Purpose of grounding (in California)

[sandsnow]

You know us west coasters do march to our own drummer...

From the CA exam sample questions for Non Residential Lighting Technician:

9.What is the purpose of grounding?
A.To protect equipment
B.To help fasten devices
C.To redirect excess current to the earth
D.To provide an alternative power source

The correct answer according to the Division of Apprentice Standards is "C"

I will now procede to correct all instruction materials I have

 

[TOOL_5150]

You know us west coasters do march to our own drummer...

From the CA exam sample questions for Non Residential Lighting Technician:

9.What is the purpose of grounding?
A.To protect equipment
B.To help fasten devices
C.To redirect excess current to the earth
D.To provide an alternative power source

The correct answer according to the Division of Apprentice Standards is "C"

I will now procede to correct all instruction materials I have

What have you been told in the instruction materials? I would have choose C in the first place.

~Matt

 

[sandsnow]

The two reasons most common:

Limit the voltages due to lightning, line surges or unintentional contact with higher voltage lines.

Stabilize voltage to ground during normal operation.

edit add:

The last place we want current to flow is through the earth

 

[iwire]

What have you been told in the instruction materials? I would have choose C in the first place.

The earth is not an electron sponge, it can not 'absorb' current.

Out of the answers given I would have taken A and got marked wrong.

 

[mxstar211]

I would of marked "C". Grounding is for lighting and voltage surge protection. Bonding is to protect personnel and equipment. . Invest in Holt's Grounding and Bonding book. It will help teach you the differences.

 

[Smart $]

The two reasons most common:

Limit the voltages due to lightning, line surges or unintentional contact with higher voltage lines.

Stabilize voltage to ground during normal operation.

edit add:

The last place we want current to flow is through the earth

If current shouldn't flow to ground, how does grounding achieve the your stated reasons?

Voltage cannot not change if no current can flow.

Would you rather current during or for such events flow somewhere else? ...and if so, where?

 

[Smart $]

The earth is not an electron sponge, it can not 'absorb' current.

Please tell that to every lightning bolt that might hit me

 

[mxstar211]

The earth is not an electron sponge, it can not 'absorb' current.

Out of the answers given I would have taken A and got marked wrong.

I am curious as to why you would choose "A". Please don't take it as an insult, I have read lots of your answers and I know you are very knowledgable, I am just curious about this one. My thoughts are bonding is to protect equipment.

 

[Cavie]

Given the choices, i to woild have chosen A. I do not understand "to redirect current to earth". Sounds you are delibertly trying to redirect the current in the system. Why?

 

[iwire]

Please tell that to every lightning bolt that might hit me

Live up to the name.:roll:

 

[brian john]

.To redirect excess current to the earth

Well this is the answer they want and in a VERY FEW cases this is correct (lightning and possibly high level voltage surges) under day to day operation this seems like the answer of someone that has not a clue about grounding/bonding.


AS Bob noted the Earth is not a great sink for the electricity we utilize to power our homes and businesses.

I would have (MOST LIKELY) chosen "C" based on the fact most inspectors, engineers electricians have major misconceptions regarding grounding. And this is one of the MAJOR misconceptions that lead many of the afore mentioned workers to insist on driving additionally ground rods when there is a power quality issue on the 26th floor data center.

 

[Rockyd]

I can see why California is going banckrupt financially and knowledge wise! Probably had some goof like Robert J. Walsh, City of Hayward Inspector, right the test. My attack on the inspector stems from this thread. Guess there's no reason for me to test in California under the current, wait till they get ran off, then maybe...

 

[sandsnow]

It was just a little joke.

The question was simply stated but still lends itself to the myth of the magical ground rod.

Many people think that driving a rod (grounding something) removes excess current and thus reduces shock potential when the real culprit is bad bonding of the system.

 

[hurk27]

I have to agree with several posters here and say it is "C"

My reason is the wording, it does say grounding and not bonding (which if it did then the others would be correct)

grounding although referenced many places in the NEC, is wrongly termed to mean bonding, this should be wrong!
To me it is the act of Earthing, and we all know Earthing is not for the operation of OCPD's or limiting fault current, or preventing a shock hazard.
The use of the words grounding, grounded, and ground should only be referenced when meaning the term Earthing. for several code cycles now they have tried to clarify this but still there is many references to grounding in the sense of bonding which is not right

the only two uses in the NEC for Earthing is lightning, Voltages from a higher source, both of which can be proved ineffective.:roll:

 

[mxstar211]

I have to agree with several posters here and say it is "C"

My reason is the wording, it does say grounding and not bonding (which if it did then the others would be correct)

grounding although referenced many places in the NEC, is wrongly termed to mean bonding, this should be wrong!
To me it is the act of Earthing, and we all know Earthing is not for the operation of OCPD's or limiting fault current, or preventing a shock hazard.
The use of the words grounding, grounded, and ground should only be referenced when meaning the term Earthing. for several code cycles now they have tried to clarify this but still there is many references to grounding in the sense of bonding which is not right

the only two uses in the NEC for Earthing is lightning, Voltages from a higher source, both of which can be proved ineffective.:roll:

Great answer!!!! I also like how you use the term Earthing. This is definately something the next NEC should clarify.

 

[charlie]

. . . grounding although referenced many places in the NEC, is wrongly termed to mean bonding, this should be wrong! . .

Wayne, a lot of that (all?) has been corrected in the 2009 Indiana Electrical Code (2008 NEC with the Indiana amendments).

 

[scott thompson]

Larry (sandsnow),

That question was also on the 2005 General Electricians' exam! If not verbatim, then very similar in context!

I wanted to make comments to the vague nature of the apparent answer, but with a multiple choice Computer-Based exam, there is no opportunity to do so!

As the answer with the closest relevance was "C", that was the choice I took.

Scott

 

[hurk27]

Wayne, a lot of that (all?) has been corrected in the 2009 Indiana Electrical Code (2008 NEC with the Indiana amendments).

I'm not seeing it, I have read through it but I don't see any changes to article 100, 225, 250 and many more, relating the the use of the term grounding when in context it's meaning bonding?

here is an example:

article 100:

Bonding (Bonded). The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed.

this definition and the next one have the same meaning?

Grounding Conductor, Equipment. The conductor used to connect the non–current-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment or at the source of a separately derived system.

Yet many places in the NEC refer to a grounding conductor in a manner to imply it as a bonding conductor, I know we have been down this road many times, but as what happened in this post with the OP question, as you see even with some of the most well versed NEC people here, there was still a confusion of the meaning of the word "grounding" and we had different answers, this is because of the NEC using the same word but with two different meanings.

I agree with 1049 references to the word "grounding" in the NEC (2002) it would be an undertaking to change this, and I don't know a simple way to make this change but this is still one of the more confusing word definitions in the NEC, and not all times it is clear as to which way it is meant to be taken.

Take the neutral for instance, it's called the grounded conductor (Bonded conductor), yet it is "bonded" to the equipment grounding conductor(Bonding conductor), and the electrode grounding conductor(Earthing conductor), the words in: ()is what I think they should be called.

so just changing a few words could go a long way in making the grounding and bonding issue much easier to understand.

 

[quogueelectric]

You know us west coasters do march to our own drummer...

From the CA exam sample questions for Non Residential Lighting Technician:

9.What is the purpose of grounding?
A.To protect equipment
B.To help fasten devices
C.To redirect excess current to the earth
D.To provide an alternative power source

The correct answer according to the Division of Apprentice Standards is "C"

I will now procede to correct all instruction materials I have

I would most definitely agree but that would not surprise many here.

 

[TOOL_5150]

The earth is not an electron sponge, it can not 'absorb' current.

Out of the answers given I would have taken A and got marked wrong.

Oh, I know. Energy can not be destroyed. However, I guess I am better at answering test questions than I thought.:grin:

FWIW, I was about to go with A, but I would have marked C.

~Matt