IS CONNECTION TO EARTH OTHER THAN THE SERVICE EQUIPMENT HELPFUL IN PROTECTING SHOCK AND ELECTROCUTION PROVIDED IT IS BONDED

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bobby ocampo

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What are your thoughts on the importance of connection to earth?
What do you think is the intention of the code why neutral is bonded in the the Service equipment?
 
It matters using basic electrical engineering. I hope that the moderators will not close the thread. In our example we have seen that if a current carrying conductor is grounded or connected to earth the potential to ground is reduced to a value approaching zero.
Now what will happen if there is another ground rod in the panel connected to ground. Let's assume first that the transformer is ungrounded and connection to ground happens in the metal panel. SEE ILLUSTRATION wi

What will be the touch potential assuming the metal enclosure has a low resistance? Will the person touching the metal be electrocuted? Is the ungrounded converted to corner grounded and therefore the metal panel will have touch potential approaching zero?
Will this prove that connecting to earth helps? We can only request that this discussion will not be censored. They can experiment to prove this using a voltmeter of a light to measure touch potential. This is for unloaded delta. What happens if the transformer is loaded will be in my next illustration if it will not be censored.

The connection to ground will definitely not operate the OCPD even with load. Reference IEEE 142 Chapter 1 and Beeman, Industrial power systems handbook.

Appreciate discussing with you. Hope the viewers appreciate
 

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The fault to the grounded enclosure simply converts an ungrounded delta system to a corner-grounded system. A person touching the enclosure wouldn’t even realize a fault had occurred.
Agree. is it clear that when the conductor is connected to ground the potential is at the same as the ground potential which is zero or approaching zero?
What is the potential to ground or voltage to ground if the line is not yet grounded? Will you be electrocuted if there is no connection to ground?
 
It’s all explained in the IEEE green book and summarized in section 250.4
You stated out asking about why services are grounded and got off into ungrounded systems. Stay on topic
 
For the OP, you have mentioned ground rods several times, what is the minimum ground rod resistance?
 
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IS CONNECTION TO EARTH OTHER THAN THE SERVICE EQUIPMENT HELPFUL IN PROTECTING SHOCK AND ELECTROCUTION PROVIDED IT IS BONDED?​


You ask about a bonded transformer, then provide a diagram, that shows a floating transformer output coil? Bonding a case to a ground rod, does not mean that the transformer coil is bonded, and realistically does nothing.

I would suggest that you obtain a copy of Soares Book On Grounding. It has lots of illustrations and detailed explanations of all system types and how and why they are treated the way they are.
 
What are your thoughts on the importance of connection to earth?
What do you think is the intention of the code why neutral is bonded in the the Service equipment?
Mike Holt has some old videos available online of different techniques of testing GES resistance.

And he does in fact show the lower the earth resistance of a GES at a service in the case of an open neutral it will reduce touch potential to conductive objects.

But this is not the main point of the service neutral being grounded. Thats the reason the code only requires a 25ohm with one rod or 2rods and a 1000ohms. They don’t care. The fact that it’s grounded at the service has no significance in safety of personnel.

Dirt and ground rods play no role of safety against personnel in the scope of NEC.
 
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14 years is a long time to be studying how and why to ground and bond a transformer. A used copy could be had on ebay for pretty cheap, but one would have to assume that he doesn’t want to know that bad. I guess that the all caps, should have been a clue.
 
14 years is a long time to be studying how and why to ground and bond a transformer. A used copy could be had on ebay for pretty cheap, but one would have to assume that he doesn’t want to know that bad. I guess that the all caps, should have been a clue.
I am not worried about the all caps or the strange grammar. I think the guy does not do English perfectly. Part of his problem may be not being able to communicate adequately what his issue is in English. I am certainly having figuring out what it is he is trying to say.
 
What is the potential to ground or voltage to ground if the line is not yet grounded? Will you be electrocuted if there is no connection to ground?
If you have an ungrounded system, and an enclosure containing said system that is not connected to Earth, it is still very unlikely you would receive a shock by touching that enclosure. There is a possibility, very slight at low voltages, that you would have some capacitive charging of the enclosure and could be shocked when touching it. Bonding everything together and connecting to Earth generally provides equipotential and eliminates these rogue capacitive charging currents between different components and or the Earth. These concerns would be much more pronounced at medium and high voltages, very unlikely at under 600 volts.
 
With a small ungrounded system, it is probably safer than a grounded system in that you would have to touch two of the circuit conductors to receive a shock, unlike a grounded system where you are shocked by touching a circuit conductor and the earth or anything connected to the earth. This is the very reason ungrounded systems are used in operating rooms as it reduces the risk of a shock to a patient under conditions where micro-amps of current can be fatal.

However as the systems get larger in terms of both kVA capacity and length of wire and amount equipment connected to the system, the capacitance current to ground goes up. I have been able to pull in a solenoid voltage tester measuring from an ungrounded conductor of a large 480 volt system to earth, and the current required to pull in the solenoid is more than enough to result in a fatal shock.
 
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I was a machinist mate (nuclear machinist today) in the Navy. Ships electrical was 440 V 3 ph ungrounded, we were taught even though ungrounded we could get shocked due to capacitance. Us nukes understand that, the topside guys they just said don’t touch.
 
Additional grounding electrodes gets into a multi grounded situation which can cause serious issues. I think Mike Holt has done a great job of shedding light on “stray voltage” (technically stray current) which is either caused by or made worse by multiple grounds. With multiple rods present there are multiple paths and fault current can take multiple, sometimes undesirable paths. More grounds is not better.

This runs contrary to what utilities do which is the opposite theory…you can never have too many grounds,
 
For me I think the issue is advocating or advising Earthing does anything safety related. If it's a safety concern, saying it's Earthed only conveys no information to me. And then if trying to say 'Earth it for safety' I would view it as a dangerous misunderstanding (typically coming for someone without an electrical background).

That's how the statement would come to me, from someone who I do not expect to have a deep electrical background. So the issue of basically misinstructing the non technical audience jumps out at me. The next guy is just going to report what he heard or saw at the last instance 'I earthed it for safety'.

My concern would be, if you're going to touch it with your own hands, you'll figure it out I have no doubt there. My guess is you're writing in a manner of advising some else to touch it with their hands. The system is safe (for you) to touch because it is Earthed.

That statement is false and the opposite is true. Earthing is neither necessary or sufficient to make the electrical system safe.

Earthing will have a duty to perform dumping lightning strikes and utility faults, overvoltages, during which time there will be a substantial step and touch potential surrounding the earthing system, as it functions now necessary. Which is why the bonding mats have to be connected to the switchgear as well as everything else, to limit the touch potential where the man must also function and now touch (feet on the concrete, throw the switch).

Just saying you Earthed something bypasses everything else necessary to make it safe. That's what message the idiot public should get. There's a lot more to it. Hire pros if you want the thing touched.
 
If the electrical industry used the correct terms instead of ground there would not be the misunderstanding we have today.
 
If you tried to convey your information using only equipotential bonding, and how you did that to make it safe for you to touch, certainly would read better to my eye.

Discussing Earthing as safety related, made it all hard to read. I don't have any idea what the original objective was, what else was conveyed.
 
I am fine with people thinking it is grounded meaning it is safe. To me that means it has an ECG to carry fault current, sufficient to trip the upstream device. I don't expect anyone wants to know the detail of how. The convention is for grounding to mean per code, EGC and an OCPD, solidly grounded and not some unicorn floating system. The convention for grounded to mean safe, works imo, people also assuming pro work to code.
 
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