Tools are Grounded to Send the surge of electricty to earth
- Thread starter tom baker
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K8MHZ
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- Electrician
Re-draw your pdf with a couple of rods stuck in the dirt and show how that would have changed anything.
Here's the deal w/ earth grounding- it does not make hazardous voltage "disappear" in the advent of a fault- only a protective device opening, which in turn cuts power to the fault, the conductors themselves eventually burning open, or power being cut by qualified personnel in the advent of an emergency,( note KH8MZ's 59 & 60 posts) can reliably do that. Power will continue to flow no matter how many rods there are and present a hazard until one of those happens. This has been studied to death and it was concluded eons ago that soil won't absorb electrons and trip an ocpd, nor is it a guaranteed reliable path.
K8MHZ
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- Electrician
It's your drawing, and you didn't show the two points of contact that were present at the time of the shock. Let's say it was because the neutral was opened by mistake, what would that matter? You need to show a before with points of contact and an after, also with points of contact, only with ground rods present and show how they would have prevented the shock.
Also, please indicate if the post in the drawing is metal or wooden.
Thank you.
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electrofelon
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- Cherry Valley NY, Seattle, WA
It sounds like you are describing an ungrounded system, with no grounding electrode connected to the non current carrying metal parts. In this situation, I still see the grounding electrode as providing a very minor role. You would still need everything bonded together to reduce touch potential between metal parts, allow ground fault detectors to function, and provide a low impedance path for a second fault. If you have that done, I highly doubt that bonding system will not have been already "accidentally" bonded/referenced to ground through pipes, attachment to concrete, direct contact, etc.
K8MHZ
Senior Member
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- Electrician
Since no grounding at all is shown, the drawing is of an ungrounded system. Or it is a grounded system, and the MGN wasn't indicated.
We also don't know the voltages, important to determine the shock potential between two points.
Also be advised that this kind of installation would not be allowed in the US, as drawn.
K8MHZ: The electrician was on the metal post. If earth link shorting all overhead lines was grounded, it and the metal post would be at same potential (as metal post was also fixed to ground), no matter whether any load current flowing in overhead neutral line or not and so the electrician would not have received a shock.
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K8MHZ
Senior Member
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- Electrician
Good info. If the electrician was working on a metal post, why was he not wearing PPE?
How can that post be a path back to the source of the electricity as drawn? You are not showing something in your drawing. In order for there to be a potential between the ungrounded post and the ungrounded system, there must also be another fault to ground that you are not showing in your drawing.
Edit to add:
If the electrician was working in contact with a metal post, why was he not wearing PPE? PPE and not having people that don't know enough not to open a neutral and leave the other conductor's disconnect closed should be your main concern. Requiring qualified personnel and PPE will go MUCH farther to protect people than sticking rods in the ground, which won't help much at all.
What is the average ground resistance for one rod in India? It's over 1000 ohms here in Michigan and it rains all the time.
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K8MHZ
Senior Member
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- Electrician
If you look through the lens of the code, you would see the solution to avoid the accident mentioned in post # 45 contains a code violation, which K8MHZ also missed.
What is it?
You are only assuming I missed something. I haven't mentioned everything I saw wrong with your drawing, that's why I have stated that something is missing from it.
For one thing, there is no safety bonding done at all, according to your drawing. If that's what you are getting at by using the term 'grounding', please don't. It just make things confusing.
Your drawing is a mess of code violations, your foreman wasn't qualified to be working on the system, the person on the pole that got shocked was not following safety procedures and yet you still think that grounding is the answer. It's not. Many have tried to explain this to you, you ignore them. I have asked several times for a complete drawing, it hasn't been provided.
Maybe we should get you back to basics. Do you know the difference between bonding and grounding, why they are different and what the intent of each one is?
I don't think you do, and it is causing you to make assumptions that are incorrect.
I also don't think I am alone in my thoughts. What I think is that the gentlemen on this forum have grown tired of you asking a question and then refusing to accept the answer.
Is the 'foreman' that opened a neutral and left the hot conductors live at the first point of disconnect still a foreman? He shouldn't even be working on electrical systems.
Wasn't it you that suggested a crane bucket be grounded because of a fatal lightning strike at a construction site a while back?
Before we continue, I would like an honest answer to the following:
Do you post questions and make suggestions here to learn and improve yourself, or do you do it to try to make the rest of us look like we are not familiar with our work?
If you really want to learn, all of us have the sincere desire to help you in any way we can. If you are just trying to be argumentative, you are in the wrong place to do that, especially when it comes to safety issues.
There were at least two grounds one formed at metal post and other by grounding the shorting earth link (per accident prevention suggestion in post 45). But per code there shall be only single ground. So the grounds were to be bonded together in addition to avoid shock to electriccan on post. I got this insight by discussion in forum. Thanks.If you look through the lens of the code, you would see the solution to avoid the accident mentioned in post # 45 contains a code violation, which K8MHZ also missed. What is it?
K8MHZ
Senior Member
- Occupation
- Electrician
Your drawing shows the metal post as being ungrounded, that is not assumed, it is specifically indicated by your note. Now you are saying the metal post was grounded. You can't have it both ways. Your drawing shows an ungrounded system with a neutral and no faults anywhere to ground upstream of the pole. That means no path from the ground or the pole or your car back to the source of the electricity, which can't be if the worker on the pole got shocked. The pole posed a hazard because the metal parts were not bonded to the neutral, the pole was indeed grounded contrary to your drawing, and I will bet that you have a grounded system with no ECG, not an ungrounded system with a neutral.
Also, there is nothing in the code that says there can only be a single ground. There can be many grounds, and even several grounding systems for different purposes. For example, a ground system for lightning protection of a radio tower, a ground system used as a counterpoise for an antenna, and an AC mains ground, all at the same premises. The code requires all of them to be bonded together, it does not prevent the installation of any of them.
Bonding is the means for personal safety. Grounding is for surge protection and voltage to ground reference until you get into the 63kV plus range.
For some reason you either to not understand this, or you refuse to accept it.
Also, qualified personnel is crucial to safety. A qualified person would not have opened a neutral on a live system. A qualified person wouldn't have fallen if they were wearing fall protection.
K8MHZ: Note in post 46 of 'not grounded' refers to earth link and not metal post. Sorry again for poor quality of drawing. Also I might have used 'single ground reference' instead of simply saying 'single ground'. Note a person is liable to get a shock when he stands on ground and in contact with metal surface of a system with phase fault to metal surface which is bonded but not grounded.
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K8MHZ
Senior Member
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- Electrician
K8MHZ
Senior Member
- Occupation
- Electrician
Here is another one:
K8MHZ
Senior Member
- Occupation
- Electrician
He does.
Sahib, if the metal pole was bonded properly back to the source thru the egc, the breaker would have opened already and de-nergized the ckt, thus preventing the employee from getting shocked in the first place. Adding a ground rod or 2 or 3 to the base of that pole would not help a thing in the absence of bonding.
Pay attention to the pics that K8MHZ posted.
Back to square one. See post 26.
:happyno:Yeah, I don't think so:
Which was answered perfectly by two esteemed moderators here:
As for a standard ocpd on short runs, adding a rod is on it's face pointless and useless- still a poor path back to source and breaker won't trip. And remember that the dangerous current doesn't disappear down the rod and the breaker still has to trip to eliminate the hazard. Gfci doesn't need any help to do anything (as if a rod would help it anyway)- the amount of current it trips on is considered harmless to most everybody.
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