Lesson 2: LO 1. Select Measuring Tools and Instruments and LO 2. Carry Out Measurements and Calculations

Lesson 2
LEARNING OUTCOMES
 LO 1. select measuring tools and instruments; and

 LO 2. carry out measurements and calculations.
Performing Mensuration and Calculation

LEARNING OUTCOME 1
Select Measuring Tools and Instruments.
PERFORMIMG STANDARS
 Measuring tools and instruments are selected/ classified as per object to be

measured on job requirements. 
 Measurements are obtained according to job requirements. 
 Computation of resistance, current, and voltage using Ohms Law are obtained.
DEFINITION OF TERMS
 Amperage (Amps) - a unit of measurement of electrical current flow.

 Ampere - a unit of measurement which describes the amount of electric current
passing a certain point at a particular time.
 Centimeter - hundredth of a meter Inch - a portion of a foot, which is an English
unit of linear measurement.
 Megger - an instrument used to measure the insulation resistance of conductors
or wire. It gives measurement in ohms or meg-ohms.
 Millimeter - one-thousandth of a meter.
 Multi-tester - an electrical measuring instrument used to measure the voltage, the
resistance or the current of a circuit. It is connected either through parallel or
series with the circuit depending on what to measure.
 Ohm - the unit of measurement used to express resistance.
 Ohmmeter - an instrument used to measure resistance in ohms.
 Volt - a unit of measurement of electrical pressure or voltage.
 Voltmeter - an instrument specially designed for measuring voltage.
 Wire Gauge - used to measure the diameter of magnetic wire.
MEASURING TOOLS AND INSTRUMENTS

Measurement is the process or the result of determining the ratio of a physical quantity,
such as a length, time, temperature, etc., to a unit of measurement, such as the meter,
second or degree Celsius. The science of measurement is called metrology. The
English word measurement originates from the Latin mēnsūra and the verbmetiri
through the Middle French mesure.
 Test Light- a pocket size tool used to test the line wire or circuit if there is current
in it.
 Micrometer- used to measure the diameter of wires/conductors in circular mils. It
can measure small and big sizes of wires and cables.
 Wire Gauge- used in determining the size of wires/conductors. The gauge ranges
from 0 to 60 awg (American wire gauge)
 Ruler/foot rule- a measuring tool used to measure length, width and thickness of
short flat object and in sketching straight lines.
 The ruler is the instrument used to rule straight lines and the calibrated
instrument used for determining length called a measure. However, common
usage calls both instruments rulers and the special name straight edge is used
for an unmarked rule.
 Pull-Push Rule - a measuring tool used to measure the length of an object in
centimeter and inches.
 Ammeter - an instrument used to measure the amount of electrical current
intensity in a circuit. The unit of measure is ampere (a). It is connected along or
series to the circuit.
 Voltmeter - an instrument used to measure electrical pressure or voltage of a
circuit. The unit of measure is volt (v). This is connected across or parallel to the
circuit.
 Clamp Ammeter(also called tong-tester)- It is used to measure current flowing in
a conductor. It is clamped or hanged in a conductor.
 Volt-Ohmmeter (VOM) - otherwise called as Multi-tester; is used to measure the
voltage, resistance and current of a circuit. It is connected in parallel or series
with the circuit depending on what to measure.
SYSTEM OF MEASUREMENT
 a set of units which can be used to specify anything can be measured

Common units of measurement used in making layout and installation of
electrical materials:
A. Linear measures B. English units and eac
English system provides the creative way on how people can · 12 inches = foot(ft)
measure by themselves. For example, people measure shorter · 1 foot = 3yard (yd)
distance on the ground with their feet. They measure long distances · 1 yard = 36 inches
by their palms which is equal to a yard. C. Metric units and each
· Inch · 10millimeter (mm) = 1ce
· Yard · 10centimeter = 1decime
· Miles · 10 decimeter = 1meter
Metric system is a decimalized system of measurement. It exists in D. English to metric equ
several variations with different choices of base units. Metric units are · 1 inch = 2.54 cm
widely used around the world for personal, commercial and scientific · 1 foot = 30.48 cm
purpose. · 1 yard = 91.44 cm
· Millimeter
· Centimeter
· Decimeter
· Meter
E. The centimeter graduation
How to read the cm graduation: F. The inch graduation
1. First graduation is .5 mm How to read the inch graduatio
1. First graduation is 1/16
2. Second graduation is 1mm 2. Second graduation is 18
3. Third graduation is 1.5mm 3. Third graduation is 3/16
4. Fourth graduation is 1/4, then follow th
4. Fourth graduation is 2mm
THE MULTITESTER
 Multitester or multimeter is sometimes called the VOM (voltmeter, ohmmeter,

milliammeter). It is the best instrument that can measure voltage, resistance and
current. It is generally made of two types: the analog and the digital.
A. PARTS OF A MULTI TESTER
 RANGE SELECTOR KNOB (Selector switch) makes it possible to select different

functions and range of the meter. POINTER - The needle-shaped rod that moves
over the scale of a meter. It is mechanically connected to the moving coil.
 Adjustment screw - makes it possible to adjust the pointer to the zero position of
the scale.
 SCALE is a series of marking used for reading the value of a quantity.
 Test probe positive (red), negative (black) - used to connect the circuit to the
electrical components being tested.
 Zero-ohm adjustingKnob is used to zero-in the pointer before measuring
resistance.
B. Proper care and maintenance of the multi tester

 Read manual of instructions on how to operate the multi-tester.
 In reading the amount of voltage, always start with the highest range to avoid
reading voltage higher than the tester setting.
 Be sure that the tester is set to the correct range setting: resistance range when
measuring the ohm, voltage range when measuring voltage and ammeter range
when measuring the value of electric current.
 Always check the condition of its battery. Worn out batteries will damage the
internal setting of the tester.
 When the tester is not in used or will be stored, set the selector switch to 1000V
or to OFF position.
 Never drop the tester.
To read the resistance range of the multi-tester, the given table below will be
used. The unit of measurement to be used to determine its resistance is ohm.
Voltage scale

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Lesson 2

 LO 1. select measuring tools and instruments; and

Performing Mensuration and Calculation

 Measuring tools and instruments are selected/ classified as per object to be

 Amperage (Amps) - a unit of measurement of electrical current flow.

MEASURING TOOLS AND INSTRUMENTS

 a set of units which can be used to specify anything can be measured

 Multitester or multimeter is sometimes called the VOM (voltmeter, ohmmeter,

A. PARTS OF A MULTI TESTER

 RANGE SELECTOR KNOB (Selector switch) makes it possible to select different

B. Proper care and maintenance of the multi tester

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