Explained 250.64

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Eddy Current

Senior Member
Can someone explain this in layman's terms?


"Where a service consists of of more than a single enclosure it is permissible to connect taps to the GEC, provided each tap extends all the way into the inside of each enclosure. The tap conductors shall be connected to the GEC in such a manner that the GEC remains without a splice."
 

kwired

Electron manager
Location
NE Nebraska
Can someone explain this in layman's terms?


"Where a service consists of of more than a single enclosure it is permissible to connect taps to the GEC, provided each tap extends all the way into the inside of each enclosure. The tap conductors shall be connected to the GEC in such a manner that the GEC remains without a splice."

Which part of it are you having trouble with? A service can have up to six disconnecting means, or more with some exceptions. You only need a single GEC but it needs bonded to each service enclosure. One common practice is to run the GEC to one service enclosure unspliced and bond the others to the GEC via tap devices that do not require cutting the GEC to attach them.
 

infinity

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Here's an example from the NECH where the GEC is unbroken. Taps can be connected with split-bolts since only the GEC is required to be spliced by irreversible means.

250.66+Taps.JPG
 

Eddy Current

Senior Member
It didn't say "tap without a splice" it said the GEC was to "remain without a splice".

Look at the picture that infinity posted. The GEC is continuous and the bonds to the other enclosures are tapped to the GEC.


I was talking about the Code reference i posted in the first post, i didn't really understand what they meant by tap without a splice.
 

jusme123

Senior Member
Location
NY
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JW
...you can't cut the GEC at the first disconnect and splice it to reach the second disconnect, it has to be continuous (without splice). Thats why the pic shows the GEC going from the ground, strait past the first disc and ends at the second disc. Than wires are run from each disc and tapped to the GEC, as shown in pic.
 

Little Bill

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I was talking about the Code reference i posted in the first post, i didn't really understand what they meant by tap without a splice.

I was quoting exactly what you posted in your OP. It doesn't say "tap without a splice"

Here is what you quoted in your OP...notice it doesn't say "tap without a splice".

"Where a service consists of of more than a single enclosure it is permissible to connect taps to the GEC, provided each tap extends all the way into the inside of each enclosure. The tap conductors shall be connected to the GEC in such a manner that the GEC remains without a splice."

But here is the text straight from the code 250.64(D)(1)(2)

I highlighted in red what you need to see. Again it doesn't say anything about taps without a splice.
(1) Grounding Electrode Conductor Taps. Where the
service is installed as permitted by 230.40, Exception No.
2, a common grounding electrode conductor and grounding
electrode conductor taps shall be installed. The common
grounding electrode conductor shall be sized in accordance
with 250.66, based on the sum of the circular mil area of
the largest ungrounded service-entrance conductor(s).
Where the service-entrance conductors connect directly to a
service drop or service lateral, the common grounding electrode
conductor shall be sized in accordance with Table
250.66, Note 1. A tap conductor shall extend to the inside
of each service disconnecting means enclosure. The
grounding electrode conductor taps shall be sized in accordance
with 250.66 for the largest conductor serving the
individual enclosure. 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.
 
Last edited:

kwired

Electron manager
Location
NE Nebraska
Here's an example from the NECH where the GEC is unbroken. Taps can be connected with split-bolts since only the GEC is required to be spliced by irreversible means.

250.66+Taps.JPG

I know you know this, but I want to mention for clarification for others, particular Eddy Current.

It is common for the installation in the picture to have the 2 AWG GEC run from the electrode unbroken all the way to the disconnect on the right with a tap to the disconnect on the left. This saves one splicing device, but it is likely drawn the way it is to show that it is ok to make taps to each disconnect also.
 

infinity

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It is common for the installation in the picture to have the 2 AWG GEC run from the electrode unbroken all the way to the disconnect on the right with a tap to the disconnect on the left. This saves one splicing device, but it is likely drawn the way it is to show that it is ok to make taps to each disconnect also.

I agree. And what do you think about this, instead of the #4 tap condcutor to the switch to the right they used a #2, would the connection need to be irreversible?
 

kwired

Electron manager
Location
NE Nebraska
I agree. And what do you think about this, instead of the #4 tap condcutor to the switch to the right they used a #2, would the connection need to be irreversible?
Not really sure. I can tell you if I were arranging things exactly as shown in that example I would have run the GEC to the gutter on top and connected directly to the service neutral, instead of to each disconnect.
 

Little Bill

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Tennessee NEC:2017
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I agree. And what do you think about this, instead of the #4 tap condcutor to the switch to the right they used a #2, would the connection need to be irreversible?

No it wouldn't. The keyword here is tap and the tap is not required to be an irreversible connection.

Also, kwire mentioned that it would be most common to run the GEC unbroken to one of the panels with the other panel having the tap. I also agree, but there could also be another panel (not shown) downstream in the picture since it appears the GEC continues.
 

Little Bill

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Tennessee NEC:2017
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No it wouldn't. The keyword here is tap and the tap is not required to be an irreversible connection.

Also, kwire mentioned that it would be most common to run the GEC unbroken to one of the panels with the other panel having the tap. I also agree, but there could also be another panel (not shown) downstream in the picture since it appears the GEC continues.

I think it is just drawn that way to indicate a little more clearly that there is two different conductors involved there.

Probably so. That's why I said "could" be another panel.:p
 

infinity

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New Jersey
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I agree. And what do you think about this, instead of the #4 tap condcutor to the switch to the right they used a #2, would the connection need to be irreversible?

No it wouldn't. The keyword here is tap and the tap is not required to be an irreversible connection.

If the tap is the same size as the GEC is it really a tap or is it splicing of the GEC which would require an irreversible connection.
 

Little Bill

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Tennessee NEC:2017
Occupation
Semi-Retired Electrician
If the tap is the same size as the GEC is it really a tap or is it splicing of the GEC which would require an irreversible connection.

If the GEC was unboken and continued on, then it is still a tap. If it went no further than where the alidged tap is, then went to the panel, it would be a splice and would require an irreversible connection.
The way your drawing/image is shown, the GEC is continuous with the conductor to the panel tapped onto it. In that case it wouldn't matter the size of the conductor as long as it was the minimum size required.
 
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