What Is Electrical Grounding?

[dereckbc]

I was already getting the feeling, how did I get sucked into this thread.

Simple you bare false witness against Don and I.

 

[jxofaltrds]

Update: Another true vote!



PS I did not vote.

 

[__dan]

Simple you bare false witness against Don and I.

True witness. Repeatedly in the thread you have been saying grounding is unsafe, unreliable, confusing. I have been saying grounding has a specific and important meaning, and that there are two grounding types, equipment and earth. Both are required extensively.

My request stands unanswered. Cite your specific occurrence, give true witness, where you have seen an earth connection made, the equipment ground omitted, and the system called grounded. The claim has been made that this is happening and a change to prevent this is necessary. I have never seen an earth ground substituted for the equipment ground. The usual violation is using the neutral as an EGC and the omission of the GEC where required in 250.30 ( A ) 3 and 4.

I am busy responding to the same type mess from a different source.

 

[mivey]

Answer these two questions.

1. Let's say you set a 120 volt battery on the ground with no wiring of any kind and you touch either polarity. What happens to you?.


2. A bird lands and perches on a 1 MV overhead line. What happens to the bird?

The only right answer is NOTHING.

There is no complete circuit to conduct current.

You would be wrong. You forgot the effect of little things like electric and magnetic fields. Care to take a seat on a 1 MV line? You might be surprised. To say NOTHING happens is a bit absolute. You would find that the fields will creates fields and currents in your body. The environment outside your body is also affected. I suspect you might find the whole experience unsettling. I suspect the birds would also but I have no 1 MV lines nearby to check.

Even at 120 volts we have a field though the strength is probably pretty weak for the configuration and you probably would not notice any effects. They may produce reactions in animals but I'm not sure at what field strength. I'm sure there are studies and I may have read it before but I can't remember any specific figures.

 

[dereckbc]

True witness. Repeatedly in the thread you have been saying grounding is unsafe, unreliable, confusing. I have been saying grounding has a specific and important meaning, and that there are two grounding types, equipment and earth. Both are required extensively..

Like I said before you are are confusing a Grounded System. and Grounded. They are two different things and until you understand the difference, there is no point in discussing it any further.

 

[dereckbc]

Equipment grounding is a strictly specified and required system that will trip a breaker using code required materials and methods. Under the existing code, the EGC is eventually bonded back to the GEC and the earth.

That is only half true and a breaker will only operate from over current in a Grounded System like a Wye or Single Phase System. In an ungrounded system like Delta, a phase fault to equipment will not operate a OCPD by design. You are still obligated to ground the equipment, but that does not make it a grounded system.

 

[jxofaltrds]

I forgot about this bird!

http://www.bing.com/videos/search?q...&mid=9B1F7D8FC053D306C31E9B1F7D8FC053D306C31E

 

[don_resqcapt19]

... Residential GFI's have a useful life less than five years. They go bad frequently and fail to trip on the red button but the power is still on (they do not self test or alarm for protective function failure). ...

UL 943 was changed in 2006 to require "self testing" of the GFCI electronics, however that standard does not require that a failed self test result in the device tripping.

The first new requirement is referred to as ?End of Life.? In the event that a GFCI?s electronic circuitry can no longer provide safe, protected power, UL now requires that the product render itself incapable of delivering power and/or provide a visual and/ or audible indicator to alert the user of this ?End of Life? condition.

...Ungrounding, removing the earth reference from the frame, can never be accomplished in practice. There will always be haphazard and unintentional earth contact with the exposed metal of the load or its attached systems. You are describing something you can only build in a lab that works only during the test period. ....

While not completely practical on a large scale is it done in most all operating rooms and emergency rooms in US hospitals.

...250.4 ( A ) 1 through 5 is pretty clear. This thread is claiming 250.4 is improperly worded.

I am only saying the term EGC is not correct.

The problem is not with the naming convention, it would be with the lazy clueless fakers ignoring what the code says. Changing the name will not make the lazy suddenly get up and go, the clueless suddenly become competent.

We are continuing to "dumb" down the code so users can correctly understand and comply with it to install safe electrical systems. The mis-application of "grounding" is a big issue, and it remains my opinion that a giant step to prevent the mis-application could be made by using a more correct term for the Equipment Grounding Conductor". My preference would be the term "Equipment Bonding Conductor", but others such as "fault clearing conductor" would be acceptable to me.

I think we can just agree to disagree on the re-naming of the EGC as I am firmly convinced that such re-naming would improve the understanding and application of the code.

 

[mivey]

I forgot about this bird!

That would be a big ouch without the suit.

 

[mivey]

You would be wrong. You forgot the effect of little things like electric and magnetic fields. Care to take a seat on a 1 MV line? You might be surprised. To say NOTHING happens is a bit absolute. You would find that the fields will creates fields and currents in your body. The environment outside your body is also affected. I suspect you might find the whole experience unsettling. I suspect the birds would also but I have no 1 MV lines nearby to check.

Just for a relative estimate for a 1 MV line I calculate on the order of 98,000 mG, 5700 kV/m, and 84 mA of induced body current a few tenths of inches above the conductor. At one foot I get 5600 mG, 321 kV/m, and 5 mA of induced body current.

Animals are more tender about fields than we are so I doubt a bird is going to perch on a 1 MV line but I have no empirical data.

 

[resistance]

Interesting comments! This topic has confused many and many are still confused in my opinion!

 

[mivey]

I suspect it is pretty much unanimous except for some trues made in jest.

 

[UK Des]

Interesting comments! This topic has confused many and many are still confused in my opinion!

I will firstly say hello and with this first post I will apologise for making no effective contribution to this debate

Living in Wales (a country of the UK ) I will be reading and hoping to understand your own systems and regulations etc (over time),so please excuse my ignorance at this moment

However, I must say you have very different terminology to us Brits :huh: Also your interpretation of what is defined as "Earthing" or "Grounding" as it seems to be called, and what is defined as
bonding,it is very very different to my own definitions
At the moment your examples and definitions are very "alien" to me indeed
I will not be deterred however,I do hope to get to understand enough of your systems (and the regs involved) to make a contribution in the future,but for the time being, I will continue to read with interest this and other threads that seem to have opened a Pandora's box of new tricks for me to digest

 

[jxofaltrds]

I will firstly say hello and with this first post I will apologise for making no effective contribution to this debate

Living in Wales (a country of the UK ) I will be reading and hoping to understand your own systems and regulations etc (over time),so please excuse my ignorance at this moment

However, I must say you have very different terminology to us Brits :huh: Also your interpretation of what is defined as "Earthing" or "Grounding" as it seems to be called, and what is defined as
bonding,it is very very different to my own definitions
At the moment your examples and definitions are very "alien" to me indeed
I will not be deterred however,I do hope to get to understand enough of your systems (and the regs involved) to make a contribution in the future,but for the time being, I will continue to read with interest this and other threads that seem to have opened a Pandora's box of new tricks for me to digest

Welcome.

We don't understand the terms so jump in. Please never take anything said here as an attack or personal. We just debate very seriously at times.

 

[dereckbc]

I will firstly say hello and with this first post I will apologise for making no effective contribution to this debate

Living in Wales (a country of the UK ) I will be reading and hoping to understand your own systems and regulations etc (over time),so please excuse my ignorance at this moment

However, I must say you have very different terminology to us Brits :huh: Also your interpretation of what is defined as "Earthing" or "Grounding" as it seems to be called, and what is defined as
bonding,it is very very different to my own definitions
At the moment your examples and definitions are very "alien" to me indeed
I will not be deterred however,I do hope to get to understand enough of your systems (and the regs involved) to make a contribution in the future,but for the time being, I will continue to read with interest this and other threads that seem to have opened a Pandora's box of new tricks for me to digest

Welcome.

Please do not apologize as their is no need. IMHO you brits got it right. What we yanks did was make it difficult so as to confuse the Russians and Chi-Coms.

As for your learning curve good luck. I suggest you start by translating terms. For example what you brits call Protective Earth (PE) we yanks call it Equipment Ground Conductor (EGC). Now to confuse the Russians and Chi-Coms we now call it Equipment Bonding Jumper.