Electrical Systems In A Building

BASIC MECHANICAL ENGINEERING ELECTRICAL SYSTEMS IN A BUILDING

GROUP # 5 GASPI, SYDNEY NATHALIE F. POTENCIANO, ANGELA MAY D. STA. MARIA, JUVIE MARIZTEL M. TAYER, KRIS LORRAINE G.

ENGR. A.G. HICARO

Part One: Introduction and History In 1831, the British scientist Michael Faraday discovered the basic principles of electricity generation. Franklin observed that he could induce electric current by moving magnets through coils of copper wire. The process of Faraday is used in today’s modern power production. In the era of modern power plants, we generated electricity by coal in the United States than any other fuel source. Other sources of electricity are: hydroelectric powerplants, natural gas, nuclear powerplants. Thomas Edison, one of the pioneers of electricity, work on electricity in the 1870s and brought the incandescent electric light bulb for the common use in that same year. The electric systems by Edison were elementary at today’s time.

Part Two: Basic Electrical Techniques Electricity is a physical phenomenon associated with stationary or moving electrons and protons. These electrons create charges which may be harnessed to do work. All electric devices are harnessing the movement of electrons to do work. The electrons create charges namely: voltage, current and resistance. Voltage is defined as the difference in electrical charge between two points in a circuit expressed in volts. Current is the rate of the flow of electricity through a conductor. We define voltage as the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage. Voltage, current, resistance triangle

Part 3. Understanding Drawing Symbols and Reading Electrical Blueprints Symbol

Family

Symbol

Family

Actuators Electrical control

Electrical attenuator

Adaptability Variability

Electrical boxes Conduit

Alarm systems Security systems

Electrical currents

Antennas Aerials

Electrical filters

Home appliances Residential

Electrical motors

Audio & Video

Electrical power generator

Capacitors

Electrical transformers

Circuits, blocks, stages...

Electrical waveforms Electrical signals

Symbol

Coils Inductors

Ferric cores Ferrites

Connectors, sockets, plugs...

Forces, motions and flows

Digital Electronic

Fuses Electrical protection

Diodes

Heat sources Thermal generators

Effects, dependency and radiation

Instrumentation Meters

Family

Symbol

Family

Lamps, light bulbs...

Resistors

Lines, wires, conductors and cables

Sensors Transducers

Material types

Switches

Mechanical couplings

Switches Unifilar representation

Motor starters

Telegraphy Morse code

Operating dependency

Thyristors, Triac and Diac

Phone handset

Transistors

Piezoelectric crystals Oscillator and Resonator

Transistors MOSFET & IGFET

Power converters

Transmission lines Electrical distributions

Power generation station

Vacuum tubes Electron tubes

Power switching devices

Other Electrical & Electronic Symbols

Pushbutton functions Relays Electromagnets

Wall and floor power socket outlet symbols

Single outlet

Duplex outlet

Multiple outlet (number denotes number of sockets)

Duplex outlet with switch

Quad outlet

220-volt outlet

GFCI outlet (more explanation below)

Special Power Outlet (some examples below)

Refrigerator outlet

Clothes washer outlet

Dish washer outlet

Clothes dryer outlet (note 220v)

Range outlet

Floor outlet

GFCI stands for Ground Fault Circuit Interrupter - or circuit breaker for short. These outlets are required in places with water.

General outlets General outlets are where a wire is required to power a fixture where the fixture will be wired in rather than plugged in. The small horizontal line on the left of the circle indicates that the outlet is wall mounted. A circle without the horizontal line indicates that the outlet is mounted in the ceiling.

Light outlet

Blanked (unused) outlet

Fan outlet

Junction box

Lamp holder

Lamp Holder with pull switch

Pull switch symbol

Clock outlet symbol

Power panel

Branch circuit concealed in ceiling or wall

Branch circuit concealed in floor

Branch circuit exposed

Push button symbol

Bell symbol

Buzzer symbol

Thermostat symbol

Circuits and Panels

Smoke detector symbol

Carbon monoxide detector symbol

Part 4. Basics of Electricity Generation

Panic button symbol

Electricity is delivered to consumers through a complex network Electricity is generated at power plants and moves through a complex system, sometimes called the grid, of electricity substations, transformers, and power lines that connect electricity producers and consumers. Most local grids are interconnected for reliability and commercial purposes, forming larger, more dependable networks that enhance the coordination and planning of electricity supply. In the United States, the entire electricity grid consists of hundreds of thousands of miles of high-voltage power lines and millions of miles of low-voltage power lines with distribution transformers that connect thousands of power plants to hundreds of millions of electricity customers all across the country.

The stability of the electricity grid requires the electricity supply to constantly meet electricity demand, which in turn requires coordination of numerous entities that operate different components of the grid. The U.S. electricity grid consists of three large interconnected systems that operate to ensure the stability and reliability of the grid. To ensure coordination of electric system operations, the North American Electric Reliability Corporation developed and enforces mandatory grid reliability standards approved by the Federal Energy Regulatory Commission (FERC). The smart grid The smart grid incorporates digital technology and advanced instrumentation into the traditional electrical system, which enables utilities and customers to receive information from and communicate with the grid. A smarter grid makes the electrical system more reliable and efficient by helping utilities reduce electricity losses and to detect and fix

problems more quickly. The smart grid can help consumers intelligently manage energy use, especially at times when demand reaches significantly high levels or when a reduced energy demand is needed to support system reliability. Smart devices in homes, offices, and factories can inform consumers and their energy management systems of times when an appliance is using relatively higher-priced electricity. This helps consumers, or their intelligent systems, to optimally adjust settings that, when supported by demand reduction incentives or time-of use electricity rates, can lower their energy bills. Smart devices on transmission and distribution lines and at substations allow a utility to more efficiently manage voltage levels and more easily find out where an outage or other problem is on the system. Smart grids can sometimes even remotely correct problems in the electrical distribution system by digitally sending instructions to equipment that can adjust the conditions of the system. Electricity comes from various sources and types of providers The origin of the electricity that consumers purchase varies. Some electric utilities generate all the electricity they sell using just the power plants they own. Other utilities purchase electricity directly from other utilities, power marketers, and independent power producers or from a wholesale market organized by a regional transmission reliability organization. The retail structure of the electricity industry varies from region to region. The company selling you power may be a not-for-profit municipal electric utility; an electric cooperative owned by its members; a private, for-profit electric utility owned by stockholders (often called an investor-owned utility); or in some states, you may purchase electricity through a power marketer. A few federally-owned power authorities—including the Bonneville Power Administration and the Tennessee Valley Authority, among others—also generate, buy, sell, and distribute power. Local electric utilities operate the distribution system that connects consumers with the grid regardless of the source of the electricity. The process of delivering electricity The electricity power plants generate is delivered to customers over transmission and distribution power lines. High-voltage transmission lines, like those that hang between tall metal towers, carry electricity over long distances to where it is needed. Higher voltage electricity is more efficient and less expensive for long distance electricity transmission. Lower voltage electricity is safer for use in homes and businesses. Transformers at substations increase (step up) or reduce (step down) voltages to adjust to the different stages of the journey from the power plant on long distance transmission lines to distribution lines that carry electricity to homes and businesses. U.S. Energy Information Administration. Electricity Explained. December 19, 2016. Retrieved August 31, 2017.

Part 5. Tools and Equipment The electrical apparatus and materials that an electrician is required to install and maintain are different from other building materials. The installation and maintenance of the tools and equipment require the use of special hand-tools. Section I. Interior Wiring This section describes the tools normally used by an Army electrician in interior wiring. Pliers have either insulated or uninsulated handles or gripping with two hinged arms and serrated jaws. Long-nosed pliers are used for close work in panels or boxes. 

Side-cutter pliers are used to cut wire and cable to size. Slip-joint pliers are used to tighten locknuts, small nuts on devices, and conduit bushings and fittings. Round-nosed pliers are used for making screw loops and working in limited space areas.

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Fuse puller is designed to eliminate the danger of pulling and replacing cartridge fuses by hand. It is also used for bending fuse clips, adjusting loose cutout clips, and handling live electrical parts.

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Test probes are attached to the handle and may be used to determine if voltage is present in a circuit.

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Screw drivers come in many sizes and tip shapes with insulated handles. Electricians generally use screwdrivers to attach electrical devices to boxes and attach wires to terminals.

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Wrenches and open-end, closed-end, and socket wrenches are used on hexagonal and square fittings such as machine bolts, hexagon nuts, or conduit unions. Pipe wrenches are used for pipe and conduit work and should not be used where crescent, open-end, closed-end, or socket wrenches can be used. Pipe-wrench construction will not permit application of heavy pressure on square or hexagonal material, and continued misuse of a pipe wrench will deform the teeth on the jaw faces and mar the surface of the material.

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Soldering kit consisting of soldering irons, a blowtorch, alcohol or propane torch, a spool or soil tin-lead wire solder, acid-core solder, and soldering paste. Drilling equipment is used to drill holes in building structures for the passage of conduit or wire in construction.

PART 6.

ENTRY OF ELECTRICITY IN THE BUILDING

There are two ways the main electrical line enters the building. The entry of the main electricity line is from underground connection then is connected to the entry point at either the ground level or into the basement service cable of the building. All the requirements for electric supply connection and other details concerning electricity are found in Philippine Electrical Code, Republic Act 7920.

*Service Drop - the wiring that goes from the nearest transformer to the building’s meter *Service Entry cable - SE cable; wire that goes from your meter to your main breaker panel For Overhead Service:

For Underground Service:

PART 7. DOMESTIC ELECTRICITY SUPPLY Power Distribution in Small Buildings The distribution systems of small commercial or residential buildings are simple. The building’s utility pole will be attached to the transformer which then trim down the voltage from 13.8kV down to 120/240 or 120/208 volts and then passes the electricity to a meter. The meter, owned by the power company, is monitored for energy consumption.

1. From the meter, the power is transmitted into the building. Wires transfer the electricity from the meter to a panel board 2. The panel board will have a main service breaker and a series of circuit breakers, which control the flow of power to various circuits in the building. 3. Each branch circuit will serve a device (some appliances require heavy loads) or a number of devices like convenience outlets or lights. Power Distribution in Large Buildings Large buildings have a much higher electrical consumption than small buildings 1. The building should have and maintain their own step-down transformer. 2. The electricity is then transmitted to switchgear. The role of the switchgear is to distribute electricity safely and efficiently to the various electrical closets throughout the building. 3. Circuit breakers are safety features which allow power to be disrupted whenever maintenance and repair is needed. 4. The electricity will leave the switchgear and travel along a primary feeder or bus. The bus or feeder is a heavy gauge conductor that is capable of carrying high amperage current throughout a building safely and efficiently. 5. The bus or feeder is tapped as needed and a conductor is run to an electric closet, which serves a zone or floor of a building. 6. Each electrical closet will have another step-down transformer 7. That transformer will feed a branch panel, which controls a series of branch circuits that cover a portion of the building. 8. Each branch circuit covers a subset of the electrical needs of the area - for instance: lighting, convenience outlets to a series of rooms, or electricity to a piece of equipment.

SINGLE-PHASE OR THREE-PHASE ELECTRICITY SUPPLY

Single Phase power is a two wire Alternating Current (AC) power circuit. Typically, there’s one power wire and one neutral wire and power flows between the power wire (through the load) and the neutral wire. It is common in households.

Three Phase power is a three wire Alternating Current (AC) power circuit. A 3-phase power arrangement provides 1.732 (the square root of 3) times more power with the same current and provides (7) power circuits. Multistorey buildings and manufacturing plants have three-phase power.

PART 8.

EARTHING OR GROUNDING SYSTEM

Earthing or Grounding is connecting the conductive parts of an electric appliance to the ground/earth. It is done for safety purposes; to prevent electrocution and damage to the appliance. All electrical appliances requiring a current of more than 5 Amperes should be connected to a groundwire. Some appliances have a safety feature like a 3-pin plug, the 3rd pin is the earth pin, no current will flow until the earth pin is in contact with current. Common household appliances that require more than 5A are washing machine (10A), kettle (13 A) and hair dryer (10 A).

The Importance of Earthing or Grounding. The main purpose of earthing is to minimize the danger of electrocution. If there is leakage in the current, the current will direct towards the ground. To avoid this occurrence, the power supply systems and appliances especially those more than 5 Amperes have to be earthed so as to direct the charge to the earth. Basic Needs of Earthing.  

To protect human lives Provide safety to electrical devices and appliances from leakage current.

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To Protect Electric system and buildings from lighting.

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To serve as a return conductor in electric traction system and communication.

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To avoid the risk of fire in electrical installation systems.

POINTS TO BE EARTHED According to IE rules and IEE (Institute of Electrical Engineers) regulations,  

Earth pin of 3-pin lighting plug sockets and 4-pin power plug should be efficiently and permanently earthed. All metal casing or metallic coverings containing or protecting any electric supply line or apparatus such as GI pipes and conduits enclosing VIR or PVC cables, iron clad switches, iron clad distribution fuse boards etc should be earthed (connected to earth).

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The frame of every generator, stationary motors and metallic parts of all transformers used for controlling energy should be earthed by two separate and yet distinct connections with the earth.

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In a dc 3-wire system, the middle conductors should be earthed at the generating station.

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Stay wires that are for overhead lines should be connected to earth by connecting at least one strand to the earth wires.

Components of Earthing System A complete electrical earthing system consists on the following basic components.  

Earth Continuity Conductor Earthing Lead

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Earth Electrode

Methods of Earthing | Types of Earthing Earthing can be done in many ways. The various methods employed in earthing (in house wiring or factory and other connected electrical equipment and machines) are discussed as follows:

1). Plate Earthing: In plate earthing system, buried at least 10ft vertical in the earth, the plate made up of: Copper with dimensions 60cm x 60cm x 3.18mm (i.e. 2ft x 2ft x 1/8 in) Galvanized iron (GI) of dimensions 60cm x 60cm x 6.35 mm (2ft x 2ft x ¼ in) is buried vertical in the earth (earth pit) which should not be less than 3m (10ft) from the ground

level.

2). Pipe/Copper Rod Earthing: A galvanized steel and a perforated pipe or rod is used for pipe earthing. It is the most common type of earthing.

3). Strip or Wire Earthing: In this method of earthing, strip electrodes is buried in a horizontal trenches of a minimum depth of 0.5m.

PART 9.

DUCTS FOR ELECTRICAL DISTRIBUTION

A bus duct (also called busway), in electrical power distribution, is a metal sheet duct having either copper or aluminum bus bars for the purpose of conducting electric current.

Types of Ducts: Duct tube Skirting trunking – used on walls Floor trunking – used in large office spaces Overhead distribution – usually in manufacturing, heavy use of electrical equipment

PART 10 . ELECTRICAL CABLES An electrical cable, or power cable, is used to transmit electrical power. Electrical cables differ in configuration, size and performance. Electrical cables have three (3 parts): conductor, insulation and external protection. Components of Electrical Cables

Types of Insulation: 1. Paper insulated cable 2. PVC Cable 3. Oil-filled insulated cable 4. Compressed gas insulated cable 5. Vulcanized cable Purposes of External Protection: 1. To protect against mechanical damage, fire and other external influences that may cause damage to the cables 2. To prevent undesired bending of cables 3. The cables should be at least 1 meter away from the foundation of the building and at least 0.5 meter away from communication cables.

PART 11. ELECTRICAL INSTALLATIONS 1. Planning and Designing 2. Lay-out of Working Drawings 3. Application to electric supply company (Meralco) for temporary electrical supply 4. Laying conduit for underground supply lines before concreting and completing plinth work 5. Laying of conduits in slabs and beam reinforcement, fixing of fan boxes in slab reinforcement for main supply to consumer units 6. Physical marking of lay-out of wiring in all units/rooms 7. Providing and laying completer wiring 8. Fixing all fittings and fixtures 9. Testing of installations 10. Providing consumer meters 11. Submission of test reports to electric supply company 12. Checking of electrical installation by authorized officer 13. Permanent electric supply connection

PART 12 . BUILDING REQUIREMENTS 1. Accommodation of substation 2. Meter room 3. Switch room 4. Services cable duct 5. Opening and encasement required in floors and walls * Total load requirement should be computed before electrical installation. The type of building should be considered, residential, commercial or industrial. Industrial buildings have the highest load due to machineries and equipment involved.

* Future increase in power consumption should also be anticipated. * The electrical contractor is responsible for the building’s electric installation.

PART 13. EXECUTION 1. Electrical distribution cables should be laid in separate ducts 2. It should be sealed with non-combustible materials 3. There should be separate circuit for water pumps, fire lifts, standby fire pumps, staircase and corridor lighting, blower for pressuring system and other emergency systems. 4. The circuit which contains the emergency functions should be connected to an alternate source of electric supply. 5. The main control room should have air tight fire doors. 6. There should be a service room in the ground floor.

PART 14. TRANSFORMERS, SUBSTATION, DISTRIBUTION BOARD ELECTRICAL TRANSFORMER is a static electrical machine which transforms electrical power from one circuit to another circuit, without changing the frequency. Transformer can increase or decrease the voltage with corresponding decrease or increase in current. It consists of two inductive windings and a laminated steel core. The coils are insulated from each other as well as from the steel core.

Types of transformers Transformers can be classified on different basis, like types of construction, types of cooling etc. (A) On the basis of construction, transformers can be classified into two types as; (i) Core type transformer and (ii) Shell type transformer, which are described below.

(i) Core type transformer In core type transformer, windings are cylindrical former wound, mounted on the core. The cylindrical coils have different layers and each layer is insulated from each other.

Materials like paper, cloth or mica can be used for insulation. Low voltage windings are placed nearer to the core, as they are easier to insulate. (ii) Shell type transformer The coils are former wound and mounted in layers stacked with insulation between them. A shell type transformer may have simple rectangular form (as shown in above fig), or it may have a distributed form. (B) On the basis of their purpose 1. Step up transformer: Voltage increases (with subsequent decrease in current) at secondary. 2. Step down transformer: Voltage decreases (with subsequent increase in current) at secondary. (C) On the basis of type of supply 1. Single phase transformer 2. Three phase transformer (D) On the basis of their use 1. Power transformer: Used in transmission network, high rating 2. Distribution transformer: Used in distribution network, comparatively lower rating than that of power transformers. 3. Instrument transformer: Used in relay and protection purpose in different instruments in industries o

Current transformer (CT)

o

Potential transformer (PT)

(E) On the basis of cooling employed 1. Oil-filled self-cooled type 2. Oil-filled water-cooled type 3. Air blast type (air cooled)

ELECTRICAL SUBSTATIONS are the interface between parts of the distribution systems and transmission systems. These fenced off areas (see Figures 1 and 2) step down the voltage in the transmission lines to one that is suitable for the distribution system. They are also equipped with circuit breakers to protect the distribution system, and can be used to control the flow of current in various directions. They also smoothen and filter voltage fluctuations.

Substations can be categorized by their various functions and roles.

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Step-up substation - These substations raise the voltage from generators (usually at power plants) so that electricity can be transmitted efficiently. For more information on why higher voltages are more efficient for the transmission of power.

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Step-down substation - These facilities lower the voltage from transmission lines to what is known as a subtransmission voltage, which is sometimes used for industrial purposes. Otherwise, the output is then directed to a distribution substation

Distribution substation - These substations further lower the subtransmission voltage to one that can be used to supply most industrial, commercial, and residential needs, with the aid of a distribution transformer before power is finally delivered to the load.[6] These facilities are sometimes located underground.

A distribution board (also known as panelboard, breaker panel, or electric panel) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit in a common enclosure.

REFERENCES Inspection by Bob. Entry of Electrical System. Retrieved September 1, 2017 from http://www.inspectionsbybob.com/vocab-electrical/ The Philippine Electrical Code. . Retrieved September 1, 2017 from http://dsf.edu.ph/wp-content/uploads/2017/04/Philippine-Electrical-Code.pdf Arctoolbox. Electrical Power Systems in Buildings. https://www.archtoolbox.com/materials-systems/electrical/electrical-powersystems.html OEM Panels. 3 Phase Power vs. Single Phase Power. Retrieved September 1, 2017 from http://www.oempanels.com/what-does-single-and-three-phase-power-mean UK Power Networks. Retrieved September 1, 2017 http://www.ukpowernetworks.co.uk/internet/en/help-and-advice/need-help/single-threephase-difference.html Electrical Technology. Earthing and Electrical Grounding Installation | A Complete Guide. Retrieved September 1, 2017 from https://www.electricaltechnology.org/2015/05/earthing-and-electrical-grounding-types-ofearthing.html http://www.free-ed.net/free-ed/Resources/Trades/Elec/ElecConst.asp?iNum=2

Energy Education. Electrical Substation. Retrieved from http://energyeducation.ca/encyclopedia/Electrical_substation Electrical Safety First. Home Appliances: Amps and Watts Ratings Retrieved from http://www.electricalsafetyfirst.org.uk/guides-and-advice/electrical-items/homeappliances-ratings/ Electrical Technology. Different Types of Wiring Systems and Methods of Electrical Wiring. Updated September 09, 2015. Retrieved September 1, 2017 from https://www.electricaltechnology.org/2015/09/types-of-wiring-systems-electrical-wiringmethods.html

Gilani, Natasha. Types of Electrical Cable. Retrieved September 1, 2017 from http://sciencing.com/types-electrical-cable-6495444.html Wikipedia. Distribution board. Retrieved September 1, 2017 from https://en.wikipedia.org/wiki/Distribution_board Daware, Kiran. Electrical Transformer - Basic construction, working and types. Retrieved from http://www.electricaleasy.com/2014/03/electrical-transformerbasic.html Taylor, C. Voltage, Current, Resistance, and Ohm's Law. Retrieved August 31, 2017 from https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law Ohm’s Law and Power. Retrieved August 31, 2017 from http://www.electronicstutorials.ws/dccircuits/dcp_2.html Index of all Electrical Symbols & Electronic Symbols. Retrieved from http://www.electronic-symbols.com/electric-electronic-symbols/electrical-symbols.htm House Plan Helpers. Electric Symbols on Blueprints. Retrieved from http://www.houseplanshelper.com/electric-symbols.html CADPRO. Design and Build Blueprints. Retrieved from https://www.cadpro.com/cadpro-uses/electrical-drawing-blueprints/