$500.00 ground rod

[stickboy1375]

Hey I like doing it that way.--- 4 ways also

(me too) Shhhhh....

 

[Rockyd]

I'm calling thread pollution on that one, Stickboy! Maybe even an effort to HiJack? Wait, wait, wait... on those switches, was the ground screw on top or bottom of the switch?

This is still a thread about grounding, and the club of authourity ...trying to stay focused on the ground rod, and Ul violations

 

[Bulldog1401]

Ground rods

Ground rods

I see that the way that I have worded a few, if not most of my posts, has left a lot of room for misinterpitation of my meanings. If you read my post, and take them in the context that they were intended you will see that I have agreed with others about every major point in this discussion including that it is wrong to cut down ground rods. As for the 25 ohm thing, if it does not count, why is it mentioned at all? And if so, if the first rod does not achieve it, and the second does not have to achieve it, why drive the second? Read the commentary on 250.53(D)(2). I know that commentary is not enforceable, but the message is telling us to achieve 25 ohms to ground.

 

[iwire]

As for the 25 ohm thing, if it does not count, why is it mentioned at all? And if so, if the first rod does not achieve it, and the second does not have to achieve it, why drive the second? .

Bulldog, that is exactly the point

WHY 25 ohms?....even the people who write the code don't know.

No one disputes we have to follow the NEC, what we (at least I) have been questioning is the actual value of 25 ohms compared to 26 ohms or 2500 ohms.

Did you read the links to Mike Holt's feelings about this after spending a lot of time trying to find out about this subject?

Read the commentary on 250.53(D)(2). I know that commentary is not enforceable, but the message is telling us to achieve 25 ohms to ground

There is no other way to put it.

If you only had a concrete encased electrode with 1000 ohms of resistance it would meet code

If you only had a ground ring with 1000 ohms of resistance it would meet code.

If you only have two ground rods with 1000 ohms of resistance it would meet code.

However if you only have one ground rod it must have 25 ohms or less resistance.

Once you provide any type of second electrode you have satisfied the code.

 

[roger]

but the message is telling us to achieve 25 ohms to ground.

No it's not, it is simply saying to add a rod.

If 25 ohms or less of earth resistance cannot be achieved with one rod, pipe, or plate, another electrode (other than the metal piping that is being supplemented) must be provided.

It doesn't go on to say "until 25 ohms or less can be measured".


Click HERE for another opinion that two rods meet code regardless of the resistance.

Here is a graphic and some commentary from the link.

Author’s Comment:

No more than two ground rods are required, even if the total resistance of the two parallel ground rods exceeds 25 ohms.

Roger

 

[Bulldog1401]

Quoted from roger;

"No it's not, it is simply saying to add a rod."


"It doesn't go on to say "until 25 ohms or less can be measured".

"No more than two ground rods are required, even if the total resistance of the two parallel ground rods exceeds 25 ohms."

Please find this exact verbage in the NEC and Quote it to me. I believe you are quoting an interpetation, not a section of code.

 

[George Stolz]

Bulldog, he gave you that in this post.

Edit to add: Try reading Charlie's Rule, and then read the section again.

The CMPs have stated what their intent does not include for now - they've made it clear with their statements, they do not intend for more than two ground rods to be required. The words reflect that intent. I don't see how you can read it differently.

 

[Bulldog1401]

unless[/I] that path is able to reduce the voltage across your contact points.

If you are talking about an infinitely sustained sorce of voltage, such as line voltage, your application of the basic rules of parallel circuits hold water. But lightning, spikes, and other anomolies 9what we are actually talking about here) are more like capacitor.. short finite bursts of energy that causes current to flow. the largest part of the energy will be dissapated on the least resistive path. Lesser ammounts will be dissapated on hire resistance paths. Until the energy is spent, and the potential difference is zero. As this change occurs, the properties you mentioned.. current and voltage are variable, but to a degree, the resistance orf the circuit remains unchanged.

look at a lightning struck tree. clearly the whole tree was struck at once. clearly the energy took a narrow path of least resistance, causing the burnt spot. the whole tree and bark was not burnt, just the path that the energy traveled through to ground. With your theory, you would not be able to tell which path the energy took.



[

 

[roger]

Please find this exact verbage in the NEC and Quote it to me.

As George said, I already did. Click the link he provided.

If you want the exercise, drive as many as you want, the rest will drive the code required two and go home.

Roger

 

[Dennis Alwon]

The only thing that I can add that hasn't been mentioned 25 times is that every inspector on this forum and every electrician that we have heard from in the past has never been turned down for only 2 ground rods.

This apears to mean that every inspection jurisdiction out there interprets the code to say to add another grounding electrode if one can't satisfy the 25 ohm rule.

Everyone can't be reading this wrong.

Peace

 

[petersonra]

If you are talking about an infinitely sustained sorce of voltage, such as line voltage, your application of the basic rules of parallel circuits hold water. But lightning, spikes, and other anomolies 9what we are actually talking about here) are more like capacitor.. short finite bursts of energy that causes current to flow. the largest part of the energy will be dissapated on the least resistive path. Lesser ammounts will be dissapated on hire resistance paths. Until the energy is spent, and the potential difference is zero. As this change occurs, the properties you mentioned.. current and voltage are variable, but to a degree, the resistance orf the circuit remains unchanged.

look at a lightning struck tree. clearly the whole tree was struck at once. clearly the energy took a narrow path of least resistance, causing the burnt spot. the whole tree and bark was not burnt, just the path that the energy traveled through to ground. With your theory, you would not be able to tell which path the energy took.

Lightning is a high speed phenomenon. My guess is that the resistance in the circuits struck by lightning is not a significant factor, when compared to the inductive reactance. IOW, you could have zero ohms resistance to ground and it would probably react no differently when hit by lightning than if it were 500 Ohms of resistance.

 

[LarryFine]

. . . you could have zero ohms resistance to ground and it would probably react no differently when hit by lightning than if it were 500 Ohms of resistance.

I know I would!

 

[Bulldog1401]

As George said, I already did. Click the link he provided.

I did. Your first quote is from the code. Your second is not. That is the one that counts.

The code says 25 OHMS. It then says that a water pipe ground shall be supplimented by another electrode. If that does not measure 25 ohms, then you must drive one more rod. It does not now nor has it ever said what ever the ohms reading is at that time is good enough.
Find that sentence, either verbatum or in substance, and quote it. I bet you won't.

I had a very good friend of mine who is a far more experienced electrician get his job stalled for exactly this. He had thousands on the line and could not find the verbage I mentioned to counter the inspectors point. So he met the code required 25 OHM reading, and then passed.

Never had it happen to me or even heard of it happening to anyone else, but it did to him.

 

[Bulldog1401]

Lightning is a high speed phenomenon. My guess is that the resistance in the circuits struck by lightning is not a significant factor, when compared to the inductive reactance. IOW, you could have zero ohms resistance to ground and it would probably react no differently when hit by lightning than if it were 500 Ohms of resistance.

We are not talking about a direct strike. I stated that earlier in the post. No disrespect intended. A direct strike will do as it pleases and destroy anything in its path. We are talking about spikes, other anomolies, and the lesser effects of stray voltage for lack of a better term, from lightning, which would be handled by the grounding system. Again, no disrespect intended.

 

[LarryFine]

It does not now nor has it ever said what ever the ohms reading is at that time is good enough.

Nor does it say the opposite. If your interpretation was the right one, it would say " ... one or more ... " and/or " ... until reaching 25 ohms."

In the NEC, not stating something is as indicative of intent as stating something is. What is not prohibited is considered as permissable.

 

[Bulldog1401]

If you want the exercise, drive as many as you want, the rest will drive the code required two and go home.

Roger

Some here seem to be hung up on the number of electrodes, not their quality. If this is so, then why not four 4 foot rods instead. Still 16 linear feet of rod.

The goal is not the number. It is not the number so that people dont try to drive an excesive number of rods until they get it down to 25 ohms. It is so that the rods you do drive are good ones. Which is the same reason you dont cut them down. Right back where we started. Thank you for putting the effort into trying to correct me on this. It shows that you are true professionals and care about the shape that the trade is taking as it progresses.

Unfourtunately, I, and others, don't agree with your interpetationof the code . I have challenged you to find your exact supporting verbage in the code and as of this point you have not. Which means you are standing on an interpetation, not a fact. It does not matter if the majority carries the same interpetation or not. Facts count, and it is a fact that 25 OHMs is spelled out in the code. No disrespect intended.

Thanks again.

 

[don_resqcapt19]

bulldog,

The code says 25 OHMS. It then says that a water pipe ground shall be supplimented by another electrode. If that does not measure 25 ohms, then you must drive one more rod. It does not now nor has it ever said what ever the ohms reading is at that time is good enough.

It does not say that in so many words, but it does say that.

250.56 Resistance of Rod, Pipe, and Plate Electrodes
A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode of any of the types specified by 250.52(A)(2) through (A)(7). Where multiple rod, pipe, or plate electrodes are installed to meet the requirements of this section, they shall not be less than 1.8 m (6 ft) apart.

Don

 

[roger]

OK Bulldog, I'll admit that driving a bunch of rods will accomplish a few things i.e.

#1 It will lighten your wallet

#2 If your driving them by hand it will build big arms and strong shoulders.

#3 It will help hand / eye coordination

#4 If you have some fellow employees driving the other rods at the same time as you and you can get a rhythm going, you can learn to sing songs like "I've been working on the railroad" or "Nobody knows the trouble I've seen"

#5 It will build character.

Of course, if you are using an electric or pneumatic hammer 2,3,4,&5 can be ignored.

Anyways, if you are dead set in reading what you want the code to say, I don't think anyone can help you keep that green in your wallet.

For fun, why not start a poll to see how many see it as you do?

BTW, this was in fun so don't get all mad or huffy, but really, start a poll or if you want me to I will. Let me know.

Roger

 

[stickboy1375]

The goal is not the number. It is not the number so that people dont try to drive an excesive number of rods until they get it down to 25 ohms. It is so that the rods you do drive are good ones.


Thanks again.

The way I read 250.56 is this, I drive a rod, I don't own any type of equipment to check the resistance, so I drive another rod, call it a day and go home to see the wife and kids, end of story... Look this thread did end with a happy ending...

 

[LarryFine]

have challenged you to find your exact supporting verbage in the code and as of this point you have not. Which means you are standing on an interpetation, not a fact. It does not matter if the majority carries the same interpetation or not. Facts count, and it is a fact that 25 OHMs is spelled out in the code.

So are 200 amps, 360 degrees, 480 volts, and 50 feet. But they only apply where they apply. You can't merely see a figure or value, such as 25 ohms, and say that it applies blindly to everything in the same paragraph, or even article.

Accept your challenge back, and show us where, in "exact verbage" it says that, if you cannot acheive 25 ohms with a single rod, then you must continue to add them until 25 ohms has been reached. Without requiring "interpretation."