Why ground [earth]

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Our modern Life is Off the Work of Giants

Our modern Life is Off the Work of Giants

tryinghard said:
Curious Minds Have To Know

Q: Why ground [earth] :-?

Why else?
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Article 100 - Ground. The earth NFPA 08'.

Because the basic circuit(s) of AC or DC needs a ground for some form of work to be done, IE it completes the circuit.
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Go to Electricity and magnetism, note all the Giant Laws are there!

Look at Electrical circuits, and read voltage law. "No matter what path you take through an electric circuit, if you return to your starting point you must measure the same voltage, constraining the net change around the loop to be zero. Since voltage is electric potential energy per unit charge, the voltage law can be seen to be a consequence of conservation of energy. "
Thus one needs a ground, yes a battery is shown in diagram. In theroy a battery should be infinite.

As I learned in Physic's (which I really had to work at):rolleyes: The earth's core is a bigger electron draw that we use to help complete a circuit. Granted along with the minerals and elements that compose most materials (some regions don't have a good ground cause of the minerals) that one is grounding to and that sharing of the electrons via the minerals help complete the circuit.

Also note current law and current flow and Flowrate.

If you never taken Physic's this is a great page and if one did a good reference point.

Enjoy
 
250.4

If we were talking about an SWER my answer would be different, but of course we would not be talking LV either.

Roger
 
One reason for confusion over issues with "grounding" is that the term is often applied without a qualifier. It would be nice if we never used the term ground by itself unless were were talking about dirt. I myself have often been guilty of not qualifying what I meant when using the single term ground.

I like to use terms like PE (protective earth), or Equipment Ground conductor or chassis ground.

You often hear "ground" used to describe a dc common return line.

I have also worked with terms like "low noise return, bus or plane" or "low impedance ground" when dealing with noise sensitive equipment.

I think mostly we "ground" for a common reference point. Often different systems with different purposes for their "grounding" compete with one another.

An example is the EGC or chassis ground of equipment required for safety reasons. This can compete with a dc logic common connection inside of the equipment when it is also connected to the chassis. The combination of the two can lead to ground loops. Electrical noise can also use the EGC as a route to carry noise into the dc circuitry.

On top of that add that equipment may incorporate an EMI filter that diverts electrical noise to the chassis -then earth connection. These noise protective capacitors can "leak" 60 hz currents into the interconnected grounding schemes that can result in degraded performance of TVs and stereos.

Grounding can become a very complicated subject when many different interests are being served by act of grounding and or bonding.
 
cadpoint said:
Article 100 - Ground. The earth NFPA 08'.

Because the basic circuit(s) of AC or DC needs a ground for some form of work to be done, IE it completes the circuit.
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Go to Electricity and magnetism, note all the Giant Laws are there!
Click to expand...

cadpoint that?s a useful site! I am really trying to drive a point about grounding (literally as defined in Article 100 and 250-4). Thanks also for pointing out the definition of Ground = ?The earth? in NEC 08, I think most should be able to interpret that one:)

No doubt the premises electrician is loose with this terminology but so are all the related electrical trades.

Because of my real point to press I?ve gota say one certainly can lift the ground electrode conductor at a service disconnect without any effect to the circuitry because it is a non-current carrying conductor and it is used for the purposes as described in 250-4(A)(1). With transformers there can be some issues with re-striking and arcing ground faults of a grounded system that is not bonded but most often, especially with the premises electrician, when talking ?ground? they mean at the service disconnect.
 
ELA said:
One reason for confusion over issues with "grounding" is that the term is often applied without a qualifier. It would be nice if we never used the term ground by itself unless were were talking about dirt?

?Grounding can become a very complicated subject when many different interests are being served by act of grounding and or bonding.
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Ya howdie!, I agree we really need to be specific most often.
 
Ground of Premises Wiring (grounded systems)

Ground of Premises Wiring (grounded systems)

Ground is not needed to complete a circuit, it is not current carrying and it is not needed for short-circuit or ground-fault protection.

Neutral is not ground, grounded conductor is not ground, and these do not need ground for a circuit to function correctly or safely.

Bonding is not ground. Bonding IS extremely important and integral for ground-fault protection though. Bonding creates the effective ground-fault path from conductive items to source needed to enable ground-fault protection. The source is usually the XO of a transformer this XO (neutral/grounded conductor terminal) must bond to the case and equipment to allow a fault path throughout to route to the source ?XO?.

An electrode is not ground. An electrode is described in 250-52 & 250-30(A)(4) and it is the item that directly connects to ground therefore it is most often referred to as ground. An electrode receives a conductor the ?Grounding Electrode Conductor? to bond conductive items, an unbroken GEC does not have to be larger than #4 cu for Ufer/Rod/Pipe or Plate electrodes regardless the size of service entrance conductors or the size of the service disconnect.

Ground is the earth (NEC 08 definition); ground is needed to limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines?as per 250-4(A)(1), it gives these items a route. The best electrode is the one that is installed correctly and remains in place, a few ohms one way or another does not change how it will route lightning. In this light if a better ground is needed then an engineered lightning rod ground system should be installed.

The descriptions really are clear but the word ?grounding? is extremely misused. Technology is a good example of using terminology for specific descriptions and reasons it does so because broad terminology is vague and prone to error, that?s what happens when we misuse the terminology of ground it causes misunderstandings and grief.

That?s it any problems are from incorrect bonding not ground.
 
tryinghard said:
An electrode is not ground. An electrode is described in 250-52 & 250-30(A)(4) and it is the item that directly connects to ground therefore it is most often referred to as ground.
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I think your last post was about the best you've had along these lines, but I would rephrase the point you made I bolded above. IMO, the object most frequently referred to commonly as "ground" is the EGC, not the GE.
 
georgestolz said:
I think your last post was about the best you've had along these lines, but I would rephrase the point you made I bolded above. IMO, the object most frequently referred to commonly as "ground" is the EGC, not the GE.
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I agree, and I also know I?m buckin a headwind regarding terminology. The EGC is bonding but we call it equipment grounding and why not we also say we have a ground fault yet actually these do not go to ground but to source. Thanks George for your input.
 
tryinghard said:
I agree, and I also know I?m buckin a headwind regarding terminology. The EGC is bonding but we call it equipment grounding and why not we also say we have a ground fault yet actually these do not go to ground but to source. Thanks George for your input.
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So for the next cycle we should submit EBC over EGC? and Bonding Fault in place of Ground Fault?

Should someone compile a list of terminology changes?
 
pfalcon said:
So for the next cycle we should submit EBC over EGC? and Bonding Fault in place of Ground Fault?

Should someone compile a list of terminology changes?
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Well, over the last two cycles there have been proposals to accomplish just that - but in the last cycle, they concluded the least confusing thing to do is write "connected to the equipment grounding conductor" 86,000,000 times, as opposed to using the term "bonded".

It was a step in the right direction, but I think the terms should still be changed. However, I don't see a promising future for any proposals suggesting it.
 
If you were to take a simple 240 v single phase service and connect an outlet between one side of the service and the neutral , you would have an active electrical circuit. Same if you were to also add the same to the other side of the 240 v service. The circuits will operate perfectly that way BUT should something short in the circuit(neutral to hot) it would raise havoc with the supplying transformer and the utility company would not be happy. Adding the EARTH ground gives a very low resistance path for any stray current or voltages to follow in some kind of breakdown. The actual bonding of EARTH ground to the neutral of a service serves as a SAFETY . It equalizes the neutral with the "ground" (EARTH). Yes. AC circuits will work without an EARTH ground , but they simply are not safe. Having experience in both electronic circuitry and electric circuitry, there is a vast world of answers to why we do or do not use a GROUND , or more precisely an EQUIPMENT GROUND. Many electronic circuits refer to "ground" but are in all actuality, referring to a DC return path, ie, one that is lower in voltage than the supply path.
Grounding is confusing if not understood exactly what the term means.
 
tryinghard said:
Curious Minds Have To Know

Q: Why ground [earth] :-?
A1: Common reference point?
A2: Because 250-4(A)(1)&(2)

Why else?
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1) because 100 years ago it was someone's bright idea
2) because it saves the utility companies a boatload of money (even though it creates life threatening hazards)
3) because of "voodoo" electrical theory developed over the years from #1 and #2 which have clarified and obfuscated every facet of what's good and bad about #1 and #2 but not fixed it by making the utility companies add one life saving wire to the entire grid
 
Let me throw my thoughts in here solely so I can be corrected if I am wrong. I am not being rude, just trying to learn.

cadpoint said:
Article 100 - Ground. The earth NFPA 08'.
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Based on the above quoted definition of ground, the following statement is not correct, it is misleading, and an old wive's tale that has confused many electricians and muddied the waters of grounding and bonding for the last 100 years.

cadpoint said:
Because the basic circuit(s) of AC or DC needs a ground for some form of work to be done, IE it completes the circuit.
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A flashlight does not require a connection to the earth to work. Electrical circuits on a spacecraft which is halfway to Mars do not require a ground to work. The service on your house does not require a connection to earth to work.

Electrical work can be done without any relation or connection to earth.

For current to flow, all you need is a potential difference and a path which allows current to flow. This could be a solar cell with a wire to a load and another wire back to the opposite side of the solar cell.

cadpoint said:
Thus one needs a ground, yes a battery is shown in diagram.
Click to expand...

I can build a generator which will power a lamp and completely isolate the entire thing from earth. A path through earth is not necessary for a circuit to work.

cadpoint said:
The earth's core is a bigger electron draw that we use to help complete a circuit.
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Incorrect. This is one of the most misunderstood thoughts out there.

Electrons from a voltage source will leave the negative terminal and migrate in a completed path to the positive terminal. There is no need for the earth to play any role in this.

The electrons coming out of a generator do not want to go into the earth. They want to travel toward the opposite side of the power source.

The lights on an airplane will work without ground. (Note that AC voltage will regularly change the polarity of the terminals and the electrons will migrate one way, and then the other way, on and on.

Someone above noted that electronic circuits often use the term "ground" as one side, or perhaps the center point of DC sources. This is a totally different usage of the term than what we as electricians are doing. This has definitely messed things up with our thinking.
 
I would also submit this for your review:

If the only consideration was electrical safety inside a building, I think the safest system would be an ungrounded system with the following:

1. All metallic non-current-carrying items bonded together with a low impedance path

2. A monitor to detect if a current carrying conductor or load came into contact with any non-current-carrying item.

3. This monitor would operate a shunt trip breaker for that individual circuit.

As for "ground faults", the system above would operate much like our typical systems do now, except the actual fault currents would be minimal if not non-existant. The faulted circuit would be turned off before an actual ground fault could occur. Now, phase to phase shorts would be handled as before.

Systems where continuity of service is required for safety, just omit the shunt trip and substitute a regular breaker.

In reality, we also have to factor in outside influences like lightning or contact with higher utility voltages. For this, it seems that grounding one of the system conductors is the best way to lessen the dangers of these situations.

I admit I don't know much about lightning or accidental contact with higher voltages.
 
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