CCENT 360: How to use a Multimeter ?

1.The figure below is the MASTECH Multimetre which I have.
2.AC Voltage is on the right symbol is wave ¬.DC Voltage is straight line -.
3.Among the three connection point in the Electrical socket.
          Top Hole = Earth
          Right Hole = Live (or Ground)
          Left Hole = Neutral

   Energy cannot be created or destroyed but converted from one form to another.

4.What is Earthing and why it is required ?

Electricity flows in a circuit from two points with different electrical potential. If you get

shocked, it’s because you’re touching two things. Typically, these are 1) a live electrical

wire and 2) the ground.

For example, a wire comes loose in an electrical appliance, and contacts the outer enclosure.

A barefoot person touches the appliance, and gets shocked.A measure of safety can be provided

by making sure that anything metal that you might touch has no potential difference with the ground.

This is done by connecting it to the ground with a wire.

Grounding the appliance does not protect against all safety hazards. If you spill water in

the appliance, you could create a small current that fails to trip the breaker, while still

conducting current outside the appliance.

It's an electrical connection between the exposed metallic parts of an electrical appliance or

installation and the earth, regarded to have zero potential.

Very important Point here is that the three point electrical socket may have earthing

but there should be an earthing (or simple a wire ) that connects exposed parts of

the electrical appliance to the Earthing/Ground socket hole.The Electrical wire

connecting the electrical socket to the electrical appliance should have a connection

to the Earthing grounding point.No point if there is proper earthing in the socket

but no connection to that earthing point !!! .

Proper earthing provides an alternative and easy path for leakage or faulty current to flow.

It ensures that any exposed conductive part of the appliance does not reach a dangerous

level of potential or voltage that endangers the user's life.

A proper earthing system should have least electrical resistance, good corrosion resistance(hence

copper is used) and ability of dissipating high faulty current.

5.Set the Voltage to highest on the right which is AC the wave.

Neutral is connected to the power line whereas the ground is physically connected to
the Rod which is usually dig up in the Earth.
The neutral creates the potential difference between the two ends of the line, the existence
of this potential difference is responsible for the flow of current through the line.
In All Ac system a return path for the current is required otherwise the circuit will be
incomplete,that return path is the neutral wire.

http://www.sciencebuddies.org/science-fair-projects/how-to-use-a-multimeter.shtml

https://www.quora.com/Why-is-earthing-necessary-in-electrical-systems