Grounding VS Bonding

[RB1]

I disagree that the equipment grounding conductor is inappropriately named. From the very beginning of the Code there have been two types of grounding; equipment grounding, and system grounding. The equipment grounding conductor connects equipment to the earth in both grounded and ungrounded systems. By doing so, the potential between the equipment and earth is limited. Equipment grounding is something that takes place throughout the entire premises wiring system, while bonding on the other hand, is simply a POINT of connection, either mechanically, or through the use of a short length of conductor in the form of a wire or busbar. Anyway, thats how I understood it when I first read the 1981 NEC. If someone doesn't understand the difference between system grounding and equipment grounding, changing the name of one term is not going to help them.

 

[suemarkp]

The equipment grounding conductor connects equipment to the earth in both grounded and ungrounded systems. By doing so, the potential between the equipment and earth is limited.

How does it connect to earth on an ungrounded system (at least in non-fault mode)? Really, isn't the primary idea of equipment bonding to provide a high current fault path between metal cabinets/enclosures and the power source? If so, that doesn't have anything to do with the earth. It only needs a common reference point as the safety return path. Most people call this ground, as it ends up connecting to earth too in most instances, or the electronics type is using that term to shunt all the junk signals to. But for many usages of "ground", connection to the earth is not required.

There are some higher voltage issues that are addressed via the equipment grounding conductor (provides a means to bleed off static electricity in rotors or blades), where connecting it to earth is helpful to dissipate it.

But I disagree that the EGC safely limits the potential between earth and the equipment. The earth resistance is too high to pull voltages down to a safe level. If you have a ground electrode directly under the equipment and keep your feet on it, then the equipment and earth are at the same potential. But get your feet 3 or more feet away from the ground electrode, or the ground electrode 3 or more feet away from the equipment, and you could easily have 100+ volts between earth and grounded equipment. Go stick the ungrounded conductor from a 120V source onto a lone ground rod and you'll notice the circuit breaker won't blow. Touch that rod with your feet a few feet away from it and you'll get a nice shock. Connecting a chassis to earth is really for dropping higher voltages down or tripping overcurrent devices at 600V and above.

 

[ActionDave]

The equipment grounding conductor connects equipment to the earth in both grounded and ungrounded systems. By doing so, the potential between the equipment and earth is limited.

Not sure what you mean by this.

Equipment grounding is something that takes place throughout the entire premises wiring system, while bonding on the other hand, is simply a POINT of connection, either mechanically, or through the use of a short length of conductor in the form of a wire or busbar. Anyway, thats how I understood it when I first read the 1981 NEC. If someone doesn't understand the difference between system grounding and equipment grounding, changing the name of one term is not going to help them.

Here I agree completely. Bond and the service or SDS and nowhere else.

I understand the desire to use the term "bonding" as a way to clarify and distinguish equipment grounding from grounded but it does not; it just adds the need to distinguish between "bond", "bonded", and "bonding".

Grounded vs. Equipment Grounding is well understood by anybody that knows enough to care.

 

[iwire]

If someone doesn't understand the difference between system grounding and equipment grounding, changing the name of one term is not going to help them.

I think changing the name could help, it certainly will not hurt.

 

[Volta]

Yeah, I wold love to reserve the term "grounding" for connecting electrical systems to the earth, and variations of "bonding" for making the various non-current carrying mettalic components electrically continuous.

Maybe using "earthing" for GEC could help.

Heck, if we could just reduce the number of times people say "the ground wire" we'd be in better shape.

 

[iwire]

Heck, if we could just reduce the number of times people say "the ground wire" we'd be in better shape.

:thumbsup:

 

[Rick Christopherson]

Equipment grounding is something that takes place throughout the entire premises wiring system, while bonding on the other hand, is simply a POINT of connection, either mechanically, or through the use of a short length of conductor in the form of a wire or busbar.

I agree and have have been saying this for years here. When people view the grounding system differently or as two parts upstream and downstream from the bonding point, they also tend to overlook all of the different functions of the grounding system.

When you begin to visualize it as a complete grounding system which has a bonding location, instead of two separate systems, then it makes it easier to realize the many functions it provides. It even limits what people believe is the sole perpose of the bonding point, which also has more than one function.

 

[GoldDigger]

I agree and have have been saying this for years here. When people view the grounding system differently or as two parts upstream and downstream from the bonding point, they also tend to overlook all of the different functions of the grounding system.

When you begin to visualize it as a complete grounding system which has a bonding location, instead of two separate systems, then it makes it easier to realize the many functions it provides. It even limits what people believe is the sole perpose of the bonding point, which also has more than one function.

One problem that I have with that approach is that it leaves a hole in the terminology for something like a swimming pool equipotential grid, in which all of the exposed conductive surfaces are bonded to one another but not necessarily grounded. Your suggestion, IMO, does not make it any easier to understand the function of that bonding network.

 

[dereckbc]

I like to keep the Chi-Coms and Russians confused.

 

[Rick Christopherson]

One problem that I have with that approach is that it leaves a hole in the terminology for something like a swimming pool equipotential grid, in which all of the exposed conductive surfaces are bonded to one another but not necessarily grounded. Your suggestion, IMO, does not make it any easier to understand the function of that bonding network.

No, it is quite the opposite. As a matter of fact, I think this may be a confusing usage of the typical term "bonding", at least in the way it gets thought of most often. A "bond" simply means connected together. It does not mean the function is something specific, such as ground-to-neutral bond.

The equipotential grid is there to establish that no voltage gradients exist around the pool. That's why even non-electrical equipment is connected to the grid (If I understand the requirements, but I haven't read that section in a long time).

What a lot of people don't realize is that the Earth has voltage gradients all over the place. Some are man-man, but many are also natural. The reason why many people overlook the natural gradients is because we always refer to the Earth as "zero volts". But zero volts to what reference? The "local" Earth is the reference itself, but that doesn't mean it will show zero volts between two different points.

 

[GoldDigger]

No, it is quite the opposite. As a matter of fact, I think this may be a confusing usage of the typical term "bonding", at least in the way it gets thought of most often. A "bond" simply means connected together. It does not mean the function is something specific, such as ground-to-neutral bond.

The equipotential grid is there to establish that no voltage gradients exist around the pool. That's why even non-electrical equipment is connected to the grid (If I understand the requirements, but I haven't read that section in a long time).

What a lot of people don't realize is that the Earth has voltage gradients all over the place. Some are man-man, but many are also natural. The reason why many people overlook the natural gradients is because we always refer to the Earth as "zero volts". But zero volts to what reference? The "local" Earth is the reference itself, but that doesn't mean it will show zero volts between two different points.

Sorry, my reply was meant to be to Volta's post. (I was on a smart phone and got lost....)

There is a "true" ground/earth potential for practical purposes which can be tapped by going deep enough that you do not intercept any man-made currents. But if you go far enough down there are also circulating currents in the molten core which lead to the earth's magnetic field. So don't go too deep.

 

[electrofelon]

I disagree that the equipment grounding conductor is inappropriately named. From the very beginning of the Code there have been two types of grounding; equipment grounding, and system grounding. The equipment grounding conductor connects equipment to the earth in both grounded and ungrounded systems. By doing so, the potential between the equipment and earth is limited. Equipment grounding is something that takes place throughout the entire premises wiring system, while bonding on the other hand, is simply a POINT of connection, either mechanically, or through the use of a short length of conductor in the form of a wire or busbar. Anyway, thats how I understood it when I first read the 1981 NEC. If someone doesn't understand the difference between system grounding and equipment grounding, changing the name of one term is not going to help them.

Then why is the misapplication and misunderstanding of this topic continue to be a chronic serious problem in the electrical industry? Two reasons (IMO): the fact that grounding is a homophone, that is same word with multiple different meanings, and that the NEC lumps fault clearing systems and earthing systems in the same article. This is just as ridiculous as lumping together, say, article 650( pipe organs), and 350 (LFMC) in the same article. Yes the EGC does double duty as connecting equipment to earth and providing a low impedance path back to the source, but these roles are completely different and the former is very minor in importance compared to the latter. Sorry I get real worked up whenever this topic comes up: all the crap that has been getting into the NEC lately but they cant straighten this out....

 

[ActionDave]

Then why is the misapplication and misunderstanding of this topic continue to be a chronic serious problem in the electrical industry? Two reasons (IMO): the fact that grounding is a homophone, that is same word with multiple different meanings, and that the NEC lumps fault clearing systems and earthing systems in the same article. This is just as ridiculous as lumping together, say, article 650( pipe organs), and 350 (LFMC) in the same article. Yes the EGC does double duty as connecting equipment to earth and providing a low impedance path back to the source, but these roles are completely different and the former is very minor in importance compared to the latter. Sorry I get real worked up whenever this topic comes up: all the crap that has been getting into the NEC lately but they cant straighten this out....

I think your idea of breaking up 250 has some merit. I know one thing for sure- tossing in the terms BONDED and BONDING don't clear things up at all. I grabbed this quote from another thread to illustrate...(emphasis added it mine)

I think OP possibly needs a better understanding between the differences between a "grounded" conductor and an "equipment grounding" conductor. He needs to forget about the fact he has a PLC and forget that he has a solenoid for a moment and understand the general rules of power source, services/and or feeders, separately derived system, then grounding and bonding, and the fact that he has a load that happens to use a "grounded" conductor as one of its supply conductors.

Richard - you have a load that uses a "grounded" conductor. This conductor, though it is tied to the "grounding conductor" back at/near the source is not permitted to bond to non current carrying metal objects beyond the bonding jumper at/near the source. To bond beyond that point allows normal operating current to flow through unintended paths of metallic components of equipment, which can cause other problems with stray currents and voltages.In your application you need a separate neutral and equipment grounding conductor to your solenoid. The neutral will be a conductor with insulation on it, the equipment grounding conductor may be a "conductor" or it could be metallic raceways or cable sheaths if they meet requirements in art 250 part VI.

Grounded and grounding has been hashed out long enough that equipment grounding is well understood.

Bond, bonding, bonded, where to bond, why is there only one place to bond but everything has to be bonded?? Why not add some new terminology to keep the next generation guessing....We all had to sort through it why should they be excused?

 

[don_resqcapt19]

...Grounded and grounding has been hashed out long enough that equipment grounding is well understood.

...

I don't agree...far too many still think that you can provide equipment "grounding" by a connection to a grounding electrode. This problem will continue as long as we continue to use the term equipment grounding conductor.

 

[ActionDave]

I don't agree...far too many still think that you can provide equipment "grounding" by a connection to a grounding electrode. This problem will continue as long as we continue to use the term equipment grounding conductor.

If I say, "Equipment Grounding Conductor" you know exactly what I am talking about.

Come on now, work with me here and we can make this world a better place.

 

[don_resqcapt19]

If I say, "Equipment Grounding Conductor" you know exactly what I am talking about.

Come on now, work with me here and we can make this world a better place.

I do, but many don't. The term would be more correct if it was "equipment bonding conductor" as its purpose is to bond the non current carrying parts to the grounded conductor (via the main bonding jumper) to provide a fault clearing path.

 

[ActionDave]

.....The term would be more correct if it was "equipment bonding conductor" as its purpose is to bond the non current carrying parts to the grounded conductor (via the main bonding jumper) to provide a fault clearing path.

I get that, but when you start using that more correct language all you do is move the confusion about grounding over to bonding. Nothing gets better.

Teaching everybody the how to use two terms correctly sure seems much easier than four. I'm sure there is somebody here that can do the math on that to bolster my position.

 

[don_resqcapt19]

I get that, but when you start using that more correct language all you do is move the confusion about grounding over to bonding. Nothing gets better.

Teaching everybody the how to use two terms correctly sure seems much easier than four. I'm sure there is somebody here that can do the math on that to bolster my position.

The terms need to be technically correct and they are not now. I don't see how that adds to the confusion. The confusion comes from the fact that the current term implies that all you need to do for equipment grounding is to connect the equipment to the earth. Far too many still think that a connection to earth will make the equipment safe from electrical shock hazards and that is not the case. Even the EGCs do not eliminate the shock hazard, but they do act, in a correctly installed system, to limit the duration of that shock hazard.

I have been told that when the Canadian Electrical Code went to the term equipment bonding conductor, much of the confusion as to what the term means went away.

As a side note, proposals for the 2005 code by myself and a couple of others to replace the the term equipment grounding conductor with equipment bonding conductor were accepted by a majority of the members of CMP 5, but were reported as rejected because they were not accepted by a 2/3s majority as required by the NFPA rules to make a code change. They have been taking steps to resolve this confusion in the cycles since then, but still have stopped short of doing what they need to do.

 

[jwelectric]

The way I have been taught be it right or wrong the EGC is required by 250.4(A)(2) to connect normally non?current-carrying conductive materials enclosing electrical conductors or equipment to earth and the purpose for this is to limit the voltage to ground on these materials.

Bonding on the other hand is the process of connecting normally non?current-carrying conductive materials enclosing electrical conductors or equipment together and to the neutral at the service disconnect as required by 250.4(A)(3) in a manner that establishes an effective ground-fault current path

In cases where the raceway is the EGC the process of bonding together the raceway is accomplished with the raceway but this bonding path is allowed by 250.118 to be the EGC but if the EGC is installed in nonmetallic raceways and enclosures is it bonding anything as required in 250.4(A)(3)? If not then why would we want to call it a bonding anything?

 

[ActionDave]

The terms need to be technically correct and they are not now. I don't see how that adds to the confusion. The confusion comes from the fact that the current term implies that all you need to do for equipment grounding is to connect the equipment to the earth. Far too many still think that a connection to earth will make the equipment safe from electrical shock hazards and that is not the case. Even the EGCs do not eliminate the shock hazard, but they do act, in a correctly installed system, to limit the duration of that shock hazard......

The quote I pulled from another thread is a perfect example.