Module 4: Electrical and Auxiliary Systems

electrical plans

details of electrical systems and installations in a construction project

power supply and circuitry, electrical outlets, equipment that will require power, and lighting fixtures

auxiliary systems

details on communication systems (telephones, intercommunication devices, public address systems, radio and TV equipment, CATV and radio distribution systems) and also security systems

How are electrical plans shown?

diagrammatically, using upsized symbols

circuit

a closed path in which electrons from a voltage or current source flow

power; symbol and SI unit

the rate at which electrical energy is transferred by a circuit; P, watt (W)

voltage; symbol and SI unit

electromotive force or pressure that causes electrons to flow; V, volt (V)

current; symbol and SI unit

the flow of an electric charge through a conductor; I, ampere (A)

resistance; symbol and SI unit

the opposition to the passage of an electric current; R, ohm (Ω)

inductance; symbol and SI unit

property of a conductor by which a change in current flowing through it induces a voltage in both the conductor itself and in any nearby conductors; L, henry (H)

capacitance; symbol and SI unit

ability of a body to store an electrical charge; C, farad (F)

Ohm’s Law

V = IR

Power formula

P = VI

alternating current

electric current that reverses its direction many times a second at regular intervals

direct current

steady-state electric currentthat flows in only one direction

power delivered to buildings through transmission lines: AC or DC?

AC

current from batteries; AC or DC?

DC

ampacity; short for?

the current, in A, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating; short for ampere capacity

rating

the voltage at which an appliance or electrical element is designed to work and the current consumption at that voltage

power rating

rating of an appliance in terms of the power it consumes

service entrance

connection between the terminals of the service equipment and a point outside the building

service drop

the overhead service conductors from the last pole or other aerial support to and including the splices, if any, connecting to the service-entrance conductors at the building

service lateral

underground service conductors between the street main and the first point of connection to the service-entrance conductors in a terminal box or meter or other enclosure

When there is no terminal box, meter, or other enclosure, what is considered the point of connection of a service lateral to a building?

point of entrance of the service conductors into the building

service equipment

the necessary equipment connected to the load end of service conductors to a building, intended to constitute the main control and cutoff of the supply

What does service equipment consist of?

circuit breaker/s or switch/es and fuse/s

service meter / metering equipment

device to measure energy use

overcurrent protective device

device that ensures that the rated current of the equipment or the ampacity of conductors is not exceeded; includes fuse and circuit breakers

fuse

overcurrent protective device with a circuit-opening fusible part that is heated and severed by the passage of overcurrent through it

How to restore service when fuse is severed?

replace with a similar fuse of the same size and rating after correcting the cause of failure

types of fuse

1. controlled vented power fuse

2. expulsion fuse unit

3. vented power fuse

4. nonvented power fuse

5. power fuse unit

controlled vented power fuse

a fuse with provision for controlling discharge circuit interruption such that no solid material may be exhausted into the surrounding atmosphere

vented power fuse

a fuse with provision for the escape of arc gases, liquids, or solid particles to the surrounding atmosphere during circuit interruption

nonvented power fuse

fuse without intentional provision for the escape of arc gases, liquids, or solid particles to the atmosphere during circuit interruption

expulsion fuse unit

a vented fuse unit in which the expulsion effect of gases produced by the arc and lining of the fuseholder, either alone or aided by a spring, extinguishes the arc

power fuse unit

vented, nonvented, or controlled vented fuse unit in which the arc is extinguished by being drawn through solid, granular, or liquid material, either alone or aided by a spring

circuit breaker

a device designed to open and close a circuit manually and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating

types of circuit breakers

1. adjustable

2. nonadjustable

3. instantaneous trip

4. inverse time

adjustable circuit breaker

circuit breaker that can be set to trip at various values of current, time, or both, within a predetermined range

nonadjustable circuit breaker

circuit breaker that cannot be adjusted to alter the value of the current at which it will trip or the time required for its operation

instantaneous trip circuit breaker

circuit breaker with no delay purposely introduced in the tripping action

inverse time circuit breaker

circuit breaker where there is a purposely introduced delay in the tripping action; the delay decreases as the magnitude of the current increases

ground

a conducting connection, whether intentional or accidental, between an electrical circuit/equipment and conducting body (e.g., the earth)

What is grounding done for?

to prevent the buildup of voltages that may result in undue hazards to connected equipment or people

panelboard

a single panel or a group of panel units, including buses and automatic overcurrent devices, with or without switches, for the control of light, heat, or power circuits

only accessible from the front, placed in a cabinet/cutout box, and usually mounted on walls

load center

industry term for panelboards used in residential or light commercial applications

switchboard

large single panel, frame, or assembly of panels, which switches, overcurrent and other protective devices, buses, and usually instrument are mounted on the face, back, or both on

accessible from the rear and front, not intended to be installed in cabinets, freestanding

conductor

any material where electric current can flow freely

other term used to refer to conductors

wiring

most common conductors

copper and aluminum wire

branch circuit

circuit conductors between the final overcurrent device protecting the circuit and the outlets

feeder

all circuit conductors between the service equipment, the source of a separately derived system or other power supply source, and the final branch-circuit overcurrent device

raceway

enclosed channel of metallic or nonmetallic materials designed for holding wires, cables, or busbars, with additional functions as permitted in the Philippine Electrical Code

switch

any device used to interrupt the flow of electrons in a circuit

When a switch is “closed,” it is ________; “open",” it is _______

completely on; completely off

types of switches

1. one-way or single-pole switch

2. two-way or double-pole switch

3. pushbutton switch

4. selector switch

5. disconnecting/isolating switch (disconnector/isolator)

6. interrupter switch

7. regulator bypass switch

one-way or single-pole switch

most common type of switch, used to control devices from a single location

two-way or double-pole switch

generally used in industrial applications, used to control device/equipment from more than once location

pushbutton switch

operated with a button that is pressed and released, most have internal spring mechanism returning the button to its unpressed position for momentary operation

selector switch

operated with a rotary knob or lever to select one or more position (e.g., electric fans)

disconnecting/isolating switch (disconnector/isolator)

mechanical switching device used for isolating a circuit or equipment from a source of power

interrupter switch

switch capable of making, carrying, and interrupting specified currents

regulator bypass switch

a specific or combination of devices designed to bypass a regulator

lighting fixture

any electrical device that provides illumination

luminaire

complete lighting unit consisting of a lamp or lamps, and the parts designed to distribute the light, position and protect the lamps and ballast, and connect the lamps to the power supply

outlet

point at the wiring system at which current is taken to supply utilization equipment

power outlet

enclosed assembly that may include receptacles, circuit breakers, fuseholders, fused switches, buses, and watt-hour meter mounting means

intended to supply and control power in vehicles and mobile homes, or for mobile or temporarily installed equipment

receptacle outlet

outlet where one or more receptacles are installed

receptacle

a contact device installed at the outlet for the connection of an attachment plug

emergency power systems

provide automatic backup power during normal power loss

standby power systems

provide automatic backup power during normal power loss, but has 60 seconds to engage

raintight

constructed or protected so that exposure to rain will not result in entrance of water

rainproof

constructed, protected, or treated to prevent rain from interfering with the successful operation of the appratus

watertight

constructed so that moisture will not enter the enclosure

weatherproof

constructed or protected so that exposure to weather will not interfere with successful operation

When can rainproof, raintight, or watertight equipment fulfill the requirements of weatherproof?

when varying weather conditions other than wetness (e.g., snow, ice, dust, temperature extremes) are not a factor

Philippine Electrical Code

governs the design of electrical and auxiliary components of construction projects in the Philippines

when the PEC was most recently updated

2017

What is not within the scope of the PEC?

railway rolling stock, aircraft, and automotive vehicles

chapters of PEC

1. general

2. wiring and protection

3. wiring methods and materials

4. equipment for general use

5. special occupancies

6. special equipment

7. special conditions

8. communication systems

allowable paper sizes for electrical plans

1. 760 × 1000 mm

2. 600 × 900 mm

3. 500 × 760 mm

4. A3, but only if the floor area does not exceed 50 m2 and the total load does not exceed 3680 VA

title block inclusions

1. title of the sheet, sheet number

2. name and location of the project

3. name, signature, and address of the owner

4. name, signature, and seal of Electrical Engineer with PRC license number, PTR number, and TIN

5. scale used

6. date drawn

other information required in electrical plan

1. location and site plans

2. legend or symbols

3. general notes and specifications

4. electrical layout

5. schedule of loads

6. design analysis

7. one line diagram

content of electrical layout

1. plan for power

2. plan for lighting and receptacle outlets

3. plan for fire alarm circuits

4. plan for auxiliary systems

types of loads featured in schedule of loads

1. motor loads

2. lighting and receptacle loads

3. other loads

content of one line diagram

1. lighting and receptacle outlet loads

2. motor loads

3. feeders and sub-feeders

4. load center

content of general notes

1. nature of the electrical service (number of phases and wires, voltage and frequencies)

2. type of wiring

3. special equipment

4. system/method of grounding

5. type and rating of main disconnecting means, overcurrent protection, and branch circuit wiring

6. clearances of service drop, burial depth for service lateral, mounting height and clearance for service equipment, mounting height and clearance for kWh meter