side Rails
  6. 1.0.0

    Slide 7 - 1.0.0

    • Cable Tray 26207-14
    • Two Applications of Cable Tray Channel
    • • Channels are used to carry cable from the tray to the point of use or termination.
    • • NEC® and National Electrical Manufacturers Association (NEMA) standards must be followed when designing and installing cable tray systems.
  7. 2.0.0 – 2.13.1

    Slide 8 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Cable Tray Loading
    • • The load capacity of cable tray depends on many factors including the shape and thickness of the side rails and bottom members, rung spacing, support method, and type of material. Refer to the cable tray manufacturer’s capacity information.
    • • Cables must be packed loosely in tray to avoid overloading and loss of efficiency.
  8. 2.0.0 – 2.13.1

    Slide 9 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Determining the Load on Supports
    • • Each support must be able to withstand 1.25 times the full weight of the cable and the tray.
    • • Excess loading will result in deflection of the side rails and tray bottom, and potential failure of the cable tray system.
  9. 2.0.0 – 2.13.1

    Slide 10 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Bending of Loaded Tray
    • • The two types of cable tray failure are longitudinal (side rail) and transverse (rung) failures.
    • • Longitudinal failures occur as bending failures and buckling failures. Bending is more likely with shorter spans, while buckling typically occurs only on longer spans.
  10. 2.0.0 – 2.13.1

    Slide 11 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Load of Cable Creates Bending Moments Along the Span
    • • The stress in the side rails is directly proportional to the bending moments at all points along the tray.
    • • Splices are points of weakness in a cable tray system and should be located within ¼ of the span’s distance from the nearest support whenever possible.
  11. 2.0.0 – 2.13.1

    Slide 12 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Cable Pulley Used to Facilitate a Cable Pull in a Tray
    • • Cable pulleys can be used to facilitate pulling conductors in the tray.
    • • Cable tray covers are used to protect objects from falling into the tray and to protect conductors from sunlight.
  12. 2.0.0 – 2.13.1

    Slide 13 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Several Ways in Which Cables may Exit from a Cable Tray
  13. 2.0.0 – 2.13.1

    Slide 14 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • A Dropout Plate Provides a Curved Surface for the Cable to Follow as it Leaves the Tray
    • • A dropout plate protects conductors from sharp edges and provides a smooth surface for exiting the cable tray.
    • • Dropout plates also reduce stress on the conductor by increasing the bend radius at the dropout point.
  14. 2.0.0 – 2.13.1

    Slide 15 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Typical Application of Supports in a Vertical Run
    • • A cable hanger elbow is used to suspend cables in long vertical runs.
    • • The weight of the suspended cable cannot exceed the manufacturer’s maximum allowable cable tension.
  15. 2.0.0 – 2.13.1

    Slide 16 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Fabricating a Cable Tray Offset with Swivel Plates
    • • Types of splice plates include vertical, horizontal, and expansion plates.
    • • Vertical adjustment splice plates are used to change the elevation in a run of cable tray. They are created using four swivel plates, as shown here.
  16. 2.0.0 – 2.13.1

    Slide 17 - 2.0.0 – 2.13.1

    • Cable Tray 26207-14
    • Expansion Joint and Splice Plates
    • • Expansion joints allow for tray expansion and contraction due to temperature changes.
    • • Barrier strips can be used to isolate electrical circuits.
    • Performance Task
    • This session will conclude with trainees practicing joining cable tray sections.
  17. 3.0.0 – 3.5.0

    Slide 18 - 3.0.0 – 3.5.0

    • Cable Tray 26207-14
    • Cable Tray Support
    • • Cable tray support systems include trapeze mounting, direct rod suspension, wall mounting, center hung support, and pipe rack mounting.
    • • Trapeze mounting uses threaded rods to support a steel channel beneath the cable tray.
  18. 3.0.0 – 3.5.0

    Slide 19 - 3.0.0 – 3.5.0

    • Cable Tray 26207-14
    • Alternate Ways to Hang Cable Tray
    • Next Session…
    • Center Rail Cable Tray Systems
  19. 4.0.0

    Slide 20 - 4.0.0

    • Cable Tray 26207-14
    • Center Rail Cable Tray Systems
    • • Center rail cable tray systems have open sides that provide easy access for cable additions or changes.
    • • This type of cable tray system is typically used in light-duty applications.
  20. 5.0.0 – 6.3.0

    Slide 21 - 5.0.0 – 6.3.0

    • Cable Tray 26207-14
    • NEC® Requirements; Cable Installation
  21. 5.0.0 – 6.3.0

    Slide 22 - 5.0.0 – 6.3.0

    • Cable Tray 26207-14
    • NEC® Regulations Governing Cable Tray Construction and Installation
  22. 5.0.0 – 6.3.0

    Slide 23 - 5.0.0 – 6.3.0

    • Cable Tray 26207-14
    • NEC® Regulations Governing Cable Tray Grounding
  23. 5.0.0 – 6.3.0

    Slide 24 - 5.0.0 – 6.3.0

    • Cable Tray 26207-14
    • What’s wrong with this picture?
  24. 7.0.0 – 9.0.0

    Slide 25 - 7.0.0 – 9.0.0

    • Cable Tray 26207-14
    • Cable Tray Drawings; Pulling Cable in Tray Systems; Safety
    • Cable tray systems are carefully engineered systems and must be installed per the specifications and working drawings.
    • Performance Task
    • This session will conclude with trainees practicing preparing generating a list of materials for a cable tray layout.
    • Next Session…
    • Wrap Up
  25. Wrap Up

    Slide 26 - Wrap Up

    • 3-2-1
    • 3 – Write 3 important things learned during class
    • 2 – Write 2 questions you have about the material
    • 1 – Write 1 thought you had about the material
    • Cable Tray 26207-14
  26. Next Session…

    Slide 27 - Next Session…

    • MODULE EXAM
    • Review the complete module to prepare for the module exam. Complete the Module Review as a study aid.
    • Cable Tray 26207-14