Module 2: Circuits and Currents & Module 3: Electrical Standards and Practices

Current

the rate of flow of electrons/charge

Current is abbreviated as:

I

Current is measured in:

amperes (A)

One ampere is defined as:

• one coulomb of electrons flowing past a point each second

• (Q/s)

Voltage

• a force that pushes/drives the electrons/charge

• also referred to as electrmotive force or difference in potential

Voltage is abbreviated as

• E, or

• EMF

Voltage is measured in:

Volts (v)

Voltage source will have:

a polarity (negative and positive side)

Current flows from:

negative to positive (changing conventions)

AC/DC

• AC: Alternating current (polarity of source reverses)

• DC: Direct current (polarity is constant)

Alternating Current (AC)

polarity of source reverses

Direct Current (DC)

polarity is constant

Resistance

barriers to the flow of charge

Resistance is abbreviated as

R

Resistance is measured in

ohms (Ω)

Cell

• stores chemical energy

• transfers it to electricial energy

• when a circuit is connected

Battery

when two or more cells are connected together

The cell’s chemical energy is used up by:

pushing a current round a circuit

Electric current

flow of microscopic particles callled electrons flowing through wires and components

In which direction does the current flow?

from the Negative terminal to the Positive terminal of the cell

Parts of a simple circuit

• cell

• switch

• wires

• lamp

To make the circuit:

• these components (cell, switch, wires, lamp)

• are connected together

• with metal connecting wires

When the switch is closed, why does the lamp light up?

Because there is a continuous path of metal for the electric current to flow around

Cell symbol (circuit diagram)

Lamp symbol (circuit diagram)

Switch symbol (circuit diagram)

Wires symbol (circuit diagram)

Circuit diagram components are represented by the following symbols:

Battery symbol (circuit diagram)

Buzzer symbol (circuit diagram)

Ammeter symbol (circuit diagram)

Voltmeter symbol (circuit diagram)

Motor symbol (circuit diagram)

Resistor symbol (circuit diagram)

Variable resistor symbol (circuit diagram)

2 types of electrical circuits

• Series circuits

• Parallel circuits

Series Circuit sample

Series Circuit diagram

Series Circuit

• components are connected end-to-end, one after the other

• makes a simple loop for the current to flow round

• if one bulb blows, it breaks the whole circuit and all the bulbs go out

Parallel Circuit sample

Parallel Circuit diagram

Parallel Circuit

• components are connected side by side

• current has a choice of routes

• if one bulb blows, it will still be a complete circuit therefore the other bulb stays alight

Electric current is measured in ————- using an —————-- connected in series in the circuit

• measured in amps (A)

• using an ammeter

Ammeter in a circuit diagram (Series Circuit)

Ammeter in a circuit diagram (Parallel Circuit)

Measuring current (Series Current)

current is the same at all points in the circuit

Measuring current (Parallel Circuit)

current is shared between the components

The electrical push (voltage) is measured in ————— on a —————-

• measured in volts (V)

• on a voltmeter

Different cells produce——

—-—-different voltages

The bigger the voltage supplied by the cell———-

—-—-the bigger the current

A voltmeter is——-

—-—-connected across the components

Potential Difference

• term usually used by scientists when talking about voltage

Measuring voltage (Series Circuit)

• voltage is shared between the components

Measuring voltage (Parallel Circuit)

• voltage is the same in all parts of the circuit

PEC

Philippine Electrical Code

Philippine Electrical Code content:

• Chapter 1: General

• Chapter 2: Wiring and Protection

• Chapter 3: Wiring Methods and Materials

• Chapter 4: Equipment for General Use

• Chapter 5: Special Occupancies

• Chapter 6: Special Equipment

• Chapter 7: Special Condition

• Chapter 8: Communication System

• Chapter 9: Watercrafts

Two (2) categories of PEC rules

• Mandatory rules

• Advisory rules

Mandatory Rules (PEC rules)

characterized by the use of the word, “SHALL”

Advisory Rules (PEC rules)

• characterized by the use of the word, “SHOULD”

• or are stated as recommendations that which is advised but not required

Objectives of PEC

• Safe Use of Electricity

• Adequacy

Safe Use of Electricity (PEC objectives)

• To establish basic materials quality and electrical work standards

• for the safe use of electricity for light, heat, power, communications, signaling

• and for other purposes

• (PEC 2017 1.0.1.1)

Adequacy (PEC objectives)

• Strict compliance with the provisions of this Code

• will ensure safety in electrical installation and construction,

• but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.

• (PEC 1.0.1.1 B)

INTENTION: (PEC Part I 2017 Edition)

• This Code is intended as a design specification or an instruction manual to qualified persons.

• (PEC 2017 1.0.1.1 C)

Covered scope of PEC 2017 1.0.1.2

covers the installation of electrical conductors, equipment, and raceways, monitoring, signaling, communication conductors and optical fiber cables and raceways installed within or on, to or from:

• Public and private buildings

  • including but not limited to residential, commercial, industrial, institutional, cultural, agricultural, agro-industrial, planned unit development and all other buildings/premises

• Electric generating plants

• Industrial plants

• Transformer stations

• Permanent and temporary substation, etc.

• Airfields

• Railway switchyards

• Yards, carnival, parks, parking and other lots

• Quarries and mines

• Watercraft

• Dockyards

• Trailers

• Mobile homes and recreational vehicles

• Offshore facilities

Not covered scope of PEC 2017 1.0.1.2

• installation in railway, rolling stack, aircraft, or automotive vehicles

• installation of railways for generation, transformation, transmission, or distribution of power used exclusively for operation of rolling stock

The use of PEC is mandated by

• R.A. 7920

• formely R.A. 184

• also known as the new electrical engineering law

R.A. 7920

• new electrical engineering law

• formerly R.A. 184

Referral codes that are mandated by their corresponding laws:

• P.D. 1096 – National Building Code (PEC 2017 1.0.1.4)

• P.D. 1185 – Fire Code of the Philippines

• Structural Code R.A. 7920 – is an act providing for a more responsive and comprehensive regulation for the practice, licensing and registration of electrical engineers and electricians.

P.D. 1096

National Building Code (PEC 2017 1.0.1.4)

P.D. 1185

Fire Code of the Philippines

Structural Code R.A. 7920

• an act providing for a more responsive and comprehensive regulation

• for the practice, licensing and registration

• of electrical engineers and electricians.

Government Authorities who implement PEC:

• Office of the Building Official

• Office of the City Electrician (City Electrical Supervising Engineer)

• Office of the Municipal Electrician (Municipal Electrical Supervising Engineer)

• Regional Office of the DOLE

Scope of the PEC

PEC covers the electric conductors including optical fiber cable and installed within or on, to or from:

• Public and private buildings

• Electrical generating plants

• Temporary and permanent substations

• Industrial plants

• Transformer stations

• Railway switchyards

• Yards, carnival, parking, etc.

• Watercraft

• Dockyards

• Airfields

• Quarries and mines

• Mobile homes, travel trailers and recreational vehicles

• Offshore facilities

• Other premises which requires electrical installation except to those which are done in;

  a) Aircraft

  b) motor vehicles

  c) railway rolling stocks

Permits and Insperction Certificates (PEC 2017 Article 1.2)

• A permit is required before undertaking any electrical installation

• An inspection is also required after which certificate final electrical inspection (CFEI) is issued by the authority.

A permit is required before undertaking any electrical installation

True

An inspection is also required after which certificate final electrical inspection (CFEI) is issued by the authority.

True

A permit is not required ofr:

• the installation of electrical portable equipment rated not more than 1,200 VA.

• reconnection of disconnected service due to non-payment of electric bill or change of occupants for a period of one year.

DPWH form No. 77-001-E

specific application form needed for an electrical permit

Requirement for Electrical Permit

• an application form (DPWH form No. 77-001-E) must be accomplished, signed, and submitted by a duly registered Professional Electrical Engineer.

• if installation does not exceed 20 lighting and/or receptacle outlets or 4000 volt-amperes, 230 volts, the application may be prepared, signed, and submitted by a duly registered electrical engineer or master electrician.

• application shall include the name and signature and seal of the electrical practitioner who will take charge of the installations as well as the signature of the owner or their authorized representative

4 600 mm

• over residential property and driveways,

• and those commercial areas not subject to truck traffic.

5 500 mm

• over public streets, alleys, roads, parking areas subject to truck traffic,

• driveways on other than residential property,

• and other land transversed by vehicles such as cultivated, grazing, forest, and orchard.

Underground Service-Lateral Conductor

• underground service conductor

• between the street main, including any risers at a pole or other structure or from transformers,

• and the first point of any connection to the service-entrance conductors in a terminal box or meter or other enclosure with adequate space, inside or outside the building wall.

Insulation (PEC)

service-lateral conductor shall withstand exposure to atmospheric and other conditions of use without detrimental leakage of current

A grounded conductor shall be permitted to be uninsulated as follows:

a) Bare copper used in a raceway.

b) Bare copper for direct burial where bare copper is judged to be suitable for the soil conditions.

c) Bare copper for direct burial without regard to soil conditions where part of cable assembly identified for underground use.

d) Aluminum or copper-clad aluminum without insulation or covering where part of a cable assembly identified for underground use in a raceway or for direct burial.

Size and Rating (PEC)

• General

• Minimum Size

General (Size and Rating)

Service lateral conductors shall have sufficient ampacity to carry the current for the load and shall have adequate mechanical strength.

Minimum Size

The conductors shall not be smaller than 5.5 mm2copper or 8.0 mm2 aluminum or copper-clad aluminum.

Exception for Size and Rating

For installations to supply only limited loads of a single branch circuit such as small polyphase power, controlled water heaters and the like, they shall not be smaller than 3.5 mm2 copper or 5.0 mm2 aluminum or copper-clad aluminum.

Service

the portion of the supply which extends from the street main duct or transformer to the service switch or switchboard of the building supply.

Service Entrance

the conductor and equipment for delivering energy from the electricity supply system to the wiring system of the premises served.

Types of Service Entrances

• Overhead Service Entrance

• Underground Service Entrance

Overhead service entrance

• most common type of service entrance employed by the power companies

• supplies electricity which is either a 2, 3 or 4-wire connection.

• the overhead service cable between the building property line and the supply point is supplied by electric company to a limit of 30 meters.

Underground service entrance

• consists of a raceway conduit extending from the building to the property line where it is tapped to the main.

• type of cable recommended is the underground service entrance cable commonly referred to as USE.

Service Entrance Conductors

No. of Service-Entrance Conductor Sets Each service drop or lateral shall supply only one set of service-entrance conductors.

Service Entrance Conductors Exceptions

• Buildings with more than one occupancy.

• Where two to six service disconnecting means in a separate enclosures are grouped at one location and supply separate loads from one service drop or lateral.

Service entrance conductors shall be of sufficient size to carry the computed loads.

True

Ungrounded conductors shall not be smaller than:

• 100 A —- For one family dwelling with six or more 2-wire branch circuits.

• 60 A —- For one family dwelling with an initial computed load of 10 kVA above.

• 40 A —- For other loads.

100 A (min. A for ungrounded conductors)

For one family dwelling with six or more 2-wire branch circuits.

60 A (min. A for ungrounded conductors)

For one family dwelling with an initial computed load of 10 KVA above

40 A (min. A for ungrounded conductors)

for other loads