Grounding Electrode System Fundamentals

[George Stolz]

A word to the casual reader: much of what follows may seem a bit disjointed - posts in this thread have been copied from a previously closed thread.

My purpose in going to all this trouble is that we have disagreement on the basics of grounding among some longtime members of the forum, and I feel it would behoove all of us to take a minute to collect ourselves, for the sake of accuracy.

 

[Smart $]

...cite the code section that would be violated by pulling a GEC to a ground rod, and then pulling a bonding jumper to the Ufer?

250.68(C).

There are only three locations where a bonding jumper can connect.... and none of them are a ground rod.

 

[roger]

Roger

 

[Dennis Alwon]

The ufer when connected thru the rod as you have done is not compliant as an electrode. The grounding electrode conductor must be #4 and connected directly to the ufer conductor not thru the rod.IMO

 

[George Stolz]

250.68(C).

There are only three locations where a bonding jumper can connect.... and none of them are a ground rod.

Bonding jumpers can connect grounding electrodes themselves, 250.68(C) is covering items that are not grounding electrodes. A ground rod is a grounding electrode. See 250.64(F)(1).

 

[George Stolz]

The ufer when connected thru the rod as you have done is not compliant as an electrode. The grounding electrode conductor must be #4 and connected directly to the ufer conductor not thru the rod.IMO

There is no prohibition from using a #6 CU to a ground rod terminating it in it's own acorn (as shown), and then connecting a #4 from a Ufer to the rod with it's own acorn. We have not heard the service size to see if the GEC is undersized in this configuration. In that case the Ufer is still fine connected to the ground rod, they just need to swap the #6 for #4.

 

[infinity]

There is no prohibition from using a #6 CU to a ground rod terminating it in it's own acorn (as shown), and then connecting a #4 from a Ufer to the rod with it's own acorn. We have not heard the service size to see if the GEC is undersized in this configuration. In that case the Ufer is still fine connected to the ground rod, they just need to swap the #6 for #4.

Also if the CEE is rebar and the GEC/bonding jumper is only required to be a #6 (like for a typical 100 amp service) you wouldn't need a #4 to the rebar.

 

[Smart $]

Bonding jumpers can connect grounding electrodes themselves, 250.68(C) is covering items that are not grounding electrodes. A ground rod is a grounding electrode. See 250.64(F)(1).

While 250.64(F)(1) and 250.68(C) are in separate sections, they are not separate requirements in the connection of grounding electrode conductors and bonding jumpers to electrodes.

Look carefully at the Mike Holt graphic posted by Roger. Name one [electrode] bonding jumper which is not connected to one of the three locations named in 250.68(C).

 

[Dennis Alwon]

There is no prohibition from using a #6 CU to a ground rod terminating it in it's own acorn (as shown), and then connecting a #4 from a Ufer to the rod with it's own acorn. We have not heard the service size to see if the GEC is undersized in this configuration. In that case the Ufer is still fine connected to the ground rod, they just need to swap the #6 for #4.

I agree it does not express the words exactly but if the rod is not equivalent to a #6 conductor I would infer a violation especially since we know that the rod may be only good for 20 years or so.

 

[Dennis Alwon]

Also if the CEE is rebar and the GEC/bonding jumper is only required to be a #6 (like for a typical 100 amp service) you wouldn't need a #4 to the rebar.

I disagree

(3) Concrete-Encased Electrode. A concrete-encased electrode
shall consist of at least 6.0 m (20 ft) of either (1) or (2):
(1) One or more bare or zinc galvanized or other electrically
conductive coated steel reinforcing bars or rods of
not less than 13 mm (1⁄2 in.) in diameter, installed in
one continuous 6.0 m (20 ft) length, or if in multiple
pieces connected together by the usual steel tie wires,
exothermic welding, welding, or other effective means
to create a 6.0 m (20 ft) or greater length; or
(2) Bare copper conductor not smaller than 4 AWG
Metallic components shall be encased by at least 50

 

[kwired]

Can you substantiate this "main electrode" concept you're putting forward, and cite the code section that would be violated by pulling a GEC to a ground rod, and then pulling a bonding jumper to the Ufer?

No, but I have always tried to run full sized (according to 250.66) and unspliced GEC directly to building steel or water pipe electrode first - because they always require full size. CEE doesn't need to be more then 4 AWG ever, conductor that is sole connection to a rod never needs to be larger then 6 AWG.

May not be in the wording of the code, but also doesn't quite make sense to run to the poorer elecrode then make a bonding jumper to a better one if they want no splices in the GEC.

What OP has may not be wrong but I typically try to avoid such a situation whenever possible. I'd rather see a GEC to the CEE then jumper to a rod (though the rod shouldn't be necessary anyway) then the GEC to the rod then jumper to CEE. But one also has to understand and consider the situation here and that it was damaged/tampered with and how to deal with it.

That is based on what I get out of code requirements, my own thoughts on what happens in real world and my understanding of electrical theory - what he has is sufficient, but his inspector is the one that has to give it the final blessing anyway, so that gives code the most weight as that is where any argument from either side will have for references.

OP also needs better protected conductor to help prevent copper theft. Photo of final install is still right in the open and easy to take, and is bright and shiny to capture attention.

 

[infinity]

Also if the CEE is rebar and the GEC/bonding jumper is only required to be a #6 (like for a typical 100 amp service) you wouldn't need a #4 to the rebar.

I disagree

I don't think that you read what I wrote correctly, according to the section you quoted the GEC is not required to be #4 if you have a CEE made of rebar.

 

[Dennis Alwon]

I don't think that you read what I wrote correctly, according to the section you quoted the GEC is not required to be #4 if you have a CEE made of rebar.

You are correct, my bad, but I cannot imagine running anything smaller to a concrete encased electrode especially if the connection is in the footing. Unuseable in an upgrade...

 

[George Stolz]

I have copied posts from a closed thread (DIY) for the purposes of discussing aspects of Article 250. I apologize in advance for any confusion this may present, but I figured this was the easiest way to collectively continue without violating the DIY policy.

 

[George Stolz]

250.68(C).

There are only three locations where a bonding jumper can connect.... and none of them are a ground rod.

While 250.64(F)(1) and 250.68(C) are in separate sections, they are not separate requirements in the connection of grounding electrode conductors and bonding jumpers to electrodes.

Look carefully at the Mike Holt graphic posted by Roger. Name one [electrode] bonding jumper which is not connected to one of the three locations named in 250.68(C).

Smart, the entire reason 250.68(C) was added to the code book was to introduce allowances for connecting GECs and GEBJs to items not listed in 250.52. Historically we have almost always connected to a metal water pipe outside of the defined area in 250.52(A)(1) - outside of earth. Mike's graphic is testament to that - it predates the new section. Recently CMP-5 has evolved a new way of looking at this, that connecting outside the specific definitions provided would be a code violation, if not for the new 250.68(C).

If you connect directly to the electrode - directly where described in 250.52, you do not need 250.68(C)'s allowances.

 

[George Stolz]

KWired, I understand where you are coming from - but the situation that prompted the "band-aid" in the DIY thread was explicitly about finding a code-compliant way around a problem, not a best practice for the first try. There were no splices in the GEC.

There are many non-compliant fixes that get employed, I try to advocate for the legal (and little bit tricky, educational) fixes when the opportunity presents.

 

[Smart $]

Smart, the entire reason 250.68(C) was added to the code book was to introduce allowances for connecting GECs and GEBJs to items not listed in 250.52. Historically we have almost always connected to a metal water pipe outside of the defined area in 250.52(A)(1) - outside of earth. Mike's graphic is testament to that - it predates the new section. Recently CMP-5 has evolved a new way of looking at this, that connecting outside the specific definitions provided would be a code violation, if not for the new 250.68(C).

If you connect directly to the electrode - directly where described in 250.52, you do not need 250.68(C)'s allowances.

Are you certain we are reading the same 250.68... and (C) thereunder?

250.68 Grounding Electrode Conductor and Bonding
Jumper Connection to Grounding Electrodes. The connection
of a grounding electrode conductor at the service, at
each building or structure where supplied by a feeder(s) or
branch circuit(s), or at a separately derived system and associated
bonding jumper(s) shall be made as specified 250.68(A)
through (C).

...

(C) Grounding Electrode Connections. Grounding electrode
conductors and bonding jumpers shall be permitted to
be connected at the following locations and used to extend
the connection to an electrode(s):

(1) Interior metal water piping located not more than 1.52 m
(5 ft) from the point of entrance to the building shall be
permitted to be used as a conductor to interconnect electrodes
that are part of the grounding electrode system.

Exception: In industrial, commercial, and institutional buildings
or structures, if conditions of maintenance and supervision
ensure that only qualified persons service the installation,
interior metal water piping located more than 1.52 m (5 ft)
from the point of entrance to the building shall be permitted as
a bonding conductor to interconnect electrodes that are part
of the grounding electrode system, or as a grounding electrode
conductor, if the entire length, other than short sections passing
perpendicularly through walls, floors, or ceilings, of the
interior metal water pipe that is being used for the conductor
is exposed.

(2) The metal structural frame of a building shall be permitted
to be used as a conductor to interconnect electrodes
that are part of the grounding electrode system,
or as a grounding electrode conductor.

(3) A concrete-encased electrode of either the conductor
type, reinforcing rod or bar installed in accordance with
250.52(A)(3) extended from its location within the concrete
to an accessible location above the concrete shall
be permitted.

Sure you can connect a grounding electrode conductor directly (i.e. from any location listed in 250.68 general statement) to any 250.52 electrode, but to connect a grounding electrode with a bonding jumper (electrode to electrode essentially), one end of the bonding jumper must connect at one of the three locations while the other end connects to the electrode.

 

[George Stolz]

Are you certain we are reading the same 250.68... and (C) thereunder?

I am now. You quoted the whole thing.

Sure you can connect a grounding electrode conductor directly (i.e. from any location listed in 250.68 general statement) to any 250.52 electrode, but to connect a grounding electrode with a bonding jumper (electrode to electrode essentially), one end of the bonding jumper must connect at one of the three locations while the other end connects to the electrode.

Not so; look at 250.53(C) and 250.64(F)(1). Bonding jumpers that directly connect electrodes - true electrodes, not their accessories - together do not give 250.68(C) a second glance. 250.68(C) only comes in when we have a near miss:

1. Connect to a water pipe outside of dirt, or
2. Connect to building steel that doesn't qualify as an electrode, or
3. Connect to a CEE outside of concrete.

 

[ActionDave]

Sure you can connect a grounding electrode conductor directly (i.e. from any location listed in 250.68 general statement) to any 250.52 electrode, but to connect a grounding electrode with a bonding jumper....

I think this is the nub of it. There is only one Grounding Electrode Conductor.

 

[Smart $]

...Not so; look at 250.53(C) and 250.64(F)(1). Bonding jumpers that directly connect electrodes - true electrodes, not their accessories - together do not give 250.68(C) a second glance. 250.68(C) only comes in when we have a near miss:

1. Connect to a water pipe outside of dirt, or
2. Connect to building steel that doesn't qualify as an electrode, or
3. Connect to a CEE outside of concrete.

I understand what you are saying and I'm not against it if that is the true intent... but nothing in the wording of 250.68 or (C) thereunder says exactly what you are saying. For example, nothing says metal water pipe entering a building which may of may not qualify as an electrode but it is the same location where a qualifying electrode connection is made, or building steel which does not qualify as an electrode, and CEE is referenced by word in (C)(3). IMO, there should be something in there that states what you are saying and there is not.

I do realize CMP's are stubborn when it comes to any proposal to make the wording explicit. The majority of times, what is clear in their heads is not clear on paper, but they'll insist that it is.