2. After going through this module, you are expected to:
1. explain the basic concept of a system of
measurement;
2. perform measurement and calculation about electrical
works; and
3. observe safety precautions in handling electrical
measuring tools and instruments.
3. SYSTEM OF MEASUREMENT
It is defined as a system of related measures that facilitates the
quantification of some particular characteristic. It is a set of units that can be
used to specify anything that can be measured in the layout and installation of
electrical materials.
There are several electrical measuring tools and instruments already
discussed in the previous lesson. In this lesson, we will focus on the commonly
used measurement and calculations in performing layout for electrical
installation works.
Provided on the next slide is the system of measurement used in
measuring distances which focuses on linear measurement which means that
the division per scale is of equal distance to each other, non-linear
measurement on the other hand pertains to the unequal distance of each
division in the scale of a measuring instrument.
4.
5. English Units to Metric Units Equivalent
• 1 inch = 2.54 cm
• 1 yard = 91.44 cm
• 1 foot = 30.48 cm
6. BASIC UNIT CONVERSIONS
The most basic unit conversion from English to Metric and vice versa is
by using the Conversion Factor which uses a fraction or factor written so that
the denominator and numerator are equivalent values with different units as
shown:
7. EXAMPLE: Convert 12 inches to centimeter
Step 1: Write conversion factors for inches and centimeter
OR
Step 2: Choose a conversion factor that
will allow you to cancel the unit of a given
quantity, in the given example, the given
quantity is inches.
Step 3: Operate to successfully convert units.
8. The Multitester
The Multitester/Multimeter or VOM is the best
instrument that can measure voltage, resistance, and
current. It is generally made of two types: the analog
and the digital, in this lesson, you will be guided
about the basic technical know-how about analog
multitester.
9.
10. Resistance Reading
To read the resistance, set the selector switch to the appropriate
Ohmmeter/resistance range to be used, let the negative and positive probe touch
each other and while doing so, adjust the zero-ohm adjustment knob so that the
pointer will point to zero-ohm in the scale before doing any resistance
measurement. The table below shows the value per scale division depending on
the resistance range to be used.
11. The Ohmmeter Scale is located at the topmost scale of the multitester,
depending on where the pointer is deflected or pointed and the range set on the
selector switch, you may now determine the value of the resistance of any
material being tested.
