Ground fault over current protection misinformation--is this what I have found?

[ericsarratt]

I have been reading a lot about grounding and bonding and watching Mike Holt's videos on the subject. In his videos Mike talks a lot about grounding safety misinformation.

He says that properly grounding the circuit will not open the breaker in the event of a fault.

Then, I ran into this sentence in the DOE (Department of Energy) Electrical Safety Handbook page 55:

4.4 BONDING
Caution shall be taken to ensure that the main bonding jumper and equipment bonding jumper are sized and selected correctly. Bonding completes the grounding circuit so that it is continuous. If a ground fault occurs, the fault current will flow and open the overcurrent protection devices.

Is this the kind of misinformation which Mike Holt is referring to in relation to grounding?

 

[LarryFine]

It depends on the kind of fault you're referring to. For a fault to earth, no, a (non-GFCI) breaker won't trip. For a fault to a properly-bonded metallic surface, yes, it will.

The bond between the EGC and the neutral makes sure that a line-to-ground (EGC) fault will make the breaker behave as it would with a line-to-neutral (or -line) fault.

 

[AC\DC]

I believe what your referencing on mike holts is him talking about the GEC (Grounding Electrode Conductor) this won't clear a fault.
As larry said any fault to a properly bonding metal pathway back to source will trip a breaker.

Maybe I am misunderstanding you. do you have the page he talking about I have his books I could read what your reading.Looks like its a video can you post that one please.

 

[ericsarratt]

Thanks for the help. He talks about it in this video at 34:52

Then about a minute later at 35:42 he talks about driving a ground rod and connecting 120 volts to it; it doesn't trip the breaker.

 

[AC\DC]

yes that a GEC it does nothing for clearing a fault DOE is not talking about GEC.

 

[ericsarratt]

Okay. Thank you.

So it is the grounds connection to the neutral that causes the bonded conductors to trip the breaker? Correct?

 

[Sberry]

Yes that is correct. The big pic post above is pretty good.

 

[ericsarratt]

Yes that is correct. The big pic post above is pretty good.

"big pic post above"? Would you clarify.

Do you mean LarryFine's post?

 

[ActionDave]

Okay. Thank you.

So it is the grounds connection to the neutral that causes the bonded conductors to trip the breaker? Correct?

If you want to be able to discuss this topic in depth it would serve you well to reserve the term Ground for anything that has to do with a connection to the earth and use the term Equipment Ground for anything to do with fault clearing.

 

[ericsarratt]

If you want to be able to discuss this topic in depth it would serve you well to reserve the term Ground for anything that has to do with a connection to the earth and use the term Equipment Ground for anything to do with fault clearing.

Okay.

 

[jaggedben]

... I ran into this sentence in the DOE (Department of Energy) Electrical Safety Handbook page 55:

4.4 BONDING
Caution shall be taken to ensure that the main bonding jumper and equipment bonding jumper are sized and selected correctly. Bonding completes the grounding circuit so that it is continuous. If a ground fault occurs, the fault current will flow and open the overcurrent protection devices.

Is this the kind of misinformation which Mike Holt is referring to in relation to grounding?

No. See where I highlighted that the quote isn't actually about grounding?

A lot of people are confused by the fact that 'ground' and 'grounding' are used to mean both actual connections to earth and things that do not do that.

Typically (but not always) in this country and in the NEC we do two different things with power circuits.
1) Connect one of the circuit conductors to exposed metal parts (conduit, boxes, other metal in the building, etc.)
2) Connect that same circuit conductor to the earth with an electrode (which also connects the bare metal parts to earth when (1) is done)*

What Mike is trying to get across is that doing (2) does not accomplish (1) and is therefore unsafe when safety devices require (1).

The confusion arises because a lot of (1) is traditionally referred to as 'grounding' because it is assumed that (2) will also be done. But it is the bonding (1), not the grounding (2) that performs the most important safety functions like opening overcurrent devices. For example, the 'equipment grounding conductor' really performs bonding, not grounding. For another example, if a hot conductor contacts bonded parts and trips a breaker, that's typically refered to as a 'ground fault' even though the ground had nothing to do with it.

*(When no circuit conductor is bonded/grounded, the NEC still generally requires bare metal parts to be grounded.)

 

[jaggedben]

If you want to be able to discuss this topic in depth it would serve you well to reserve the term Ground for anything that has to do with a connection to the earth and use the term Equipment Ground for anything to do with fault clearing.

Or even better, use 'bonding' when generally referring to fault clearing, and 'equipment ground' (EGC) specifically as used in the code for bonding electrical equipment. A bonding jumper to water pipes is not an equipment ground.

 

[winnie]

He says that properly grounding the circuit will not open the breaker in the event of a fault.

Then, I ran into this sentence in the DOE (Department of Energy) Electrical Safety Handbook page 55:

4.4 BONDING
Caution shall be taken to ensure that the main bonding jumper and equipment bonding jumper are sized and selected correctly. Bonding completes the grounding circuit so that it is continuous. If a ground fault occurs, the fault current will flow and open the overcurrent protection devices.

Except for a language error, that DOE handbook is correct.

There are 2 factors, grounding and bonding. _Bonding_ is what creates a low impedance path so that a fault will trip an over current device.

Connection to soil (grounding) does not create this low impedance path, and is not relevant to tripping the OCPD.

The same metal gets both grounded and bonded, and the bonded path is often called a ground circuit. A fault to bonded metal is called a ground fault.

But it is the bonding that is important for tripping the OCPD in the event of a fault.

Jon

 

[ericsarratt]

For example, the 'equipment grounding conductor' really performs bonding, not grounding. For another example, if a hot conductor contacts bonded parts and trips a breaker, that's typically refered to as a 'ground fault' even though the ground had nothing to do with it.

Thanks!

 

[ericsarratt]

Except for a language error, that DOE handbook is correct.

There are 2 factors, grounding and bonding. _Bonding_ is what creates a low impedance path so that a fault will trip an over current device.

Connection to soil (grounding) does not create this low impedance path, and is not relevant to tripping the OCPD.

The same metal gets both grounded and bonded, and the bonded path is often called a ground circuit. A fault to bonded metal is called a ground fault.

But it is the bonding that is important for tripping the OCPD in the event of a fault.

Jon

So a fault which connects to the low impedance path causes more electricity to flow, i.e. more amps, which then trips the breaker?

 

[LarryFine]

So it is the grounds connection to the neutral that causes the bonded conductors to trip the breaker? Correct?

Yes. The EGC protects people by tripping the breaker before someone gets a shock.

(A GFCI, on the other hand, protects people by tripping after someone gets a shock.)

 

[LarryFine]

So a fault which connects to the low impedance path causes more electricity to flow, i.e. more amps, which then trips the breaker?

Yes again. Earth is not conductive enough to carry enough current to trip even a 15 amp breaker.

An EGC can be smaller than the circuit conductors because a fault is (usually) a short-term event.

 

[Sberry]

The thread right above this one has a fairly clear explanation. Its simply worded.

 

[Sberry]

(B) With Circuit Conductors. By an equipment grounding conductor contained within the same raceway, cable, or otherwise run with the circuit conductors.
NEC HANDBOOK COMMENTARY;
One of the functions of an equipment grounding conductor is to provide a low-impedance ground-fault path between a ground fault and the electrical source. This path allows the overcurrent protective device to actuate, interrupting the current. To keep the impedance at a minimum, it is necessary to run the equipment grounding conductor within the same raceway or cable as the circuit conductor(s). This practice allows the magnetic field developed by the circuit conductor and the equipment grounding conductor to cancel, reducing their impedance.
Magnetic flux strength is inversely proportional to the square of the distance between the two conductors. By placing an equipment grounding conductor away from the conductor delivering the fault current, the magnetic flux cancellation decreases. This increases the impedance of the fault path and delays operation of the protective device.

 

[ericsarratt]

(B) With Circuit Conductors. By an equipment grounding conductor contained within the same raceway, cable, or otherwise run with the circuit conductors.
NEC HANDBOOK COMMENTARY;
One of the functions of an equipment grounding conductor is to provide a low-impedance ground-fault path between a ground fault and the electrical source. This path allows the overcurrent protective device to actuate, interrupting the current. To keep the impedance at a minimum, it is necessary to run the equipment grounding conductor within the same raceway or cable as the circuit conductor(s). This practice allows the magnetic field developed by the circuit conductor and the equipment grounding conductor to cancel, reducing their impedance.
Magnetic flux strength is inversely proportional to the square of the distance between the two conductors. By placing an equipment grounding conductor away from the conductor delivering the fault current, the magnetic flux cancellation decreases. This increases the impedance of the fault path and delays operation of the protective device.

Cool! Thanks!

I've thought about getting the NEC handbook.

North Carolina is on the 2020 NEC. Should I get the 2020 version of the handbook or the 2023?