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CHAPTER 10 The Service Entrance Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. List the components of the.

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Presentation on theme: "CHAPTER 10 The Service Entrance Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. List the components of the."— Presentation transcript:

1

2 CHAPTER 10 The Service Entrance

3 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. List the components of the service entrance. List service drop clearances specified in the NEC. List eight basic guidelines when locating a residential service entrance. Calculate the size of service entrance needed based on the power needs of the dwelling. Select proper conductors and components for the service entrance. Objectives

4 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Size and install conductors between the meter socket, main disconnect, and service panel. Provide proper grounding for a service entrance. Explain the purpose of a step-down transformer and indicate where it is used. Objectives (cont.)

5 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Service Entrance All conductors, devices, and fittings that carry electricity from power company’s transformer to the consumer Service entrance components: –Service entrance conductors –Meter socket, pan, or enclosure –Service entrance panel –Grounding system –Fittings, fasteners, and hardware

6 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Service Entrance Location Service drop—Overhead service entrance conductors (OSHA)

7 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Service Entrance Location (cont.) Service lateral—Buried service entrance conductors (Goodheart-Willcox Publisher)

8 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Selecting Service Entrance Location Underground service conductors installed in a straight line Service conductors should be kept as short as practical to minimize voltage drop Service conductors must enter building as near as possible to the service panel Service disconnect must be at or near point of entry

9 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Selecting Service Entrance Location (cont.) Service panel must be located in a central and accessible area Service equipment must be protected from physical damage, water, and dust Service equipment cannot be placed in bathrooms, storerooms, closets, or damp basements

10 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Number of Services Generally, a structure can have only one service Some exceptions: –To supply fire pump or emergency system –To supply a large load demand –Large structures –Service from a generator or solar photovoltaic source –Multiple voltage/phase requirements

11 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Service Disconnects For multiple-occupancy buildings, a maximum of six disconnects can be connected to a single service drop or lateral (Goodheart-Willcox Publisher)

12 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Sizing Service Entrance Conductors Copyright © 2013 NFPA

13 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Service Drop Service drop mast Insulator Service head Drip loop Meter socket Meter (Goodheart-Willcox Publisher)

14 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Temporary Wiring Provides electrical power during construction (Goodheart-Willcox Publisher)

15 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Temporary Wiring (cont.) Installation requirements: –Locate in a safe place –Keep conductors overhead if possible –All receptacles require GFCI protection –Protect wiring from physical damage –Lamps require protective covers –Weatherproof housings required when exposed to weather –Inspect frequently

16 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Service Disconnect Service equipment must include a disconnect that disconnects service from building’s wiring system Common types: –Main disconnect switch –Main circuit breaker in service panel

17 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Service Grounding Grounded (neutral) service conductor connected to neutral bus bar in service panel Neutral bus bar is connected to grounding bus bar Grounding bus bar is connected to grounding electrode

18 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Grounding Electrode Conductor Connects grounding bus bar in service panel to grounding electrode (Goodheart-Willcox Publisher)

19 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Above-Roof Clearances (OSHA)

20 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Above-Grade Clearances (Goodheart-Willcox Publisher)

21 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Building Opening Clearances (Goodheart-Willcox Publisher)

22 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Transformers Convert voltage and current Primary winding Secondary winding (Goodheart-Willcox Publisher)

23 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Transformer Equations

24 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Transformer Example Primary: 12 V, 20 A Secondary: 120 V Find secondary current

25 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Transformer Types Step-up transformer—Voltage increases from primary to secondary Step-down transformer—Voltage decreases from primary to secondary

26 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Phases Single-phase Two-phase Three-phase (Goodheart-Willcox Publisher)

27 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Single-Phase, Three-Wire System (Goodheart-Willcox Publisher)

28 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Three-Phase, Four-Wire Wye System (Goodheart-Willcox Publisher)

29 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Three-Phase, Four-Wire Delta System (Goodheart-Willcox Publisher)


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