Driving a new ground spike

[Bo Deadly]

Notice that earth ground is not involved in ANY of this.

This particular wording is confusing since the EGC is frequently referred to as "earth ground" or "E" or "protective earth" or "PE".

 

[JohnRoberts]

To add to the terminology confusion, NEC (National Electrical Code or just "Code" in the US) refers to the 3 conductors as the "ungrounded" or "line," the "grounded" or "neutral," and the "grounding" or EGC (equipment grounding conductor). One has to read the language of the Code carefully to avoid confusing grounded with grounding.

I wish UL wrote their spec more carefully but that is indeed logical.

But, to the point about fault current, it's important to remember that ALL current flow returns to the source of voltage that is causing the current flow. In the case of fault (or normal load) current, this is the transformer serving your building - and it returns via the neutral conductor from your breaker panel to the transformer. The normal load current will flow to the neutral via the neutral conductor in the branch circuit wiring. But, if an equipment fault occurs, the fault current flows to the breaker panel (and utility neutral0 via the EGC or "safety ground" conductor. Notice that earth ground is not involved in ANY of this. The situation would be identical in an airliner and the wiring is the same. Earth ground is not a universal "sink" for utility power currents. However, earth ground is exactly where lightning currents need to flow to in completing the circuit (for cloud-to-ground strokes - there are cloud-to-cloud strokes that do not involve earth).

+100

JR

PS; @Scott... "equipment grounding conductor" is sufficient.

 

[MisterCMRR]

It's truly unfortunate that the term "ground" or "earth" is commonly used to describe any electrical return path, whether it's actually connected to soil or not. I much prefer to refer to the chassis or power-supply common in equipment as a "return" since it conveys the actual function. But old habits, and names, die hard. But, in order to understand circuits, I think following current flow - and remembering that current will always return to the voltage source that caused it - goes a long way. Thinking only in terms of voltages (even then, we must ask "with respect to what?") can often obscure understanding. I suspect the term "ground" came into use when the only known source of electricity was lightning - think Benjamin Franklin and kites - and has become deeply rooted in our terminology.

 

[JohnRoberts]

I like to joke that ground is a concept, not a node or voltage...

JR

 

[Bo Deadly]

I suspect the term "ground" came into use when the only known source of electricity was lightning - think Benjamin Franklin and kites - and has become deeply rooted in our terminology.

I don't think it's inappropriate to refer to EGC as "ground". It is connect to "the ground" (as in soil) enough to hold 0V references to the same potential which can be important w/ audio devices that don't use Jensen transformers. So it serves a purpose other than as a return for fault currents. Just because currents are not flowing into the ground (as in soil) doesn't render the concept of being "grounded" invalid.

 

[MisterCMRR]

I don't think it's inappropriate to refer to EGC as "ground". It is connect to "the ground" (as in soil) enough to hold 0V references to the same potential which can be important w/ audio devices that don't use Jensen transformers. So it serves a purpose other than as a return for fault currents. Just because currents are not flowing into the ground (as in soil) doesn't render the concept of being "grounded" invalid.

Hold 0V "reference" with respect to what? How would you explain EGC in an airplane other than as a fault current path?

 

[MisterCMRR]

Hold 0V "reference" with respect to what? How would you explain EGC in an airplane other than as a fault current path?

I'm not saying there's anything wrong with the concept of grounding for safety. It's just that the word itself is so vague because of being used to describe circuit connections. The "ground" in an airplane or boat is the hull or frame (nothing to do with earth) and the "ground" in any piece of gear with a 2-wire AC cord is undefined ... it simply floats ... but it's not a hazard (provided it's UL listed) and also useable in audio systems. It confuses a lot of people. And it doesn't take a ground rod at your home to keep neutral within a safe voltage with respect to actual soil because the utility company ties the neutral to earth in many, many places before it gets to you. The only reason you have a ground rod (electrode) at a home is to keep a strike from getting inside the home.

 

[Newmarket]

I like to joke that ground is a concept, not a node or voltage...

JR

I think it's much better than a joke ! Maybe as a result of 'battling' mechanical engineers wrt EMC. As in "I don't care that you've 'Buzzed it thru' - it's still going to fail same as it did last time"

 

[Newmarket]

I don't think it's inappropriate to refer to EGC as "ground". It is connect to "the ground" (as in soil) enough to hold 0V references to the same potential which can be important w/ audio devices that don't use Jensen transformers. So it serves a purpose other than as a return for fault currents. Just because currents are not flowing into the ground (as in soil) doesn't render the concept of being "grounded" invalid.

I say that "soil" or the planet earth doesn't necessarily come into it. But apart from that I think I should say (in a BBC style ) - "Other makes of transformers are available".

 

[Bo Deadly]

Hold 0V "reference" with respect to what?

With respect "to the same potential" as in with respect to all interconnected devices. Devices are bathed in E and H fields which can create significant common mode noise on line and neutral. So by holding everything near ground, even gently through a small resistor, might make a big difference in noise performance. You can't do that without the EGC conductor.

How would you explain EGC in an airplane other than as a fault current path?

For an airplane you do not need ground as a reference because the airplane is not connected to anything else as it is quite literally floating. Except perhaps when mid-air refueling in which case there is no doubt the aviation equivalent of an EGC conductor that must make contact first to discharge the two aircraft and bring them to the same potential.

 

[leadbreath]

Jesus what a drama...lets just remember that countries have differenr systems and regulations. I've lived on 3 continents and never heard of "grounding" its always been "earthing" and the L stands for "Live" ****** it!!!!

 

[moamps]

Go to https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
Read carefully starting at page 17. See especially pages 27 and 29. Earth ground rods are ONLY a measure against lightning. Earth grounds do NOT protect people from being electrocuted when equipment fails (as it often does) in a way to put full AC line voltage on its touchable parts. Safety ground provides a low-impedance (low enough to cause a high fault current to trip a breaker) path back to NEUTRAL, not earth ground. I had a guy who was preaching this gospel of "use your own ground rods instead of neutral" (as page 29) kicked out of a trade show - I reminded the show staff of their legal liability letting this moron promote this deadly practice!

Does that mean this wireing is faulty in your opinion?



https://www.electricaltechnology.or...ical-wiring-installation-in-home-nec-iec.html
(earthing conductor is connected to ground rod )

 

[Bo Deadly]

Does that mean this wireing is faulty in your opinion?

I don't understand. Is there something about that diagram that would stop fault current from getting back to neutral? I see neutral lines running into each breaker. What is it about this that you think might be construed as "faultly"?

 

[Brian Roth]

In the USA, the neutral and grounding bus bars must be tied (bonded) together at the breaker panel.

Bri

 

[moamps]

What is it about this that you think might be construed as "faultly"?

Neutral and earth/ground aren't connected together.

 

[abbey road d enfer]

IINM I don't see Neutral connected to Earth. I think it's called régime TT. Distribution is 2-wire, L & N, no separate protective ground.
My house is wired like that.

 

[Newmarket]

Well there are different 'Earthing' schemes used in different countries / territories. And there are indeed arguments over which is safest. Depending on the probability of various fault conditions on the external supply as well as inside the property. I'd dig out the initials/types but it's late here.
Much depends on the trip device type. If it is dependent on the absolute level of current then it is more easily 'fooled' than if it reacts to a difference in current on L & N. IE if a load of current is going down to the 'Ground Rod' then there will be much less going back via the Neutral and that difference can trigger the device.

 

[Bo Deadly]

Neutral and earth/ground aren't connected together.

So earth is not connected to neutral in an RCBO breaker? That is odd. In that case fault current would go through the earth ground electrode, through soil to neutral at the utility pole. Probably not a good arrangement for a studio.

Update:

Actually it looks like any imbalance (Residual Current Breaker with Overload) will trip it. So as long as the earth ground electrode impedance isn't too high, EGC doesn't need to be connected to neutral for safe operation.

 

[JohnRoberts]

Neutral and earth/ground aren't connected together.

yes they are but only at the mains distribution panel.
==
I have heard of RCD (similar to GFCI) but not RCBO?
==
Soil is not a reliable conductive return path unless you are dealing with lightning level voltages.

JR

 

[Brian Roth]

I found this:

https://www.quora.com/What-is-the-difference-between-RCCB-and-RCD?share=1
I recall seeing Square D (or similar) "breakers" which install in the panel which also incorporated what I recall as GFCI (Ground Fault Current Interruptor) for circuits feeding the kitchen and bathroom or outdoor receptacles. They had a "white" and a "black" (Line and Neutral) connection for both input and output.

In my house, the "safety" is done on individual receptacles in the kitchen (near the sink) and in the bathroom.

Bri