Selection of Electric Wire Using Measuring and Testing Instruments

Experiment No.: 2

Experiment Name:

Select the Electric Wire Using Measuring and Testing Instruments for Particular Applications

Objective:

To identify, measure, test, and select the appropriate electric wire for different electrical applications using measuring and testing instruments.

Theory:

The correct selection of electric wire is essential for the safe and efficient operation of any electrical installation. An undersized wire may overheat, cause voltage drop, or even lead to fire hazards. Therefore, before using a wire, its size, continuity, resistance, and insulation condition should be verified.

The conductor diameter is measured using a SWG Measurement Tool, electrical continuity is checked with a Digital Multimeter, and insulation quality is tested using a Megger (Insulation Tester).

The cross-sectional area of a solid conductor is calculated by:

$A=\frac{\pi d^2}{4}$ A=4πd2

Where:

$A$ = Cross-sectional area (mm²)
$d$ = Diameter of the conductor (mm)

Instruments Used:

Instrument	Purpose
SWG Measurement Tool	Measures conductor diameter
Digital Multimeter	Checks continuity and resistance
Hand-driven Megger (500 V)	Tests insulation resistance

Wire Selection Chart:

Application	Recommended Wire Size
LED Light	1.0 mm²
Fan	1.5 mm²
6A Socket	1.5 mm²
16A Socket	2.5 mm²
Geyser (3000 W)	4.0 mm²

Procedure:

Switch OFF the power supply before handling any wire.
Remove a small portion of insulation using a wire stripper.
Measure the conductor diameter with a SWG (Standard Wire Guage) Measurement Tool.
Calculate the cross-sectional area if required.
Set the Digital Multimeter to Continuity Mode and test the wire.
Measure resistance if necessary.
Use a 500 V Megger to check insulation resistance.
Compare the measured wire size with the required application.
Select the suitable wire and record the observations.

Circuit Diagram for Continuity Test:

Measurement of Wire Diameter using SWG:

Circuit Diagram for Insulation Resistance Test:

Observation Table:

Wire Size	Measured Diameter	SWG	Continuity	Insulation	Suitable Application
1.0 mm²	1.13 mm	19	Pass	Good	Lighting
1.5 mm²	1.38 mm	17	Pass	Good	Fan
2.5 mm²	1.78 mm	14	Pass	Good	Socket
4.0 mm²	2.26 mm	12	Pass	Good	Heavy Load

Precautions:

Ensure the circuit is de-energized before testing.
Never use a Vernier Caliper on a live conductor.
Discharge the cable before using a Megger.
Use insulated tools and wear safety gloves.
Replace damaged or poorly insulated wires immediately.

Conclusion:

The electric wires were successfully measured and tested using a SWG Measurement Tool, Digital Multimeter, and Megger. Based on the measured size and test results, the appropriate wire for each electrical application was selected.