Grounding VS Bonding

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
jwelectric said:
Ever take a voltage reading? That voltage is in reference to what? EARTH



Because it connects all non-current carrying metal that encloses electrical wires and equipment to earth.
Bonding is something like ensuring electrical continuity around expansion joints in metal conduit, the metal boxes used in non-metallic cables, the jumper installed from a metal box to the metal yoke of devices where metal raceways are used.
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And it also provides a low impedance path back to the source. If you are so intent on calling it what it does, shouldnt you be wanting to call it the "equipment grounding and bonding conductor"?

Bonding rules are a lot more lax than equipment grounding so to change the name of equipment grounding to equipment bonding is going to change the rules of the earth connection and the potential of earth and a metal non-current carrying that is elevated above earth. Read 250.4(A)(1) and (2) for more information on the subject. When you read this for a few minutes forget about bonding and let nothing but earth be on your mind. Once this has sunk in real good then proceed with the bonding of your choice.
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How do you conclude that bonding rules are more lax than equipment grounding? Actually I would say that this would be a difficult debate to have because 250 is such a mess and splitting it up into two articles, fault clearing and bonding, is more important IMO than changing EGC to EBC. Tell me this: Article 250.24, are they talking about system grounding, equipment grounding, or fault clearing? I say after reading 250.4(A)(1) they must be talking about system grounding. Glad we got that straightened out. Everyone agree? 250.24 is about system grounding only. The whole part VI of article 250, are they talking about system grounding, equipment grounding, or fault clearing paths? Again reading 250.4(A)(1) I conclude they are only talking about equipment grounding (earthing). Everyone agree there?
 
jwelectric

jwelectric

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Location
North Carolina
electrofelon said:
Tell me this: Article 250.24, are they talking about system grounding, equipment grounding, or fault clearing?
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I think this is found in Part II System Grounding


electrofelon said:
I say after reading 250.4(A)(1) they must be talking about system grounding. Glad we got that straightened out. Everyone agree? 250.24 is about system grounding only.
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Yes I agree

electrofelon said:
The whole part VI of article 250, are they talking about system grounding, equipment grounding, or fault clearing paths?
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I think the title of Part VI is as follows Equipment Grounding and Equipment Grounding Conductors

electrofelon said:
Again reading 250.4(A)(1) I conclude they are only talking about equipment grounding (earthing). Everyone agree there?
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Yep we agree once again
 
electrofelon

electrofelon

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Location
Cherry Valley NY, Seattle, WA
jwelectric said:
I think this is found in Part II System Grounding


Yes I agree

I think the title of Part VI is as follows Equipment Grounding and Equipment Grounding Conductors

Yep we agree once again
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Ok.... but I was being facetious. Thats why 250 is a total mess. If 250.24 is about system grounding, why are they talking about main bonding jumpers? I guess the party wasnt complete with out a little equipment earthing, so they threw in 250.24(E) too.

As for part VI, do you really think they are only talking about equipment earthing? That whole part is just concerned with connecting equipment to earth? If so what is with the common phrase "...likely to become energized", "...the combined length of flexible.........in the ground fault path does not exceed 6 feet", "type MC cable that provides and effective ground fault path.....". then there is the full sized EGC conductor requirement for parallel runs which is due to ground fault issues, then all the stuff about grounding boxes, device yokes etc (that is getting into part VII but the point is still valid). My point is you often cannot tell if the NEC is talking about equipment earthing, fault path, or system earthing, and they are not consistent with their terms. They generally use grounding and bonding interchangeably. I just realized that is the title of the OP, how fortuitous!

The way I think about it is connecting/bonding for fault clearing takes a more solid connection than the connection for what they are trying to achieve by connecting equipment to earth. If you have a document that codifies how to connect equipment together to make an effective fault path, then they will also be connected adequately to achieve the equipment earthing goals. Things would be a lot clearer if they split 250 up (I know I keep trying to sell this idea). 251 would be system and equipment earthing and 252 would be bonding/fault clearing. The part of 251 that is equipment earthing would be pretty simple with scope, definitions, clarification that a conductor can serve both bonding and earthing purposes, and say something like "the requirements in 252 for the establishment of an effective ground fault path meet the requirements of this section". I suppose 250 could stay one article but they would have to get consistent with their terms, but I still say it just as illogical as pipe organs and LFMC together....
 
ActionDave

ActionDave

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See what I mean. Everybody that knows enough to care knows what equipment grounding conductor means. Let's build on that common vocabulary and move forward.

If you know what an equipment ground is for then it doesn't matter what you call it. Why call it something other than what so many of us already do?
 
Sahib

Sahib

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Location
India
dereckbc said:
The whole point is earth is not required
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Gone astray with your diagrams: if there is any direct lightning strike to your system, extensive damage would occur to your system, unless there is grounding as required by the Code.
 
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ggunn

PE (Electrical), NABCEP certified
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Consulting Electrical Engineer - Photovoltaic Systems
Sahib said:
Gone astray with your diagrams: if there is any direct lightning strike to your system, extensive damage would occur to your system, unless there is grounding as required by the Code.
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Ah, well, here we go... :D
 
dereckbc

dereckbc

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Sahib said:
Please tell what it is.
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Earth reference has noting to do with clearing a low voltage fault under 600 volts and is useless/dangerous. Only a PLANNED properly sized EBC (aka EGC) can do that. You have to get up into 4 and 5 digit voltages before earth can become an effective conductor of electricity.

Do not believe me? Ask any POCO engineers,scientist, and NESC for their professional opinion.
 
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Sahib

Sahib

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Location
India
dereckbc said:
Earth reference has noting to do with clearing a low voltage fault under 600 volts and is useless/dangerous. Only a PLANNED properly sized EBC (aka EGC) can do that. You have to get up into 4 and 5 digit voltages before earth can become an effective conductor of electricity.

Do not believe me? Ask any POCO engineers,scientist, and NESC for their professional opinion.
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Your point is correct and too clear already to miss. It is also too clear that if a lightning current seeking earth happens to enter your supposedly 'safe' system described by your third diagram mentioned in your post #57, it is liable to cause further extensive damages to the equipment in your system unless grounded as required by the Code.
 
dereckbc

dereckbc

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Sahib said:
Your point is correct and too clear already to miss. It is also too clear that if a lightning current seeking earth happens to enter your supposedly 'safe' system described by your third diagram mentioned in your post #57, it is liable to cause further extensive damages to the equipment in your system unless grounded as required by the Code.
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What can I say other than you just don't get it. The thread is about changing the name of the EGC to EBC. Earth has noting to do with the operation of a OCPD. NEC forbids earth to used as a conductor.
 
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GoldDigger

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dereckbc said:
NEC forbids earth to used as a conductor.
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NEC forbids earth to be used as a current-carrying conductor in LV wiring, and physics prevents it from being used as a fault-clearing conductor. However, it is still allowed to carry fault current. You cannot prevent that, you can just provide more attractive alternate paths to carry more of the current at a lower voltage drop. (For example, look at a feeder to a separate building, where you have both an EGC/EBC and a local ground electrode. The ground electrode and earth will carry some fault current in the event of a line-to-bonded-surface fault. It will just (hopefully) be very small.
 
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