grounding, not enough

[m singer]

"Grounding rods are completely useless for preventing shock and that was never their purpose anyway. "


Why are they required then, what is their role?

Sorry for the very late reply. A PE at a local electrical utility told me that the purpose of a grounding rod is to make the potential at the service entrance to the same as the ground at the transformer. A ground rod is not a low impedance path back to the source and therefore generally will not trip a breaker.


Mike Holt gives a good explanation starting just after 19:30 min

https://www.youtube.com/watch?v=3vvvv5QVZoA

[timjimbob]

In my case, pole transformer ground was nothing near zero volts so, in theory, my meter/ service entrance voltage should be jacked up to utility transformers' above zero value. Not buying that.

[micdundee]

had a case where I found there was just over 50 volts on neutral from power company after several hours of a "search and destroy" volt mission. The power co. was sympathetic but said could do nothing, because it was probably someone, up the line, for who knows how many miles, putting the volts on the line.

[frank shelley]

I chased a shocking water issue once that only occurred when the wall furnace was on. I had no hair on my head from me pulling it out finding the issue. In the end a Fan wire in between the furnace cabinet that was buried you couldn't see was rubbing and grounding to the cabinet. When the fan would switch on voltage would bleed through the copper LP gas line passing to the water heater.

[timjimbob]

Had a long time customer call about an issue with the DISH installer. They had plugged their grounded receiver into the master bath plug. Shower of sparks blew from the plug. Wanted me to figure what was going on.

DISH antenna coax was well grounded to the outside meter equipment. The house was 10 year old pier and beam with wood floors. I found a romex cable staple that had punctured the insulation and was tying hot to ground conductor in the attic.

Well this can happen but should have tripped the breaker. That puzzled me. Opened the breaker panel and found the romex ground connector not connected to busbar.
So all these years the electrical box screws were all 120 volts hot in the bathroom-lucky no one was killed.

Thinking back, some "don't care" electrician probably kept having the breaker trip and found if he un-connected the ground the breaker would stay on.

[BNME8EZ]

I had a customer complaining about lights blinking when the compressor started on their heat pump, like that has never happened before right. I dig in to it, it has a start kit that is working properly, the voltage doesn't dip on start up, amp draw on start up was faster than my Fluke would capture at 100/sec recording value. I checked everything I could think of and came up blank at every turn. For some reason, out of desperation I guess, I stuck one probe on the ground wire and put the other probe in the ground, I had 60+ volts, what. How does this happen. I start checking connections all the way back to the panel and had the same results all the way. I called the city and explained the issue. They sent out a couple lineman. I told them what I found, they pulled the meter and checked line-line, line to neutral, line to ground neutral to ground, all readings normal. The guy said I don't see a problem. I said put one probe on ground and give me the other. So he did and I stuck the probe in the dirt. He said what did you do, so I showed him the probe in the dirt. He went WTF. I said that's what I thought. They dug for over an hour and finally found the ground plate was rotted off at the pole. They fixed that, the reading neutral to ground went away and so did the light flicker on compressor start.

[DavidDeBord]

Had an issue that electrified the water pipes, and cast iron pipes in a rent house. We could not bond or add enough grounding rods to eliminate the problem. Two more 6 foot rods, ties to underground copper pipe to back yard hydrant. All existing grounding was proper. Had to have tenants move out because of shocking shower.

Problem was bad neutral at pole. power company says they are not liable for condition of power quality coming into the residence.

I felt exposed to a law suit even though I had done everything I can to safeguard my tenants.

How should I make this situation safer, in future situations.

A "Bad Neutral at the Pole" is the responsibility of the Utility Provider, & Yes Sir! ...... It will Absolutely cause all kinds of hazardous problems within the building that is being sup[plied by the Utility.

I had a Customer with the same problem of getting shocked in various areas, & finally traced it out to the Pole. The Utility Provider is Duke Energy, & I called the Electrical Service Department, & they came out within two hours & fixed "Their Problem".

As far as Your "Utility" timjim, ... I'd go to the "Higher Political, & Governing Powers in Your State", & File a Complaint, as well as Request/ Subpoena, any document related to this incident, so as to show that none of it was your fault.
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Oops, ..... I just saw the date on this post, I replied to the initial post, cuz' the Topic came up as "New"/ "Active".

[DavidDeBord]

I had a customer complaining about lights blinking when the compressor started on their heat pump, like that has never happened before right. I dig in to it, it has a start kit that is working properly, the voltage doesn't dip on start up, amp draw on start up was faster than my Fluke would capture at 100/sec recording value. I checked everything I could think of and came up blank at every turn. For some reason, out of desperation I guess, I stuck one probe on the ground wire and put the other probe in the ground, I had 60+ volts, what. How does this happen. I start checking connections all the way back to the panel and had the same results all the way. I called the city and explained the issue. They sent out a couple lineman. I told them what I found, they pulled the meter and checked line-line, line to neutral, line to ground neutral to ground, all readings normal. The guy said I don't see a problem. I said put one probe on ground and give me the other. So he did and I stuck the probe in the dirt. He said what did you do, so I showed him the probe in the dirt. He went WTF. I said that's what I thought. They dug for over an hour and finally found the ground plate was rotted off at the pole. They fixed that, the reading neutral to ground went away and so did the light flicker on compressor start.

I gotta say, that the ground plate was made of "Piss Poor Materials" for it to have rotted BNM. When I've seen this problem at the pole, ... It's either been caused by Storm Damage, a badly leaning pole that stressed the connections, or damage caused by a negligent road crew as the bush hogged around the Pole.

Good Job, at finding the Customer's Problem, BNM, & I'm gonna file this one away in my Mental File Cabinet, for another possible problem at the Utility Pole.

[johnnyb]

All kinds of crazy things can go on with ground rods, pole ground wires , earth, sand (in the desert ) and the like but it is so very important to make sure that the ground and neutral are bonded to gether at the building service . I am not a fan of ground rods and the like but if the neutral and ground are not bonded then there may not bea good path for ground fault current to come to the transformer winding which causes the breakers to trip. If you have a solid ground and it is bonded to the neutral you can not have voltage difference on the neutral and ground wires. But if not you can have two girls that were detassling corn electrocuted on a field irrigation machine . SAd , Look it up in Indiana. 6 others e=went to the hospital trying to save them. All becasue of poor knowledge or poor maintenance .

[Sberry]

It seems to me that, electrically speaking; the neutral at the transformer out on the power pole is to the ground - the dirt - the Earth connection.

In other words: "the neutral" is not hard wired back to the power plant.

So how is it different if I ground the neutral wire at the building end of the wire or at the transformer side of the wire? Why won't a driven-rod ground at the service entrance work the same at it would if the grounding rod was out at the pole?

Hmmmm . . . . Now that I am thinking about it: there really isn't any such thing as a 'neutral' connection at the transformer - is there? Isn't the primary side just 'one leg to ground' ?

Can you tell me what grounding a neutral at the building end won't work?

Oh wait - you are saying "an energized neutral" - how do you mean that? Do mean mean energized Other than through a connected load? All neutrals are "energized" in any working circuit situation - right?

Whew! OK; your turn. <g>

I can see this needs work. Neutral is the center tap of this transformer. When it is interrupted the current looks for a return to it via any method it can, the earth is too resistive for this hence we have stray current.

[Sberry]

is there? Isn't the primary side just 'one leg to ground' ?

No, one leg to the center tap,,, the earth really for this discussion at this point doesnt have anything to do with that. The rods are simply to reduce some step potentials as the earth is full of stray current, leaky wires etc and hopefully to shunt lighting strikes to the earth instead of carrying them in to the structure. You can see this in strikes where it went "searching" for a path to earth especially when the system has been compromised or even disconnected,,, water wells often are the target due to being improperly wired and service not connected to the casing proper while the path takes the egc (equipment ground wire) to the motor.

[Sberry]

It seems to me that, electrically speaking; the neutral at the transformer out on the power pole is to the ground - the dirt - the Earth connection.

In other words: "the neutral" is not hard wired back to the power plant.

So how is it different if I ground the neutral wire at the building end of the wire or at the transformer side of the wire? Why won't a driven-rod ground at the service entrance work the same at it would if the grounding rod was out at the pole?

Hmmmm . . . . Now that I am thinking about it: there really isn't any such thing as a 'neutral' connection at the transformer - is there? Isn't the primary side just 'one leg to ground' ?

Can you tell me what grounding a neutral at the building end won't work?

Oh wait - you are saying "an energized neutral" - how do you mean that? Do mean mean energized Other than through a connected load? All neutrals are "energized" in any working circuit situation - right?

Whew! OK; your turn. <g>

I can see this needs work. Neutral is the center tap of this transformer. When it is interrupted the current looks for a return to it via any method it can, the earth is too resistive for this hence we have stray current.