Please explain

[stevenmallet]

Please explain the difference between bonding and grounding. This forum wants 100 words. I don't how else to ask this.

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[480sparky]

Bonding brings the various exposed metal parts of an installation to the same potential so there's not a voltage gradient between them that could produce a shock.

Grounding provides a path for faults to follow to provide sufficient current to flow and open the OCD.

 

[Little Bill]

I'm just going to try and explain a simple service to a building.
Grounding is a deliberate connection to earth/dirt. Usually done with the grounded conductor for service. The grounded conductor, sometimes called a neutral is connected to a neutral bar in the panel. Some type of grounding electrode is placed in the earth, which is usually ground rods. A conductor is ran from that to the neutral bar at the panel. This conductor is called a GEC (grounding electrode conductor)Now the system is grounded. This is the only place the system should be grounded.

Now to the bonding. Since there is only one place that the system is grounded everything else is bonded. That means to connect/tie all metal paths together. To explain that a bit may help you distinguish between the two. In the panel, you have the neutral bar. The neutral bar has to have continuity to a grounding bar. (notice I said groundING). All the circuits have an equipment grounding conductor called an EGC. These land on the grounding bar. The neutral bar and ground bar have to have something to connect or bond them together. This is called a [main] bonding jumper. This is so a fault somewhere downstream will have a path back to the panel to trip a breaker. In the main panel is the ONLY place the ground(neutral) bar and the grounding(EGC) should be connected. Along the circuit you may have metal boxes, cabinets, etc., these have to be bonded/connected to the EGC. The EGC is the path back to the panel for a fault/short.

This is a short version and just gives basics so I didn't go into a lot of detail. But in short:
ground = earth
bond = connecting all metal paths together

 

[LarryFine]

Just to add, we tend to use the word grounding when referring to EGCs, where they function by bonding conductive surfaces that could possibly become energized to a grounded service conductor in order to operate short-circuit protective devices.

 

[jusme123]

In addition to the above posts, also see the definition of each in the NEC, ART 100, don’t want you to lose stupid points on a license test

 

[oldsparky52]

Grounding provides a path for faults to follow to provide sufficient current to flow and open the OCD.

Grounding provides means to open OCD? Did you really mean to write it that way?

 

[Besoeker3]

I'm just going to try and explain a simple service to a building.
Grounding is a deliberate connection to earth/dirt. Usually done with the grounded conductor for service. The grounded conductor, sometimes called a neutral is connected to a neutral bar in the panel.

For me, neutral and grounding (earthing) are two different things. A star or wye is three phase and neutral whether or not the neutral is grounded.
I have noticed that, on this forum, there is a tendency to use the two terms interchangeably.

 

[oldsparky52]

Grounding provides means to open OCD? Did you really mean to write it that way?

I believe re-reading Larry's post #4 explains this.

 

[480sparky]

Grounding provides means to open OCD? Did you really mean to write it that way?

How else do faults get cleared?

 

[oldsparky52]

How else do faults get cleared?

Bonding with what we call a ground wire? I always considered grounding to be "earthing" one of the conductors.

I think Larry cleared it up, it's a matter of semantics.

 

[ActionDave]

The way I sort it out in my own head is grounded is connected to the earth. Anything to do with clearing a fault is equipment grounding.

 

[480sparky]

Bonding with what we call a ground wire? I always considered grounding to be "earthing" one of the conductors.

I think Larry cleared it up, it's a matter of semantics.

Faults are cleared with grounding conductors, connected to ground terminals. Not bonding conductors and bond terminals.

Yeah, the terminology is confusing given that the function of both overlap in so many areas. I'd prefer choosing just one term and running with it.

 

[winnie]

Yes, it is semantics, and with such a history I don't think anyone could actually un-muddle them. The best we can do is understand the physics.

My opinion on the semantics:

1) we connect together all conductors that are not _intended_ to carry current in normal operation. This is _bonding_. We bond conduit, we bond the metal chassis of equipment, etc.

2) We usually connect a single point of an electrical system to the bonded metal. This connection is generally made at the service, and does a bunch of things. a) it facilitates operation of OCPD when there is a fault between a circuit conductor and bonded metal. b) it stabilizes the voltage between circuit conductors and the surrounding bonded metal. This connection is called 'grounding' as in a 'grounded neutral system', however this connection is made with the 'main bonding jumper'

3) We are required to connected bonded metal to an earth electrode. This is also called 'grounding' and has nothing to do with operation of OCPD.

-Jon

 

[bwat]

If I'm not mistaken, Mike Holt has been trying to get the term changed everywhere in the NEC from Equipment Grounding Conductor, to Equipment Bonding Conductor unsuccessfully for years now. I think I saw this on one of his code change videos not too long ago.

The existence of GEC to take one of your circuit conductors to be referenced to ground (earth) has no impact on an EGC's ability to provide a fault current path. So EGCs are really about bonding to get fault current back to the source to clear the fault, and actually has no bearing on earth/ground.

 

[Little Bill]

For me, neutral and grounding (earthing) are two different things. A star or wye is three phase and neutral whether or not the neutral is grounded.
I have noticed that, on this forum, there is a tendency to use the two terms interchangeably.

Yes, the two get interchanged here. Not technically correct but the OP sounds like a student, and to keep it simple, I just used neutral for the grounded conductor.

 

[Besoeker3]

Yes, the two get interchanged here. Not technically correct but the OP sounds like a student, and to keep it simple, I just used neutral for the grounded conductor.

Fairy 'nuff. You know my background is industrial power electronics is my field.Some of it was high current (like 40kA) rectifiers. These were hexaphase. The transformers windings were at 60 degree intervals like a wheel with six spokes. The star point was the negative, (not grounded) so the current went through just one SCR at a time for a 60deg period. In the configuration for the front end of a VFD rectifier the current does through two semiconductors, each for a 120deg period.

 

[ActionDave]

If I'm not mistaken, Mike Holt has been trying to get the term changed everywhere in the NEC from Equipment Grounding Conductor, to Equipment Bonding Conductor unsuccessfully for years now. I think I saw this on one of his code change videos not too long ago.

The existence of GEC to take one of your circuit conductors to be referenced to ground (earth) has no impact on an EGC's ability to provide a fault current path. So EGCs are really about bonding to get fault current back to the source to clear the fault, and actually has no bearing on earth/ground.

No. He talks about bonding but when it comes to fault clearing he uses Equipment Grounding Conductor. I noticed this in his last round of live streams because this has been my chosen term for twenty five years and I felt quite validated.

Forget about trying to change everything to equipment bonding conductor. If say equipment grounding conductor to anyone who knows enough to care he will know exactly what I'm talking about.

 

[don_resqcapt19]

Bonding connects things together and provides the fault clearing path. Grounding connects things to earth.

 

[bwat]

No. He talks about bonding but when it comes to fault clearing he uses Equipment Grounding Conductor. I noticed this in his last round of live streams because this has been my chosen term for twenty five years and I felt quite validated.

Forget about trying to change everything to equipment bonding conductor. If say equipment grounding conductor to anyone who knows enough to care he will know exactly what I'm talking about.

Oh great, now I have to try to find the video where he stated this ... might be a while.

Yes, if you say EGC, we know what you mean, but it's somewhat of a misnomer.

In the meantime until I find that video reference, check out this article from MH:

Grounding versus Bonding Part 8 of 12

www.mikeholt.com

"Thus, the EGC is really not a grounding conductor at all, but a bonding conductor. "

"If you are joining metallic parts, you are bonding. If you are connecting to earth, you are grounding. "

"Don't let the "grounding" part of the EGC confuse you. It's really the equipment bonding conductor. Don't think in terms of "grounding" equipment-that is, connecting it to the earth [100]. Think in terms of connecting it to the system grounded conductor or the grounding electrode conductor (or both). Remember, the low-impedance fault-current path you create is necessary for overcurrent protection devices to operate. Earth is not a low-impedance fault-current path. "

 

[ActionDave]

Oh great, now I have to try to find the video where he stated this ... might be a while.

Yes, if you say EGC, we know what you mean, but it's somewhat of a misnomer.

In the meantime until I find that video reference, check out this article from MH:

Grounding versus Bonding Part 8 of 12

www.mikeholt.com

"Thus, the EGC is really not a grounding conductor at all, but a bonding conductor. "

"If you are joining metallic parts, you are bonding. If you are connecting to earth, you are grounding. "

"Don't let the "grounding" part of the EGC confuse you. It's really the equipment bonding conductor. Don't think in terms of "grounding" equipment-that is, connecting it to the earth [100]. Think in terms of connecting it to the system grounded conductor or the grounding electrode conductor (or both). Remember, the low-impedance fault-current path you create is necessary for overcurrent protection devices to operate. Earth is not a low-impedance fault-current path. "

I'm not saying he doesn't talk about grounding vs bonding. He still does that, but he doesn't talk about trying to change the code to equipment bonding conductor he says equipment grounding conductor.

In Europe they call it protective earth which is even more of a misnomer. That doesn't bother me either. I rather like the term. I'm sticking with egc because it's established here in the USA