Grounding Electrode Tap Conductors

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R Bob

Senior Member
Location
Chantilly, VA
250.64(D)/2002 permits tap conductors.
For what reason would the "TAP" not be allowed in the service disconnect enclosure?

Scenario:

400A service composed of 2-200A MB panels, each fed by #4/0AL SEU from meter base.
GEC #1/0AL, TAP conductors #2AL sized per 250.66 Note#1.

Why can't the #1/0AL GEC be run and terminated to the ground/neutral bar of one panel and the #2AL TAP conductor terminated on the same ground/neutral bar and be routed to and terminated at the other panel?

OR

Same scenario, except both panels have a PVC nipple between them.

Why can't GEC be routed into one panel and connected to the TAP conductors with a split bolt (as would be done on the outside of the panel) connector. The TAP conductors would then be routed and terminated at the ground/neutral bar of each respective panel. One would travel through the nipple to the other panel.

I usually make the TAP to the GEC on the outside of the panel and route the TAP conductors to each enclosure as specified in the Code Section.
This becomes a problem when the panels are flush with the finnished surface as the TAP must be accessable.

Just contemplating other options.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
R Bob said:
Scenario:

400A service composed of 2-200A MB panels, each fed by #4/0AL SEU from meter base.
GEC #1/0AL, TAP conductors #2AL sized per 250.66 Note#1.

Why can't the #1/0AL GEC be run and terminated to the ground/neutral bar of one panel and the #2AL TAP conductor terminated on the same ground/neutral bar and be routed to and terminated at the other panel?


Sounds good to me.
 

benaround

Senior Member
Location
Arizona
The GEC from the second panel is not continous if done in that mannor.

If you tap off the GEC to each panel, then the GEC is continous. jmo.
 

R Bob

Senior Member
Location
Chantilly, VA
infinity said:
Sounds good to me.

Sounds good to me too, but the tap is actually made inside of the enclosure via the neutral bar. Or is it considered a tap in this situation?

Even Mike Holt points out that the tap can't be made in the enclosure.:-?
 

R Bob

Senior Member
Location
Chantilly, VA
benaround said:
The GEC from the second panel is not continous if done in that mannor.

If you tap off the GEC to each panel, then the GEC is continous. jmo.

You may be right...I just can't comprehend it yet!
 

RUWired

Senior Member
Location
Pa.
The article states that if a connector listed as grounding and bonding is used, it can be made.It does'nt say where it has to be made.

The tap conductors shall be connected to the common grounding electrode conductor by exothermic welding or with connectors listed as grounding and bonding equipment in such a manner that the common grounding electrode conductor remains without a splice or joint.

Rick
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
The #1/0 would be the GEC the #2 would be a bonding jumper. Only the GEC is required to be continuous.
 

R Bob

Senior Member
Location
Chantilly, VA
infinity said:
The #1/0 would be the GEC the #2 would be a bonding jumper. Only the GEC is required to be continuous.

That's why I use a bug(split bolt).
Never had a problem with an EI.
Never had to CadWeld/HyPress a tap conductor.
(never say never:smile: )
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
R Bob said:
That's why I use a bug(split bolt).
Never had a problem with an EI.
Never had to CadWeld/HyPress a tap conductor.
(never say never:smile: )

Yup, a split bolt is code compliant.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
fireryan said:
are inspector makes use a irreversible clamp like a wr crimp or exothermic welding


He needs to read 250.64(D)(1). It says that you may use listed connectors.
 

benaround

Senior Member
Location
Arizona
infinity said:
The #1/0 would be the GEC the #2 would be a bonding jumper. Only the GEC is required to be continuous.

Rob, IMO the second panel does not need a bonding jumper, it needs a GEC.

250.64(D) 2005 describes this situation, permits us to connect taps,to the

'common' GEC. Without typing the whole thing, every sentence in it says one

common GEC, with two taps going to two enclosures. Is there a ref. you can

point out to me to see it the other way ?

:)
 

dnem

Senior Member
Location
Ohio
I haven't researched the new wording in 250.64(D) enough to be confident that I fully understand it. . But I do have an opinion based on what I see and what I've heard so far.

250.64(D) is multiple disconnects so all options are based on that.

When you connect to an electrode with as many electrode conductors as you have main disconnects, you have 250.64(D)(2).
When you connect to an electrode with only one single electrode conductor and take it to a common point for the neutral [such as a trough], you have 250.64(D)([/b]3[/b]).
When you connect to an electrode with only one single electrode conductor and take it to a tap point, you have 250.64(D)([/b]1[/b]).

For the two disconnect application specified on this thread, you connect to an electrode with only one single electrode conductor and take it to a tap point. . If that "tap" is located on the grounding/neutral bar of one panel, that conductor would be the common grounding electrode conductor that "remains without splice or joint". . The electrode conductor between the 2 panels would not be the common gec and so is not restricted to be without splice or joint. . It could be connected to the common gec on a main disconnect grounding/neutral bar, all of which are, by definition, "listed as grounding and bonding equipment".
BUT
If you have a third main disconnect and you "daisy chain" the third from the second, then the gec between the first and second is part of the common gec and the splice in the first disconnect would be a violation.

So for six main disconnects you would have to supply individual gecs all coming from the first main disconnect grounding/neutral bar. . You could not "daisy chain" from one grounding/neutral bar to the next:
1 to 2,
2 to 3,
3 to 4,
4 to 5,
5 to 6, according to the last sentence of 250.64(D)(1).

The one "blip" in this interpretation is that 250.64(D)(1) says, "A tap conductor shall extend to the inside of each service disconnecting means enclosure." . Does that wording require that the tap be located outside of the service disconnecting enclosure ?

Is this how any others here see the wording ?
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
Why even bother running a tap or anything else to the second panel? You are permitted to run the GEC from the grounded conductor upstream of the panels (this is typically done in a gutter common to both panels), and you'd use a GEC sized via 250.66 for the whole service for this. NEC 250.142(A) permits the grounded conductor to ground each panelboard as long as it is sized per 250.66. NEC 250.64(D)(3) also allows this.

I don't see how anything changes should you choose to run the GEC from one panel instead of a common gutter. The grey area is what is considered the "supply side of the service disconnecting means". Can a panelboard be that, as it contains both supply and load sides. You also must run a grounded conductor to each panelboard that is sized per 250.66 FOR THE WHOLE SERVICE and not just that panel.

The tap method seems most useful when you have multiple panels and there is a large disparity between their amp ratings. You may not want to run a neutral sized per the whole service 250.66 to a small 100A panelboard that is part of a 600A service. But with a dual 200A panel setup, most people run neutrals that are at least 1/0 copper to each panel.
 

dnem

Senior Member
Location
Ohio
infinity said:
The #1/0 would be the GEC the #2 would be a bonding jumper. Only the GEC is required to be continuous.

Only a common GEC is required to be continuous "without splice or joint". . If you run individual GECs to each main disconnect, you can splice the run according to 250.64(C)(1).

infinity said:
Yup, a split bolt is code compliant.

It's use is very restricted in a common GEC and tap GEC setup.
It can't be used at all in an individual GEC setup.

A split bolt is code compliant only for the tap connection between common GEC and the tap GECs. . Common GECs have to be "without splice or joint" and individual GECs can be spliced only by irreversible connectors or welding.

fireryan said:
are inspector makes use a irreversible clamp like a wr crimp or exothermic welding

Are you talking about a single individual GEC or a mulitple GEC taps off a common GEC ?

Let's say you had a tap situation:
Common
If you didn't have any one single piece of conductor long enough to go from the watermain to the spot that the taps will be attached, you can't splice that common GEC by any means: splitbolt, irreversible connector, or welding are all no good [250.64(D)(1)].
Tap
Your tap connection itself could be any of those three options: splitbolt, irreversible connector, or welding [250.64(D)(1)].
Individual
If you didn't have any one single piece of conductor long enough to go from the spot that the taps will be attached to one of the main disconnects, you can splice that individual GEC only by irreversible connector or welding and not by splitbolt [250.64(C)(1)].
 

R Bob

Senior Member
Location
Chantilly, VA
dnem said:
The one "blip" in this interpretation is that 250.64(D)(1) says, "A tap conductor shall extend to the inside of each service disconnecting means enclosure." . Does that wording require that the tap be located outside of the service disconnecting enclosure ?

Is this how any others here see the wording ?

Thanks for addressing this. It's the source of my OP.

The wording seems to imply that the tap conductor needs to originate outside of the enclosure that houses the service disconnecting means.

That means[my interpretation] that it would be a violation to connect the GEC to the grounding/neutral bar in one panel and extend a tap conductor to another panel as I have seen done.

It appears that the tap can be made without an enclosure or in an enclosue other than the enclosure for the service disconnecting means.

Mike Holt apparently reads it the same way we do. If you take a look at his publication, Understanding the Natinal Electrical Code 2002, Volume 1, page 179,where he addresses 250.64(D), he specifically says that the GEC Tap shall not take place within the service disconnect enclosure. Figure 250-119 on page 180 illustrates this by showing the tap external to the service disconnect enclosure and shows a split bolt used to make one of the taps to boot.

Any idea what the rationale is?
 

M. D.

Senior Member
Does this help at all??

http://www.mikeholt.com/onlinetraining/page_images/1113920864_6.jpg




Mike Holt EC&M

Taps. When a service consists of multiple disconnecting means as permitted in 230.71(A), you can use a grounding electrode tap from each disconnect to a common GEC [250.64(D)]. You must size the grounding electrode tap from each disconnect to the largest ungrounded conductor serving that disconnect per 250.66.


Fig. 3. Sizing the grounding electrode conductor for multiple connections can be a little tricky. Just remember to size it based on the service conductors feeding all disconnects.
Size the common GEC for the grounding electrode taps per 250.66. However, take note that you must base its size on the service conductors that feed all the service disconnects (Fig. 3).

Each grounding electrode tap must terminate to the common GEC in such a manner that the common GEC will be free of splices and joints. In addition, the grounding electrode tap can't be made within the service-disconnect enclosure.

Enclosures. Each end of ferrous (iron/steel) raceways, boxes, and enclosures that contain the GECs must be bonded to the GEC [250.92(A)(3)]. On the other hand, nonferrous metal raceways, such as aluminum RMC that enclose the GEC, don't need to be bonded to the GEC.
 
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M. D.

Senior Member
R Bob said:
It does help!
Thanks for the link and text quote.
I don't know how to do that yet.

you are welcome... to paste a link or bit of article highlight the stuff you want the go to the edit button at the top of page and click on copy then come here , go back to the edit button and click paste,..for a link highlight all that crap in the address bar and the rest is the same .. play around,.. you won't blow the thing up ,..at least I think you won't,.. good luck
 
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