Module 8 - Electrical Layout 50632e

ELECTRICAL LAYOUT WEEK 11 KEVIN D. DUGAY

EE104 – BASIC ELECTRICAL ENGINEERING

OBJECTIVES 1. Describe the general structure of electric system in residential/commercial installation such as the service entrance, electric service metering, grounding and ground fault, circuit safe load, sizing of conductor wires, conduits, overcurrent protective device, and the like

2. Identify various electrical symbols used in an electrical layout 3. Construct a basic/simple lighting and power layout for residential/commercial wiring installations

EE104 – BASIC ELECTRICAL ENGINEERING

Residential and Commercial General Structure of Electric System

EE104 – BASIC ELECTRICAL ENGINEERING

SERVICE BOARD 

It is a single that includes automatic overcurrent devices used for the protection of light, heat, or power circuits.  It is designed to be placed in a cabinet located in or on a wall, partition, or other .

EE104 – BASIC ELECTRICAL ENGINEERING

S

C C

CKT3

C

CKT3

C C

CKT1

S

CKT4

CKT2

EE104 – BASIC ELECTRICAL ENGINEERING

Residential and Commercial General Parts of Electric System Service Entrance  It is a service conductors and equipment for delivering electric energy from the service electric utility to the wiring system of the premises served.  Overhead Service   

This is most often installed in residential wiring. It is less expensive and takes less time to install. Less work in times of trouble and repair EE104 – BASIC ELECTRICAL ENGINEERING

Residential and Commercial General Parts of Electric System Service Entrance  Underground Service 

This is most often installed only as an alternative to an overhead service.  This type of service is more attractive and worth the extra cost and time for the installation.  If a problem arises, the repair procedure requires digging of the ground which is more costly than treating the overhead service. EE104 – BASIC ELECTRICAL ENGINEERING

Residential Service Entrance Requirements (from NEC*) Only power conductors can be attached to the service mast. Cable television wiring or telephone wiring to be attached to the service mast is not allowed.

*National Electric Code (NEC) is a document that establishes minimum safety rules for an electrician to follow when performing electrical installation. EE104 – BASIC ELECTRICAL ENGINEERING

Service Metering (Watt-Hour Meters)  The local electric utility meter department usually install the meter into the meter enclosure once the service entrance is done and the dwelling is ready to receive electrical power.  This meter measures the amount of electrical energy used by the dwelling’s electrical system.

EE104 – BASIC ELECTRICAL ENGINEERING

Grounding (Neutral Conductor) Its connection can be made at any accessible point from the load end of the service drop or service lateral to the terminal strip to which the grounded service conductor is connected at the service disconnecting means. Necessity of Grounding The grounded conductor of an AC service is connected to a grounding electrode system to limit the voltage to ground imposed on the system by lightning, line surges, and unintentional high-voltage crossovers. To stabilize the voltage to ground during normal operations including short circuits. EE104 – BASIC ELECTRICAL ENGINEERING

Branch Circuits  The part of a distribution system consisting of circuit conductors, between the final overcurrent protection and the outlet or load attached.

EE104 – BASIC ELECTRICAL ENGINEERING

Feeders  The conductors between the service equipment and the branchcircuit overcurrent devices are called feeders

EE104 – BASIC ELECTRICAL ENGINEERING

Ground Fault (Overload, Short Circuit) Protective Devices Fuse  It is an overcurrent protection device that opens a circuit when the fusible link is melted away by the extreme heat caused by an overcurrent. Two types are plug fuses and cartridge fuses.

EE104 – BASIC ELECTRICAL ENGINEERING

Circuit Breaker  An automatic device for stopping the flow of current in an electric circuit as a safety measure

EE104 – BASIC ELECTRICAL ENGINEERING

Receptacles  Outlet – is the point on the wing system at which current is taken to supply equipment.  They provide ready access to the electrical system and are defined as a device installed at the outlet for the connection of an attachment plug.

EE104 – BASIC ELECTRICAL ENGINEERING

Special Receptacle Types (Plugs) For Portable Appliances  These are for small appliances like over toaster, coffee maker, television, refrigerator, stereo component, PC and is plug into a 15A and 20A receptacles.

EE104 – BASIC ELECTRICAL ENGINEERING

Special Receptacle Types (Plugs) For Stationary Appliances  These are appliances like electric range, clothe dryer or a room air conditioner.  They usually requires large amounts of current and connected to receptacles that are designed specifically for the amperage and voltage that these appliances need to operate.

EE104 – BASIC ELECTRICAL ENGINEERING

Switches (Snap Switch, Toggle Switch, Light Switch) Switches are devices used to control the various lighting outlets installed in residential and commercial wiring. Single-Pole Switch The most common type of switch used in residential wiring. This switch is used in 120V circuits to control a lighting outlet or outlets from only one location.

EE104 – BASIC ELECTRICAL ENGINEERING

Switches (Snap Switch, Toggle Switch, Light Switch) Double-Pole Switch This switch is used in 240V circuits to control a load from only one location.

It is similar in construction to a single-pole switch but it has four terminal screws instead of two.

EE104 – BASIC ELECTRICAL ENGINEERING

Switches (Snap Switch, Toggle Switch, Light Switch) Three-Way Switch  These are use to control a lighting outlet or outlets from two locations.  It has three terminals.  Two terminals are called the “travelers terminals” which have the same brass color and located directly across from each other on opposite sides.  The other screw terminal is black in color and is called the “common terminal”.  Three-way switches must always be installed in pairs. EE104 – BASIC ELECTRICAL ENGINEERING

Switches (Snap Switch, Toggle Switch, Light Switch) Four-Way Switch  Four-way switches are used in conjunction with three-way switches to allow control of a lighting outlet or outlets from more than two locations.

EE104 – BASIC ELECTRICAL ENGINEERING

Switches (Snap Switch, Toggle Switch, Light Switch) Dimmer Switch  These are used to dim or brighten the light output of a lighting fixture

EE104 – BASIC ELECTRICAL ENGINEERING

Electrical Drawings and Symbols An electrical drawing, a type of technical drawing that shows information about power, lighting, and communication for an engineering or architectural project. Any electrical working drawing consists of "lines, symbols, dimensions, and notations to accurately convey an engineering's design to the workers, who install the electrical system on the job" EE104 – BASIC ELECTRICAL ENGINEERING

Common Architectural Symbols

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Architectural Plan

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Electrical Symbols in an Electrical Drawing 

The electrical drawing must contains many electrical symbols that will show the location and type of electrical equipment required to be installed as part of the electrical system.  Electrical drawing is the most important part of the building plan for an electrician.  The American National Standard Institute (ANSI) provides the standard electrical symbols for use in electrical drawings.  However, plans may have symbols that are not standard. If this is the case, a legend is usually included in the plans which list all the symbols used on the building plans and what they all mean.

EE104 – BASIC ELECTRICAL ENGINEERING

C

CIRCUIT BREAKER

S1 S2 S3 S3W

SINGLE POLE SWITCH

SWP

WEATHER PROOF SWITCH

RANGE CONVENIENCE

DUPLEX SWITCH

WP

TRIPLEX SWITCH

REFRIGERATOR OUTLET

LAMP SOCKET THUMBLER SWITCH

Ref

THREE WAY SWITCH

DUPLEX CONVENIENCE OUTLET

WEATHER-PROOF CONVENINCE OUTLET

ACU

AIRCONDITIONING UNIT OUTLET

CONDUIT RUN

M

SERVICE kWh METER

SWITCH RUN

SERVICE ENTRANCE

HOME RUN BOARD

GROUND BOARD ENTRANCE HEAD SAFETY SWITCH

EE104 – BASIC ELECTRICAL ENGINEERING

ELECTRICAL PLAN

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Residential Design Guidelines 1. The power for lighting is 100VA (if outlet to be served is not specified). 2. The power convenience outlet is 180VA. 3. The maximum distance between convenience outlet is 1.8m (1.5m is preferably used). 4. Wall switches shall be located on the lock side of doors. 5. Lighting outlet shall be separated from convenience outlet to avoid flickering of lamps. 6. Wires and conductors intended for continuous duty shall be loaded not more than 80% of the ampacities.

EE104 – BASIC ELECTRICAL ENGINEERING

Residential Design Guidelines 7. The maximum ampere rating of the branch circuit over current protective device for lighting , small appliances load and similar branch circuit shall be equal to the ampacity of the branch circuit conductor. However, if there no standard size of overcurrent protective device that corresponds to the ampacity of the branch circuit conductor, the next higher standard size may be used. 8. The maximum ampacity of the motor branch circuit conductor shall be 125% of the full load current of the motor. 9. The maximum ampere rating of the motor branch circuit conductor shall be the sum of the full load current of the motors in the group plus 25% of the full load current of the largest motor of all. EE104 – BASIC ELECTRICAL ENGINEERING

Commonly given size of conductor wire AWG

mm2

Ampacity (Amp)

14

2

15

12

3.5

20

10

5.5

30

8

8

40

6

14

55

4

22

70

2

30

95

1

38

110

0

50

125

EE104 – BASIC ELECTRICAL ENGINEERING

SAMPLE ELECTRICAL PLANS

EE104 – BASIC ELECTRICAL ENGINEERING

SAMPLE ELECTRICAL PLANS

EE104 – BASIC ELECTRICAL ENGINEERING

SAMPLE ELECTRICAL PLANS

EE104 – BASIC ELECTRICAL ENGINEERING

Electrical Wiring and Layout

EE104 – BASIC ELECTRICAL ENGINEERING

END OF SESSION