Combo GEC and EGC

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Gordon Stevenson

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Scenario: 200 amp service and disconnect on exterior with distribution panel back to back with service. #4 solid copper run from service neutral buss to ground rod directly below and a second #4 solid copper run with the feeder conductors into distribution panel through lug on panel ground buss and continuing unbroken out of panel over to water main entrance to pipe clamp. Can this serve both purposes as GEC and EGC?
 
The section of that #4 conductor from outdoor disco to indoor MDP is the EGC. The section of that #4 from the indoor MDP to the water line is the GEC, even if it is an unbroken conductor. . That basically makes the GEC to the water line originate at the indoor subpanel and not at the outdoor service disconnect, as it should. That's my take on it, anyhow. If it's legal, it's clever.
 
Here's another "take":

The disco to the ground rod #4 is "the" GEC.

The #4 from the disco -- thru the subpanel -- to the water pipe is a grounding electrode jumper.

So ... 1) can a grounding electrode jumper also serve as the EGC ... and, 2) can it pass thru the distro subpanel enroute ... ???

(I'm still looking it up myself)
 
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The neutrals and EGC's in the interior panel are isolated, right? This #4 should not be in contact with the neutral bus inside.

By the way, you could have had the main inside, and the neutrals and grounds need not have been isolated. The service neutral could have done double duty, and you wouldn't have needed the #4 to run from meter to panel.
 
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LarryFine said:
The neutrals and EGC's in the interior panel are isolated, right? This #4 should not be in contact with the neutral bus inside.
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Good you asked to make sure!

I just assumed that the inside distro panel was indeed configured as a sub-panel.
 
NoVA Comms Power said:
So ... 1) can a grounding electrode jumper also serve as the EGC ... and, 2) can it pass thru the distro subpanel enroute ... ???
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1. I say that the neutral bus in the exterior disconnect is the bonding jumper, and the #4 passing into the panel is the service EGC to the grounding bus, and the water bond/GEC (which one depending on the usual requirements: 5' of entrance, 10' continuous in contact with earth).

2. I see no reason why not.
 
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NoVA Comms Power said:
See Table 250.66 for GEC sizing. (it varies w/ the size/material of the service conductors)

#6 is sufficient for grounding electode jumpers.
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That is my point. He is running #4 to the ground rod when a #6 is sufficient.
 
Nova, actually #6 CU is good for a ground rod for any size service, see 250.66(A)

We wouldn't need to use the Table for this.

(A) Connections to Rod, Pipe, or Plate Electrodes Where the grounding electrode conductor is connected to rod, pipe, or plate electrodes as permitted in 250.52(A)(5) or (A)(6), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.
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Roger
 
Gordon Stevenson said:
#4 solid copper run with the feeder conductors into distribution panel through lug on panel ground buss and continuing unbroken out of panel over to water main entrance to pipe clamp. Can this serve both purposes as GEC and EGC?
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I take ground buss to be the equipment ground bus that is electrically separate from the neutral in the distribution panel.

The key is that the #4 conductor is unbroken. Because of that, the #4 conductor is, for its entire length, the GEC.

The distribution panel lug on the EGC bus in the distribution panel connects the panel EGC to the GEC.

Makes sense to me.:)
 
al hildenbrand said:
I take ground buss to be the equipment ground bus that is electrically separate from the neutral in the distribution panel.

The key is that the #4 conductor is unbroken. Because of that, the #4 conductor is, for its entire length, the GEC.

The distribution panel lug on the EGC bus in the distribution panel connects the panel EGC to the GEC.

Makes sense to me.:)
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What would it be if, in a typical main breaker panel, the #4 goes from the neutral/ground terminal in the service panel, to an existing grounding electrode (an underground boiler pipe about 30 ft long; not the water system pipe or ground rod) and then on to the copper water supply pipe, without a break at the first grounding electrode?

The #4 GEC hits both grounding electrodes that exist in the building. Is it a GEC all the way, or does it become an EGC part of the way?
 
Isn't there something in the code (I am looking for it) that will not allow a solid wire in a conduit if it is larger than #10. Art 310.3--
 
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NoVA Comms Power said:
See Table 250.66 for GEC sizing. (it varies w/ the size/material of the service conductors)

#6 is sufficient for grounding electode jumpers.
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Regardless of what you call the conductor going to a ground rod it never has to be larger than #6 if not subject to damage.
 
I am going to try again. The original post says:

Gordon Stevenson said:
Scenario: 200 amp service and disconnect on exterior with distribution panel back to back with service. #4 solid copper run from service neutral buss to ground rod directly below and a second #4 solid copper run with the feeder conductors into distribution panel through lug on panel ground buss and continuing unbroken out of panel over to water main entrance to pipe clamp. Can this serve both purposes as GEC and EGC?
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I am assuming there is a conduit connecting the service disconnect to the sub panel with a #4 solid copper running through the pipe along with the feeder conductors. This is a violation of Article. 310.3. I believe the exception "as permitted elsewhere in the code" refers to sleeving the GEC to protect it from damage.

Please correct me if I am wrong.
 
Dennis Alwon said:
I am going to try again. The original post says:



I am assuming there is a conduit connecting the service disconnect to the sub panel with a #4 solid copper running through the pipe along with the feeder conductors. This is a violation of Article. 310.3. I believe the exception "as permitted elsewhere in the code" refers to sleeving the GEC to protect it from damage.

Please correct me if I am wrong.
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You are correct as letter of the code but may not always be enforce
 
Dennis,

310.3 is a good point.

The meter/disco, as described in the OP is back to back with the panel. Depending upon the wall construction, the connection between the two enclosures might be a fitting or two, or a few inches of raceway with two fittings.

The OP question, however, is about the EGC / GEC connection / dual use.

Say the #4 is stranded.
 
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