ground rods

[roger]

Re: ground rods

Romeo, I must say I missed this

So it is important that if a ground rod is used to supplement
the water pipe it must meet the 25 ohm requirement or a second ground rod must be used,

part of your first post.

Sorry.

Roger

[ July 19, 2005, 10:44 AM: Message edited by: roger ]

 

[macmikeman]

Re: ground rods

Ya know, it's funny. The main function of the grounding electrode system is for lightning protection. The NFPA 780 (lightning protection) says to drive two 10 foot ground rods and call it a day. Why do we have to have ufer's and water pipes and building steel and ground rods and everything else?

Reply: Gives the vast majority of inspectors something to ping when they visit the jobsite.

 

[romeo]

Re: ground rods

Roger Not a problem.

romeo

 

[allenwayne]

Re: ground rods

Originally posted by augie47:
Gosh! Such confusion. You would think someone would come up with a national Code

Well the N in national sounds like that should encompass all of the U.S.A.
I have come to the cunclusion WHAT ARE THE RULES TODAY

 

[charlie]

Re: ground rods

Romeo, I did the same thing as Roger. Read his post and pretend I said the same thing.

Sorry,
Charlie

 

[rick hart]

Re: ground rods

Ya know, it's funny. The main function of the grounding electrode system is for lightning protection. The NFPA 780 (lightning protection) says to drive two 10 foot ground rods and call it a day. Why do we have to have ufer's and water pipes and building steel and ground

First time I've tried quoting hope it works....

Grounding a service? Or grounding a lightning system? These are separate systems that are bonded together but do different things.
IMO the service grounding is to insure the ground fault protection operates, the mid point is referenced and will not float around depending on the loading of other phases AND to give the inspectors something to carp about.

Or did I not completely understand the comment?

To use the quote, the quoted section must be between the ['QUOTE] and the ['/QUOTE] (I added a hyphen in each to kill the function). Take care, Charlie

[ July 19, 2005, 03:33 PM: Message edited by: charlie ]

 

[infinity]

Re: ground rods

Actually, New York State requires that you also use #4 solid copper to hook up the ground wires

New York State does not have a unified electrical code. I don't think that your statement is true for every county in New York.

 

[romeo]

Re: ground rods

Charlie I will say the same thing to you as I said to Roger NOT A PROBLEM This is a great forum because there is always someone here to correct us. That is why I am here I make a lot of mistakes and I am always ready to learn even at 70 years old. Thanks

romeo

 

[iwire]

Re: ground rods

Originally posted by rick hart:
Grounding a service? Or grounding a lightning system? These are separate systems that are bonded together but do different things.
IMO the service grounding is to insure the ground fault protection operates, the mid point is referenced and will not float around depending on the loading of other phases AND to give the inspectors something to carp about.

The thing is a grounding electrode system can not cause an OCPD in the building to operate.

The grounding electrode system can only 'encourage' the midpoint not to float.

In other words if there is a big enough push the GES will indeed by at a potential higher than the earth.

[ July 19, 2005, 05:08 PM: Message edited by: iwire ]

 

[george t. everett]

Re: ground rods

mc5w,
Where do you find this requirement in New York State? All POCO's have different requirements, this has nothing to do with New York State.

 

[LarryFine]

Re: ground rods

I have another theory about grounding electrodes:

The help keep the earth around electrical equipment at the same potential as the equipment, whether or not at 0 volts. In other words, to minimize voltage gradients, like the equipotential pool grid.

 

[iwire]

Re: ground rods

Originally posted by LarryFine:
I have another theory about grounding electrodes:

The help keep the earth around electrical equipment at the same potential as the equipment, whether or not at 0 volts. In other words, to minimize voltage gradients, like the equipotential pool grid.

The pool grid works because it uses copper conductors to bond everything together. The whole grid could have a potential between it and the earth but not between bonded metal parts.

Imagine taking a ground rod and sinking it in the ground, now apply 120 volts to it. Nothing happens.

Now if you where standing on the ground just a couple of feet away from this rod and reached over and touched the top of the rod you would get blasted.

 

[hurk27]

Re: ground rods

By Allen: gfci sticker missed

Allen
Are you saying they require GFCI stickers on new construction?

What code are they citing on that one???

 

[LarryFine]

Re: ground rods

Originally posted by iwire:
Now if you where standing on the ground just a couple of feet away from this rod and reached over and touched the top of the rod you would get blasted.

Okay. Now imagine the same scenario, but without the rod; just grab a live conductor.

Bigger blast.

 

[iwire]

Re: ground rods

Originally posted by LarryFine:

Originally posted by iwire:
Now if you where standing on the ground just a couple of feet away from this rod and reached over and touched the top of the rod you would get blasted.

Okay. Now imagine the same scenario, but without the rod; just grab a live conductor.

Bigger blast.

Actually almost no difference at all and the effectiveness diminishes rapidly as you move away from the rod.

 

[stevenj]

Re: ground rods

The NEC does allow for plumbing lines to be used as a ground rod if 3 conditions are met.
1. A ground rod system is also present. (two ground rods minimum)
2.the pipe is in contact with a least 10 feet of earth ( impossible to tell)
3. The connection to the pipe is a least 5 ft of where the pipe enters the building.

Think of it this way. If in the future a plumber replaces a metal pipe with pvc plastic he will nullify the ground system.

The copper plumbing system should be thought of as something that needs to be grounded , not something to ground to.

 

[hurk27]

Re: ground rods

By Steven J: The NEC does allow for plumbing lines to be used as a ground rod if 3 conditions are met.

Steve the NEC "requires" that we use the water pipe.(250.50) It's not an allowance. It only "requires this if 10' or more are in direct contact with earth.
Now if we are required to use the water pipe (meaning it meets the above) It must be connected within 5' of where it enters the building, we must install or connect to an additional grounding electrode(250.53(D)(2) listed in 250.52(A)(2) to (A)(7). This is not a permissive rule it is a requirement.

Or did ya just get ya wording wrong?

1. A ground rod system is also present. (two ground rods minimum)

Thats not what the NEC Say's? (see bold)
It only requires a second rod if the first one does not meet the 25 ohm requirement.
See 250.56

[ July 20, 2005, 01:58 AM: Message edited by: hurk27 ]

 

[stevenj]

Re: ground rods

My wording is wrong here. I wrote this to fast.
I though it was.. and it is. I should have double checked this. thanks for the heads up.

 

[stevenj]

Re: ground rods

If I did my job like I write , I would fail Inspection everytime haha..

 

[macmikeman]

Re: ground rods

here we go again. 250.52 requires connection to be no more than 5 ft from where the buried pipe in (direct contact with the soil for more than 10 ft.) enters the building if it is INTERIOR. If you connect on the exterior of the building it can be anywhere on the pipe.