Presentation is loading. Please wait.

Presentation is loading. Please wait.

4 Wiring Systems. 4 Wiring Systems Objectives Know where to find codes and authorities for an installation. Recognize the marks of the most popular.

Similar presentations

Presentation on theme: "4 Wiring Systems. 4 Wiring Systems Objectives Know where to find codes and authorities for an installation. Recognize the marks of the most popular."— Presentation transcript:


2 4 Wiring Systems

3 Objectives Know where to find codes and authorities for an installation. Recognize the marks of the most popular testing agencies. List the different conductor systems used in residential and light commercial wiring. Explain the basics of conduit bending. Become familiar with the many different types of raceway systems.

4 National Electrical Code (NEC)
Rules, regulations, and criteria for installation of electrical equipment Revised every three years Compliance typically mandated by state or local building codes “Authority having jurisdiction”—person responsible for approving electrical installations

5 Code Alert Article 90 defines what is and is not covered by the NEC
Article 100 provides definitions of essential terms used throughout the NEC Article 110 provides general requirements for electrical installations

6 State and Local Codes All electrical construction governed by state or local building codes Be aware of specific codes based on location and type of construction Codes generally require Licensing Permits Inspection/approval

7 Additional Organizations
Nationally recognized testing laboratories Test materials and equipment Underwriters Laboratories Occupational Safety and Health Administration (OSHA) Agency of US federal government Required safe practices

8 Wiring Systems Wiring system—Wiring and related components used in an electrical system Two primary classifications: Cables Raceways

9 Armored Cable (AC) Also called “BX” Components: Armor (outer covering)
Insulated conductors Bonding strip (for equipment grounding system)

10 Armored Cable (AC) (cont.)
Requires anti-short bushings to protect conductors from sharp edges of armor

11 Armored Cable Connectors

12 Nonmetallic Sheathed Cable (NM)
Also called “Romex”

13 Stripping Nonmetallic Sheathed Cable

14 Service Entrance Cable (SE)
Overhead cable Connects utility company transformer to home’s service panel Underground service entrance cable (USE) Below-grade service connections Underground feeder and branch-circuit cable (UF) Similar to NM but designed for below-grade use

15 Code Alert Typical requirements for cable support
Cable must be supported within 12 of a box Maximum distance between cable supports is 4-6 Always check support requirements for specific cable type being used

16 Raceways Protective tubing installed to house conductors
Conduit—tubing connecting boxes and devices in a wiring system

17 Common Raceway Systems
Electrical metallic tubing (EMT) Electrical nonmetallic tubing (ENT) Rigid metal conduit (RMC) Rigid PVC conduit (PVC) Intermediate metal conduit (IMC) Flexible metal conduit (FMC) Liquidtight flexible metal conduit (LFMC) Surface-mount raceways

18 Electrical Metallic Tubing (EMT)
Also called “thin-wall” conduit Not threaded Tubing serves as equipment grounding conductor—proper connections are critical

19 EMT Connections

20 Cutting Metal Conduit Cutting tools:
Hacksaw Reciprocating saw Pipe cutter After cutting, use reamer, file, or deburring tool to eliminate sharp edges

21 Bending Metal Conduit Field bend—Conduit bend made on the construction site Generally, bending is easier and less costly than using fitting Always use the correct size conduit bender Always know the minimum bend radius allowed by code

22 Stub Bend

23 Back-to-Back Bend

24 Offset Bend

25 Offset Bend (cont.) Preparation Measure distance to obstruction
Measure height of obstruction Use offset bend chart to determine Angle of offset Distance between bends Shrink

26 Offset Bend (cont.) Marking conduit
Add shrink to the distance to the obstruction, and mark conduit at this distance Measure back the distance between bends

27 Offset Bend (cont.)

28 Box Offset

29 Saddle Bend Two 22 1/2 bends and one 45 bend Preparation
Measure height of obstruction Find distance from start of conduit to center of obstruction, then add 3/16 for every inch of obstruction height (for 1/2 conduit). Mark this location (center of bend) On each side of center mark, measure and mark a distance equal to 2 1/2 times the height of the obstruction

30 Saddle Bend (cont.)

31 Electrical Nonmetallic Tubing (ENT)
Often called “smurf tube” or “smurf” Corrugated, flexible plastic Easy to install Cannot be buried or left exposed

32 Rigid Metal Conduit (RMC)
Galvanized pipe, similar to water pipe Threaded connectors and fittings Conduit part of equipment grounding system RMC has thicker walls than EMT has

33 RMC Connectors and Fittings

34 Rigid PVC Conduit (PVC)
Hard plastic conduit Lighter than metal conduit Can be heated and bent Conduit joined to fittings with glue

35 PVC Connections

36 Other Raceway Systems Intermediate metal conduit (IMC)
Walls thicker than EMT and thinner than RMC Flexible metal conduit (FMC) Also called “Greenfield” Similar to armored cable casing Liquidtight Flexible Metal Conduit (LFMC) Similar to FMC with a plastic sheath Surface-mount raceways

Download ppt "4 Wiring Systems. 4 Wiring Systems Objectives Know where to find codes and authorities for an installation. Recognize the marks of the most popular."

Similar presentations

Ads by Google