GEC to gd rods

[george t. everett]

In the EC mag (June 05) Q&A section, it was asked if the GEC to 2 gd rods has to be continuous. The answer was yes. In Mike Holt's Grounding versus Bonding , he shows a bonding jumper between rods. Am I missing something?

 

[roger]

Re: GEC to gd rods

Good morning George, magazines articles need to be taken lightly.

Many of these authors are simply voicing an opinion and if they had any sense at all, they would ask here before making a mistake in print as this author did. Of course the article may have to wait a few months to be published.

NOTE: The above was in fun

In all seriousness, the GEC only has to hit one point of the GES, after that the GES must only be bonded together and back to this first point where the GEC has landed.

Now, if we look at the wording where a second rod must be added if the first rod does not make the 25 ohm requirement, then the second rod can be interpreted as part of the GE (as in one) and I can see the reasoning of a continuous GEC to both. I don't think it's necessary though.


Roger

[ July 09, 2005, 09:10 AM: Message edited by: roger ]

 

[stud696981]

Re: GEC to gd rods

Roger is correct, it doesn't have to be one continuous piece of wire. However, since some inspectors misunderstand this section, I always make it one continuous lenght when installing ground rods just to avoid any debates.

 

[iwire]

Re: GEC to gd rods

Here is a picture from the 2002 Handbook that illustrates how the connections can be made.

 

[jwelectric]

Re: GEC to gd rods

At the risk of getting something started I think the word continuous needs to be looked at the way the NEC looks at it.

This grounding electrode conductor has been the debate for some time now with some people fighting to the end that if it is cut it WILL be replaced.

I would like to look at a comparison to this grounding electrode conductor being required to be continuous as the same requirement in the NEC that the equipment grounding conductor of an underwater light at a pool as outlined below.

2005, 680.23 (F)(2) The equipment grounding conductor shall be installed without joint or splice

2002, 680.23 (F)(2) The equipment grounding conductor shall be installed without joint or splice

1999, 680-25 (b)(4) The equipment grounding conductor shall be installed without joint or splice

Now that the sections are posted I ask if the equipment grounding conductor for a pool light is required to be continuous.

While this is given some thought let?s look at the diving board of this pool. Just under this board is a junction box. In this box is a termination of this equipment grounding conductor that is required to be with out joint or splice.

The connection of the grounding electrode conductor at a driven rod is the same as the equipment grounding conductor for this pool light. Both are continuous.

Another comparison I use is found in the 2002 and 2005 cycle in 250.52

(A)(1): electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe)

Would this not sound like 250.64 (C)? The one thing that is not listed in 250.64 (C) is terminations.

As is evidenced by many code cycles the termination of a conductor does not constitute a splice or joint and is considered to be continuous.

As pointed out above, some people (me included) inject a lot of opinion in their statements. Some have merit, other don?t.

 

[electricmanscott]

Re: GEC to gd rods

Originally posted by roger:
if they had any sense at all, they would ask here before making a mistake in print as this author did.

Are you sure about that.

 

[infinity]

Re: GEC to gd rods

The illustration posted by Bob shows more than one grounding electrode. The question in EC&M was about only using two ground rods as the grounding electrode. If two rods together make one grounding electrode I don't see how the GEC could be installed and not be unbroken as in 680.23(A)(2). It should be continuous from the service and from one rod to the other.

 

[iwire]

Re: GEC to gd rods

And here I thought this was cut and dry. :roll:

 

[iwire]

Re: GEC to gd rods

Originally posted by infinity:
The question in EC&M was about only using two ground rods as the grounding electrode. If two rods together make one grounding electrode I don't see how the GEC could be installed and not be unbroken as in 680.23(A)(2). It should be continuous from the service and from one rod to the other.

I strongly disagree that it must be continuous.

Where is it said when we tie two rods together we have one grounding electrode. Notice 250.56 states "single electrode" and goes on to state " one additional electrode" nowhere does it state 'connected together to make one electrode'.

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.

It is two electrodes 250.52(A)(5) bonded together into a grounding electrode system 250.50 with a bonding jumper installed per 250.53(C).

[ July 09, 2005, 02:05 PM: Message edited by: iwire ]

 

[peter d]

Re: GEC to gd rods

My own take on this is that the second rod is purely supplemental, therefore the GEC is not required to be continuous from the first rod to the second. But try telling that to an inspector who has required it that way for his whole career. :roll:

 

[infinity]

Re: GEC to gd rods

Where is it said when we tie two rods together we have one grounding electrode. Notice 250.56 states "single electrode" and goes on to state " one additional electrode" nowhere does it state 'connected together to make one electrode'.

Bob,

I see your point. The NEC doesn't define the two grounds rods together as "one electrode" so I'd guess that it's not enforceable to say that they are. As it's been said before if the code doesn't say that you can't, then you can.

 

[LarryFine]

Re: GEC to gd rods

It may be that the typical rod clamp (aka "acorn clamp") is designed for only a single wire, so an unbroken wire is the only way a single clamp can be used on each rod.

We recently had to reconnect a rod because my employee bent the single wire into a U before inserting into the clamp. The remark was "clamp designed for a single wire", and the AHJ considered the doubled wire as two.

 

[iwire]

Re: GEC to gd rods

Originally posted by LarryFine:
It may be that the typical rod clamp (aka "acorn clamp") is designed for only a single wire, so an unbroken wire is the only way a single clamp can be used on each rod.

Thats fine.....use two clamps.

 

[tom baker]

Re: GEC to gd rods

The GEC to ground rods can be
one wire, two clamps
two wires, three clamps

George had it correct in the second post. the GEC runs to the first grnd electrode, all other electrodes are connected via bonding jumpers

 

[George Stolz]

Re: GEC to gd rods

Originally posted by tom baker:
George had it correct in the second post.

I'm so good, I don't even have to chime in to get credit.

 

[roger]

Re: GEC to gd rods

George, you would have said the same thing.

Roger

 

[grandpapastu]

Re: GEC to gd rods

What technical or mechanical reason would anyone have for not wanting to install the GEC in one continuous length from the main service point to both ground rods?
IAEI Soares' book:
'Resistance of current through an earth electrode actually has three components as shown in Figure 6-10:
1. Resistance of the electrode itself and connections to it.
2. Contact resistance between the electrode and the soil adjacent to it.
3. Resistance of the surrounding earth.'

To break the GEC at the first rod and then bond the first rod to the second rod with an additional segment of wire would neccesarily require the 1. Resistance of the electrode (2nd rod) and connections to it to depend on an additional mechanical connection and added contact resistance.
Back to basics:
the least amount of splices and junctions in my system the better.
86 as for practical to sound electric design any and all unnecessary taps and splices to minimize the potential of electrical/mechanical failure.

 

[charlie]

Re: GEC to gd rods

grandpapastu, you are now talking about design issues. The Code is a set of minimum standards, you may exceed those standards anytime you wish.

 

[grandpapastu]

Re: GEC to gd rods

Oh, I agree, and it only makes sense to me that all my work should meet and exceed NEC requirements.
I understand that the original post was a code question.
I have learned that many code questions are answered with good basic electric design sense though.
With an understanding of basic electric design the NEC is better understood. No offense meant to anyone of course. Exercise is good!
Sometimes I just have to ask 'why ask why if,'.

 

[hurk27]

Re: GEC to gd rods

I think all this confusion goes back to people thinking that grounding electrode (rod type) are there to pass huge amounts of current back to planet Earth. When in realty a rod type grounding electrode can't even over load a 20awg wire at the NEC minimum of 25 ohms if 120 volts was applied to it. There are many of these myths still built into the NEC that have been there for many years that should be removed. We can splice conductors with over 4,000 amps on them but we can't splice a grounding electrode conductor that might get 10 amps on it? And that would be with half of the NEC required resistance.