Equipment Grounding for Ungrounded System

[bobby ocampo]

On an HRG or ungrounded system it will do that, but it won't do that on a solidly grounded system.

It will have the same effect in solidly grounded specially if the fault is an ARCING GROUND FAULT. This fault is very low most of the time lower that the ampere trip rating of the OCPD. Even with EGC the OCPD may not trip.

This is the reason for the requirement of a ground fault protection in Article 240 for feeder of 1000amps or more and 150 volts to ground or more on solidly groundd system.

The type of fault does not change anything. There will still be a voltage between the point of the fault and the earth.

The voltage drop in the grounding conductor is very low because requirement is to use a low impedance path to earth during ARCING GROUND FAULT. Current is lower than the ampere trip rating of the OCPD and computing for the voltage drop will be very low V=IR. Resistance is very small per 10000 feet. Current is very low, lower than the ampere trip rating of the OCPD on an ARCING GROUND FAULT.

Electric shock will come from the energized metal piece not connected to ground similar with the UNGROUNDED AND HRG and not on the ARCING FAULT CURRENT because this current is very low.

 

[tryinghard]

To explain this is to first ask if you have seen a HIGH RESISTANCE GROUNDED SYSTEM. You will know what I am saying if you understand the function of HRG.

I am not debating with you about a HRG system only ungrounded along with your claim that earth will drain or route fault current in premises wiring.

Answer my questions, and prove your claim!

 

[bobby ocampo]

I am not debating with you about a HRG system only ungrounded along with your claim that earth will drain or route fault current in premises wiring.

Answer my questions, and prove your claim!

It has the same explanation. Or to prove it yourself you can experiment don't worry its safe provided you use a voltmeter. There will be very small or no fault current or no arc flash hazard in an ungrounded system.

Please read comments of others in the thread.

This means that connection to earth will really reduce the energized metal piece to ground potential.

On an HRG or ungrounded system it will do that

 

[bobby ocampo]

You can also read INDUSTRIAL POWER SYSTEMS HANDBOOK BY BEEMAN.

 

[tryinghard]

It has the same explanation. Or to prove it yourself you can experiment don't worry its safe provided you use a voltmeter. There will be very small or no fault current or no arc flash hazard in an ungrounded system.

Please read comments of others in the thread.

I have and I disagree with your claim.

 

[bobby ocampo]

I have and I disagree with your claim.

Ok we agree to disagree. Have worked in a glass plant and petrochemical plant where they have ungrounded system. Let's just hope that nobody gets electrocuted because of non connection to the ground. May they rest in peace.

 

[tryinghard]

Ok we agree to disagree. Have worked in a glass plant and petrochemical plant where they have ungrounded system. Let's just hope that nobody gets electrocuted because of non connection to the ground. May they rest in peace.

You may feel the need to pre-qualify your experience, so be it.

A code compliant ungrounded system includes its case and non current-carrying items bonded and grounded 250.4(B).

A code compliant ungrounded system includes fault detection as ?indication and or annunciation? 250.21.

Both of these are extremely important! There should be electrocution problems if you have not done these, my systems will have them!

 

[bobby ocampo]

You may feel the need to pre-qualify your experience, so be it.

A code compliant ungrounded system includes its case and non current-carrying items bonded and grounded 250.4(B).

Yes it should be bonded and GROUNDED for safety.

A code compliant ungrounded system includes fault detection as ?indication and or annunciation? 250.21.

Fault detection is to prevent second line-to-ground fault which I agree is also very important in an ungrounded system.

Both of these are extremely important! There should be electrocution problems if you have not done these, my systems will have them!

I agree and as you said this included GROUNDING TO EARTH (GROUNDED)

 

[tryinghard]

I agree and as you said this included GROUNDING TO EARTH (GROUNDED)

Of course!

 

[weressl]

The OCP will open!

IF the EGC is intact. Since EGC does not take part in the circuit's operation, until its needed you don't really know its condition, so if it is dosconencted it will go unnoticed.

 

[tryinghard]

IF the EGC is intact. Since EGC does not take part in the circuit's operation, until its needed you don't really know its condition, so if it is dosconencted it will go unnoticed.

This will not happen with qualified journeymen electricians working on it, but it will likely happen with non qualified workers working on it!

 

[weressl]

This will not happen with qualified journeymen electricians working on it, but it will likely happen with non qualified workers working on it!

The issue has nothing to do with the installer. Equipment does fail and there is no mechanism to warn of that failure, except some exotic ground continuity monitors that are only in use in special cases. Your argument is a non-sequitur.

 

[tryinghard]

The issue has nothing to do with the installer. Equipment does fail and there is no mechanism to warn of that failure, except some exotic ground continuity monitors that are only in use in special cases. Your argument is a non-sequitur.

It most certainly does involve installers either going in new or existing. EGC?s do not fail they may be taken out or eliminated some how buy unqualified personnel.

Your claim is not true in premises wiring with SDS?s and NEC applications. In this environment of 480V and under the earth ground is less important than the equipment bonding to source especially with a grounded system.

You need to look at math scenarios of high voltage, service utility, and power generation compared to premises wiring of 480V or less to understand better the functions/purpose of earth connection and bonding to source.

Your claim is dangerously supporting (or at least over-emphasizing) the use of earth for effective ground fault path and draining; not to those who know better but to those who don?t!

 

[weressl]

It most certainly does involve installers either going in new or existing. EGC?s do not fail they may be taken out or eliminated some how buy unqualified personnel.

Your claim is not true in premises wiring with SDS?s and NEC applications. In this environment of 480V and under the earth ground is less important than the equipment bonding to source especially with a grounded system.

You need to look at math scenarios of high voltage, service utility, and power generation compared to premises wiring of 480V or less to understand better the functions/purpose of earth connection and bonding to source.

Your claim is dangerously supporting (or at least over-emphasizing) the use of earth for effective ground fault path and draining; not to those who know better but to those who don?t!

EGC's are no diffrent than any other mechanical component and if you claim that they are immune to failure you are engaging in intellectual dishonesty. BTW what is a 'how buy'?

Prove your claim.

I did.

Not true.

 

[brian john]

It most certainly does involve installers either going in new or existing. EGC?s do not fail they may be taken out or eliminated some how buy unqualified personnel. !

1st supposedly qualified personnel can mess up also AND DO all the time.

2nd Components do fail due to a variety of circumstances outside the installers control.

 

[weressl]

1st supposedly qualified personnel can mess up also AND DO all the time.

2nd Components do fail due to a variety of circumstances outside the installers control.

Logic, reason?!

What a concept!

 

[tryinghard]

EGC's are no diffrent than any other mechanical component and if you claim that they are immune to failure you are engaging in intellectual dishonesty. BTW what is a 'how buy'?

Prove your claim.

Not true.

Ground use:
Ungrounded system, 250.4(B)(4) & last sentence
Grounded system, 250.4(A)(5) & last sentence

Ground purpose:
Ungrounded system, 250.4(B)(1)
Grounded system, 250.4(A)(1)

Equipment ground to enable:
Ungrounded system, 250.4(B)(2) through (4)
Grounded system, 250.4(A)(3) through (5)

If grounding for the wrong reasons:

Ohms law I=E/R will show you why earth cannot be an effective ground fault path in premises wiring.

Ohms law will show you why earth can contribute to ground plane and OCP in high voltage environments.

Do the math!

 

[tryinghard]

The issue has nothing to do with the installer. Equipment does fail and there is no mechanism to warn of that failure, except some exotic ground continuity monitors that are only in use in special cases. Your argument is a non-sequitur.

Earth cannot replace the function of equipment grounding and bonding in premises wiring.

Earth cannot have zero potential with non current carrying items in an electrical system.

In premises wiring the equipment grounding is really the ground plane; it is supposed to be an effective ground fault path.

I do not install a ground to earth for this reason (to allow zero potential with non current carrying items) at all.

 

[bobby ocampo]

It most certainly does involve installers either going in new or existing. EGC?s do not fail they may be taken out or eliminated some how buy unqualified personnel.

If EGC will not be properly sized may cause it to become a fuse and therefore be removed out untintentionaly.

Your claim is not true in premises wiring with SDS?s and NEC applications. In this environment of 480V and under the earth ground is less important than the equipment bonding to source especially with a grounded system.

It is dangeours and very hazardous to say that the earth connection is less important. Arcing Ground Faults are single line to ground faults in SOLIDLY GROUNDED SYSTEM that are smaller in magnitude the the bolted single-lline-to-ground fault. This ARCING GROUND FAULT is most of the time even less than the ampere trip rating of the OCPD. Even with the best BONDED EGC the OCPD will not operate because the ground fault is still too low. However due to this ARCING GROUND FAULT, the accidentally metal piece of equipment will now be energized and if the energized metal piece of equipment is not conneted to the EARTH will cause electric hazard.

You need to look at math scenarios of high voltage, service utility, and power generation compared to premises wiring of 480V or less to understand better the functions/purpose of earth connection and bonding to source.

In premises wiring of 480 volts, line-to-neutral voltage is more than 150 volts to ground. The code requires a ground fault protection for OCPD rated 1000amps or more for the protection against ARCING GROUND FAULT. Maximum setting of GROUND FAULT PROTECTION only up to 1200 amps. If the main cirucuit breaker in a premises wiring 3000Amps this means that ground fault due to ARCING will have current of less than 3000amps. If the main circuit breaker has not ground fault protection, it means that it will not trip on an ARCING GROUND FAULT. If the arcing ground fault energizes the metal part and it is not connected to earth then there is a danger of electric shock. It is important to note that ARCING GROUND FAULT is low enough NOT TO OPERATE the OCPD despite the bonded EGC.

Your claim is dangerously supporting (or at least over-emphasizing) the use of earth for effective ground fault path and draining; not to those who know better but to those who don?t!

Most of the people who are working near energized equipment or appliances are people who don't know better. Only small percentage of the population are Electrical Engineers and Electricians. These people who don't know better would have to be protected against the hazards in the use of electricity.

 

[bobby ocampo]

Earth cannot replace the function of equipment grounding and bonding in premises wiring.

Earth is not a replacement but a PART of equipment grounding and is never LESS IMPORTANT to reduce hazard of electric shock. BOTH ARE IMPORTANT.

Earth cannot have zero potential with non current carrying items in an electrical system.

Earth is required in NEC. Earth is considered zero potential for safety. This can be proven on a single-line-to-ground fault in an Ungrouded system and HRG.

In premises wiring the equipment grounding is really the ground plane; it is supposed to be an effective ground fault path

I do not install a ground to earth for this reason (to allow zero potential with non current carrying items) at all.

This is a violation of the code.