# Electrical Engineering Questions

Do you know how to measure the earth resistance?

Actually the Earth resistance is measured using “earth resistance meter”. You might have also heard that using megger, but megger is used only for high resistance measurement i.e., in Mega ohms but when considereing upon earth resistance it should not exceed 1ohm so earth resistance meter is required.
In this meter there will be four terminals(E, P1, P2, P3) in which E and P1 will be shorted and connected to the grid or electrode and P2 and P3 are reference electrodes which will be kept on the earth surface on two different locations for taking the reference resistances of the earth.
The meter shows the resistance of the earth. But it is neccessary that it should be below 1ohm.

How to maintain the earthing resistance?

Earthing Resistance can be maintained by adding water,charcoal & salt per month,Not only by adding those three, Its rusted bolt& Nuts must be renewed by new one for every three month,this maintenance should be varied depand upon the climatic conditions, such as in rainy season.Earth pit must be fenced with cement.

What is the difference between grounding and earthing?

In America, Canada etc. word Grounding is used ( GND ) and in rest part of the world including india , word earthing is prefferd.

Generally both are same but in detail when we connect any equipment (i.e. motor, mixture, washing machine or any house hold equipment) with the earth through earth wire its called earthing …. And when we earth any system like star point of generator or transformer is called Grounding.

What is the principle of tubelight? What is the function of starter and choke?

Tubelight works on the principle of electric discharge. Starter act as a switch and choke acts as an inductor. When tubelight is switched on the electricity flows through starter which is actually a capacitor. Sooner the dielectric strength decreases and it gets shorted hence switching of the supply through inductor. During this time the choke stores energy which is appeared across the electrodes of the tubelight and hence helps in ionsation of gas and electric discharge. Starter is connected in parallel to tubelight and choke is in series.