What is Earthing: Definition and 39 Discussions

In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth.
Electrical circuits may be connected to ground for several reasons. Exposed conductive parts of electrical equipment are connected to ground, so that failures of internal insulation which create dangerous voltages on the parts which could be a shock hazard will trigger protective mechanisms in the circuit such as fuses or circuit breakers which turn off the power. In electric power distribution systems, a protective earth (PE) conductor is an essential part of the safety provided by the earthing system.
Connection to ground also limits the build-up of static electricity when handling flammable products or electrostatic-sensitive devices. In some telegraph and power transmission circuits, the ground itself can be used as one conductor of the circuit, saving the cost of installing a separate return conductor (see single-wire earth return).
For measurement purposes, the Earth serves as a (reasonably) constant potential reference against which other potentials can be measured. An electrical ground system should have an appropriate current-carrying capability to serve as an adequate zero-voltage reference level. In electronic circuit theory, a "ground" is usually idealized as an infinite source or sink for charge, which can absorb an unlimited amount of current without changing its potential. Where a real ground connection has a significant resistance, the approximation of zero potential is no longer valid. Stray voltages or earth potential rise effects will occur, which may create noise in signals or produce an electric shock hazard if large enough.
The use of the term ground (or earth) is so common in electrical and electronics applications that circuits in portable electronic devices such as cell phones and media players as well as circuits in vehicles may be spoken of as having a "ground" connection without any actual connection to the Earth, despite "common" being a more appropriate term for such a connection. This is usually a large conductor attached to one side of the power supply (such as the "ground plane" on a printed circuit board) which serves as the common return path for current from many different components in the circuit.

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  1. A

    B Can charges move without a field? How charges redistribute without it?

    So from Gauss theorem, electric field at any point inside a uniformly charged sphereical shell is zero. Thus there is no electrostatic force on the inner sphere. From what I have learnt, a field is necessary to move charges. But in this case the inner sphere acquires a charge q without any...
  2. H

    It's interesting to know such amazing stuff

    I was searching for a homework based on earthing. I read a conversation about it. It felt so amazing. So I thought I should sign up too.
  3. G

    Asymmetrical grounding of a 3 phase motor being run on a 1 phase supply

    A single phase, 240V AC supply is used to power the 3 phase motor on my milling machine. A VFD is used to generate the 3 phases required, along with the other benefits such as overload/overvoltage protection, soft start, braking, speed control, reverse, etc. The VFD has an inbuilt EMC filter...
  4. Wrichik Basu

    Investigating a faulty earthing in our house

    We are facing a severe earthing problem. In our house, the potential difference (PD) between neutral and earth is ## 50 - 60 ~\mathrm{VAC},## which should normally be ##< 2~\mathrm{VAC}## if earth is properly connected. I determined this with my multimeter after some appliances were giving...
  5. V

    How does the electroscope lose electrons to the Earth?

    I get step 1, in which due to electrostatic induction the top part of electroscope gets positively charged while the leaves of electroscope become negatively charged. Now if we Earth the positively charged end of electroscope as shown in step 2, then electrons must flow from Earth to...
  6. S

    Charge on two spheres related to Earthing

    Before grounding (left picture), X will be positively charged and Y will be negatively charge. After grounding, I think electrons from Earth will flow to sphere Y and then move to sphere X so X will be neutral and Y will be negatively charged (answer C). But the answer key is D. Why? Thanks
  7. I

    Calculating Short Circuit Current: Tips & Advice

    Good evening to everyone! I'm pretty new in this kind of job, so every help or advice will be helpfull and I will appreciate it. I know that short circuit current from picture in attachment depends on impedance and reactance of Source MV, transformer example (10kV/0.4kV) and cables. So if I...
  8. Brilli

    Charge Flow in Earthed Conducting Shell with Non-Symmetric Configuration

    Homework Statement Consider a thin conducting shell of radius r carrying total charge q. Two point charges q and 2q are placed on the points A and B which are at the distances 0.5r and 2r from centre of the shell respectively. If the shell is earthed how much charge flows from to the earth...
  9. Wrichik Basu

    How does lightning affect appliances with no Earthing?

    It is not very uncommon for appliances to be affected when lightning strikes nearby. This mainly occurs because there is a tendency for the lightning to travel up the earthing wire, thereby damaging the appliance through a high power surge (at least that's what I had learnt). Some days back...
  10. Sunanda

    What is the potential of plate B with respect to infinity?

    I have two isolated plates A and B, kept parallel to each other. Now I give charge +Q to the plate A, it will redistribute itself as +Q/2 on the outer plate A and + Q/2 on the inner plate A. Right? Now this will induce charge -Q/2 on the inner plate B and +Q/2 charge on the outer plate B...
  11. cnh1995

    Earthing in Electrical Systems

    I have a few questions about earthing in electrical systems. 1) How can Earth be used as a "conductor"? I googled its resistance and it turns out that Earth resistance is not that large and it can be reliably used as a conductor. For example, I read it can be used as a return conductor in single...
  12. Neil Hayes

    Finding the value of a neutral earthing resistor

    Homework Statement An 11 kV motor is fed by cables from a transformer via switchgear, having a phase impedance of 0.3 + j0.3 ohm. The Earth return path to the transformer neutral has a resistance of 0.42 ohm. Determine a suitable value of neutral resistance if the voltage rise at the motor in...
  13. gracy

    Earthing of a System of Parallel Metal Plates

    whenever any plate of system of parallel plates is earthed total charge on outer faces of the plates will become zero .Is it always true?or only in case of system of two plates?
  14. person_random_normal

    Understanding Earthing: Impact on Charged Bodies & Charge Distribution

    I understand earthing as - if we Earth a charged body, its charge distribution changes such that, its potential becomes zero. So now I have a doubt that if we have 2 charged spheres(Q1 , Q2) ,separated by some distance and then if we Earth one of them , then how will the charge distribution...
  15. neduet

    Optimizing Earthing Rods for 132kV Switch Yard: The Right Number and Length

    Hi , friends , how many earthing rods we should use in 132 kv switch yard. grid/mesh earthing system. less number better or should we use as many as we can. ? rods length is 3000mm ? thanks.
  16. neduet

    Earthing and Grounding or Protective Earthing

    1 “earthing” for bonding of equipment and circuits to common plant earth electrode potential, 2 “protective earthing (PE)” when this bonding is required for personal safety provisions 3 “grounding” for interference suppressing bonding of screens, sys- tems with ground level 4. low-impedance...
  17. B

    Understanding Earthing: Risks and Safety in Un-Earthed Energy Networks

    Hi All, First post of many on the forum. On the Subject of earthing I had always been led to believe that electricity would always go to ground (if of course ground was the lower potential) I was talking to someone the other day who was discussing un-earthed transmission systems and live...
  18. S

    Discover the Types of Earthing in Automobiles - Expert Insights and Tips

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > HEY guys ; I want to know the types of EARTHING done in automobile . Anybody having any idea ?
  19. Hardik Batra

    Maximizing Charge Repulsion: Understanding Earthing a Conductor 2

    1)If a negatively charge plastic rod (q=-20 e) is kept near the sphere.( which having net charge is zero.) Then how much negatively charge is repelled at the other end by this plastic rod on sphere. 2) if earthing is made to the sphere (at the other end), then all the charge which is repelled...
  20. Hardik Batra

    Earthing a Conductor: I Have Two Spheres

    I have two sphere. 1) one with free electron, if i connected sphere with the Earth by conducting wire all the free electron will flow to the earth. 2) one with positive charge, if i connected sphere with the Earth by conducting wire then the electron from the Earth will flow to the sphere...
  21. C

    Can a second earthing conductor drive the fault current back?

    i have a TT earthing system and to decrease the resistance of the system I'm connecting the rods in parallel. i have the earthing conductor connected but as a mean of security, I'm thinking of connecting a second earthing conductor from the rod to the main Earth bar. Does this cause a any...
  22. F

    Earthing systems and other things

    I recently started working at ABB as a engineer. I wish someone here could help with some questions: 1) In a single phase IT system, why does the circuit breakers have to be bipolar? I believe it is because of a second fault occurence, but i don't really understand what happens. 2) If you...
  23. andyrk

    Why Does Earthing a Charged Sphere Neutralize Its Charge?

    When we Earth a positively charged sphere, the positive charge of the sphere vanishes. Why does this happen? When we connect two charged bodies doesn't charge redistribute till we get equipotential surface? Now when there is no charge on the sphere means the sphere has 0 potential. So that means...
  24. A

    Grounding / Earthing. What does these lines mean?

    Hello Everyone, I have a 5 ampere weighing equipment & need it to ground properly. It is about 80 feet away from soil point. (Direct wire to the equipment will be used & long term connection is required). Manufacturer says that: "There must be a good third wire ground, preferably to a...
  25. V

    I get shock when I touch Grounding (earthing) wire

    Hello experts. This is a unusual behaviour. I moved to new house, an apartment newly constructed less than a year old. I first noticed shock when I was disammbling my computer , i immediately took out multimeter and tester. First checked with tester, it did not show any symptoms of...
  26. D

    Calculating Earthing Rod/Plate Electrodes: IS3043 & IEEE 80

    how to decide the number of earthing rod or plate electrodes.. What the distance btwen two rod to be maintained in prepairng layout As per IS3043 and IEEE 80..
  27. F

    Do Cable Trays in Sydney Car Parks Require Individual Earthing?

    I am looking at a building with a car park in Sydney. Electrical circuits are run on perforated cable trays at high level. I understand that the trays require earthing, however, I'm trying to determine the extent. The trays are made from galvanized sheet and come in 3 meter lengths and are...
  28. W

    Earthing & Lightening Protection for a Home on a Mountain Top

    G'Day guys, We have been looking around and feel this would be an appropriate forum full of good knowledgeable people to ask a few challenging questions. The missus an I are about to build a house on a mountain top that is the highest peak for at least 1-2 km's (1 mile or more). Obviously...
  29. B

    Grounding vs Earthing: What's the Difference?

    Every circuits needs to be grounded in order for it to work, but when do we need to take into consideration on earthing it, and what is the difference?
  30. D

    Earthing Transformer Size for 5MVA 11KV Transformer | DPV

    dear all, can you please suggest the size of the earthing transformer i should be using on HV for a 5MVA, 11KV Trasformer?? thnx DPV
  31. L

    Earthing resistance calculation

    Hi! I'm interested if there is any free software on the web for the calculation of resistance of complex earthing consisting of several interconnected loops? Thanks!
  32. O

    Earthing: Questions on Circuit Completion & Current Flow

    Hi all, I'm new here, hopefully I've posted this in the right section (it's not homework related). :smile: Ive got a question that has been baffling me. I understand that current travels from high potential to lower potential, generally taking the easiest path (s/c path if it exists)...
  33. J

    What are generator neutral earthing resistances

    what are generator neutral earthing resistances. Are they necessary for small generators? (50 KW 3 phase 120/208v.)
  34. I

    What are the recommended resistances for different levels of earthing pits?

    There are different levels of earthing pits. Like transmission stations, local substations, etc. Can someone specify the resistances of the earthing pits that each of them in level should actually have.
  35. C

    Earthing System: Aircraft & Ships | How To Do It

    How the earthing can done in air craft systems, ships
  36. M

    Do ‘grounding’ and ‘earthing’ mean the same?

    do ‘grounding’ and ‘earthing’ point to a same thing? Is there any difference between them?
  37. J

    Earthing Transformer: Wye vs Zigzag Connection

    :rolleyes: I'm curious if we use a direct wye connection instead of zigzag in case of earthing transformer.. i know that by merely looking if we use wye connection in earthing specially in medium voltage you have to have enough reactance for your exciting voltage.which will cost more in...
  38. S

    Electrons & Earthing: Effects on Neutralization & Earthed Objects

    If protons are neutralized with the electrons, then a group of electrons come close and repel them,if the opposite side of the object is earthed, will they get earthed or just move away somewere in that object? and if the object was large enough would they stop half-way after they stop feeling...
  39. exequor

    Earthing/Grounding Alternatives

    Earthing/Grounding alternatives Ok, in my house there are 220V outlets with 3 pins (earth, live and neutral). the Earth wire is sent to a metal pipe outside which was pounded into the ground. i was thinking of alternative ways to get setup the earthing system. i know that if the Earth wire was...