# Grounding panels..



## waco (Dec 10, 2007)

Two meters, two panels, two service entrance conductors to one service drop.

Each panel grounded to the primary ground through separate wires, but...

Two secondary grounds (ground rods) and two separate wires, one from each panel?

Or, one ground rod with one conductor from each panel?

Or, one conductor from one panel to the next panel to one ground rod?

Three different AHJs have passed all three ground rod setups. Anybody know a code reference which defines absolutely what is required for the ground rod?


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## Speedy Petey (Jan 10, 2007)

I typically do two separate GECs from each panel. One water bond/ground, and one rod/ufer.


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## waco (Dec 10, 2007)

You do each panel as if it is a stand alone installation? Probably the safest way to go.


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## mcsinco (Dec 17, 2009)

*Grounding*

You have many options
1) If you have a meter stack then pond all grounds at the meter stack
2) You could also use one wire from each grounding system into each meter and out to the next so long it is not cut.
3) You may think of each panel as its own system (too much work)

You must have two ground rods in any grounding system. So you can have one ground rod for each panel. yet you can use the same ground rods whether, taking a wire from rod 1 to rod 2 then to panel 1 and then panel two, just do not cut the wire. Or two wires from rod 1 to rod 2 and then each wire go to a panel. 

Just so you know the AHJ does not always have a clue what are they doing. For example in a city of Virginia, fire marshals were made city inspectors!! Trust me the don’t know everything.

The code states that the supplementary grounding system must consist of two ground rods. See NEC 250


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## raider1 (Jan 22, 2007)

> You must have two ground rods in any grounding system.


Not necessarily, if I test a single ground rod and that rod has 25 ohms or less then I do not need to supplement that electrode. (See 250.56)

Chris

P.S. why are we responding to a thread that is over a year old?


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## NolaTigaBait (Oct 19, 2008)

Yeah, 2 ground rods required only in one jurisdiction here.


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## user4818 (Jan 15, 2009)

NolaTigaBait said:


> Yeah, 2 ground rods required only in one jurisdiction here.


:blink:


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## LAElectrician (Dec 8, 2009)

waco said:


> Two meters, two panels, two service entrance conductors to one service drop.
> 
> Each panel grounded to the primary ground through separate wires, but...
> 
> ...


Any of these three methods should meet NEC requirements. 

I just completed (and passed) a job like this. I installed (2) three phase, 400 amp services side-by-side. I ran 1 unbroken ground wire from one service, through the other service, and on to the cold water ground, which was 150' away. Not running two separate 3/0 ground wires 150' saved me a lot of money. 

For the secondary ground I used 2 separate ground rods. It was simplest to put one under each 400 amp stand-up service, although I could have used the same (1 unbroken ground wire) method with just one ground rod.


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## NolaTigaBait (Oct 19, 2008)

It doesn't necessarily have to be unbroken.


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## Speedy Petey (Jan 10, 2007)

mcsinco said:


> *You must have two ground rods in any grounding system.* So you can have one ground rod for each panel. yet you can use the same ground rods whether, taking a wire from rod 1 to rod 2 then to panel 1 and then panel two, just do not cut the wire. Or two wires from rod 1 to rod 2 and then each wire go to a panel.
> 
> Just so you know the AHJ does not always have a clue what are they doing. For example in a city of Virginia, fire marshals were made city inspectors!! Trust me the don’t know everything.
> 
> *The code states that the supplementary grounding system must consist of two ground rods. See NEC 250*


Really??? Where do you find the requirement for two "ground rods"?

Also, are you sure about your use of the word "supplementary", and that again two rods are mandatory? 

I suggest you yourself go back and read Art. 250.


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## Dennis Alwon (May 9, 2009)

mcsinco said:


> You must have two ground rods in any grounding system. So you can have one ground rod for each panel. yet you can use the same ground rods whether, taking a wire from rod 1 to rod 2 then to panel 1 and then panel two, *just do not cut the wire. *


Some of your concepts on grounding are not quite correct. The GEC does not have to be continuous thru the entire GEC system. There are some good graphics floating around. I'll see if I can find one.








I found it


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## LAElectrician (Dec 8, 2009)

NolaTigaBait said:


> It doesn't necessarily have to be unbroken.


Every service panel must have an unbroken wire running to its grounding source. In other works, you can't cut the ground wire anywhere from the panel to the grounding source (c.w.ground, ground rod, ufer).

If two services are going to share the same grounding wire, that wire must be unbroken for each of the services. That can be accomplished by starting at one service panel, running the ground wire to the other service panel and stripping off some of the wire's insulation without cutting the wire, and then continuing on with the same unbroken ground wire to the grounding source.


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## Dennis Alwon (May 9, 2009)

LAElectrician said:


> If two services are going to share the same grounding wire, that wire must be unbroken for each of the services. That can be accomplished by starting at one service panel, running the ground wire to the other service panel and stripping off some of the wire's insulation without cutting the wire, and then continuing on with the same unbroken ground wire to the grounding source.


I do not agree. I believe that you run the GEC from one panel to the water pipes and split bolt from that wire to the other panel as long as the wire is large enough for the services.


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## NolaTigaBait (Oct 19, 2008)

Dennis Alwon said:


> I do not agree. I believe that you run the GEC from one panel to the water pipes and split bolt from that wire to the other panel as long as the wire is large enough for the services.


I agree with Dennis. He's usually right about this kind of stuff:thumbsup:


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## Dennis Alwon (May 9, 2009)

NolaTigaBait said:


> I agree with Dennis. He's usually right about this kind of stuff:thumbsup:


Thanks but grounding and bonding are not my forte.


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## NolaTigaBait (Oct 19, 2008)

Dennis Alwon said:


> Thanks but grounding and bonding are not my forte.


Good enough:thumbsup:


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## electures (Oct 23, 2008)

mcsinco said:


> You have many options
> 1) If you have a meter stack then pond all grounds at the meter stack
> 2) You could also use one wire from each grounding system into each meter and out to the next so long it is not cut.
> 3) You may think of each panel as its own system (too much work)
> ...


250.53 reads as follows;

*(D) Metal Underground Water Pipe.​*​​​​Where used as a grounding electrode, metal underground water pipe shall meet the requirements of 250.53(D)(1) and (D)(2).​
*(1) Continuity.​*​​​​Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment.​
*(2) Supplemental Electrode Required.​*​​​​A metal underground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) through
(A)(8). Where the supplemental electrode is a rod, pipe, or plate type, it shall comply with 250.56. The supplemental electrode shall be permitted to be bonded to the grounding
electrode conductor, the grounded service-entrance conductor, the nonflexible grounded service raceway, or any grounded service enclosure.​
 
Where is it written "*the supplementary grounding system must consist of two ground rods.":blink:*


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## Dennis Alwon (May 9, 2009)

electures said:


> Where is it written "*the supplementary grounding system must consist of two ground rods.":blink:*


Right here indirectly depending on conditions.



> 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)(4) through (A)(8). *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.
> FPN: The paralleling efficiency of rods longer than 2.5 m (8 ft) is improved by spacing greater than 1.8 m (6 ft).


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## electures (Oct 23, 2008)

raider1 said:


> Not necessarily, if I test a single ground rod and that rod has 25 ohms or less then I do not need to supplement that electrode. (See 250.56)
> 
> Chris
> 
> P.S. why are we responding to a thread that is over a year old?


Absolutely correct :thumbup:

Building steel, ground ring, plates, concrete encased, or ufer grounds do not require a supplementary grounding electrode either.


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## LAElectrician (Dec 8, 2009)

Dennis Alwon said:


> I do not agree. I believe that you run the GEC from one panel to the water pipes and split bolt from that wire to the other panel as long as the wire is large enough for the services.


Yes, what you describe is a perfectly correct way to ground two panels. Either way is correct as long as both panels are connected to the grounding source with an unbroken GEC.

I have used both methods, depending on jobsite circumstances. In the job I just finished, the cold water was 150 feet away from the two services. While both grounding methods we've been discussing meet NEC requirements, I'd rather use 150' of 3/0 than 300' of 3'0.


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## NolaTigaBait (Oct 19, 2008)

I can make an irreversible connection to the gec also. I would try not to do it, but it is legal. Still doesn't have to be unbroken.


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## Dennis Alwon (May 9, 2009)

NolaTigaBait said:


> I can make an irreversible connection to the gec also. I would try not to do it, but it is legal. Still doesn't have to be unbroken.


C'est vrai ( This is true)


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## electures (Oct 23, 2008)

Dennis Alwon said:


> Right here indirectly depending on conditions.


I agree. The point I was trying to make was that the first rod (single) is the supplemental grounding electrode. If the impedence of the first rod exceeds 25 ohms then it shall be;

*augmented* by one additional electrode of any of the types specified by 250.52(A)(4) through (A)(8). 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.

He makes it sound like both rods are required to be installed together to make up the supplementary grounding electrode. The second rod augments the first rod. If the impedence is less than 25 ohms no additional rod is required.

Here in the Great Police State of New Jersey I do not require two rods. I offer the EC the choice between meeting me at the job site where I can witness the ground rod being megged ( I have one day to schedule the inspection then three days to complete the inspection = four days), or drive the second rod and be done with it. 

Now before somebody gets their panties in a bunch I need to explain how inspections work here. The Code Enforcement Office has 24 hours to schedule an inspection then the inspector has three days to complete the inspection. This translates to four days. No work shall not procede in any way that will interfere with inspections. If the inspector fails to complete the inspection within the state mandated time the work *shall not continue.* The only repercussion the contractor has is to file a complaint with the DCA.

While I have never taken more then one day to complete an inspection, it can and does happen. The bottom line is if a contractor has to wait even one hour for me to show up and witness the test he is losing money. That is why it is cheaper to drive the second rod.

My personal approach to inspecting is what can I do to facilitate the work and obtain code compliance. Unfortunately not all inspectors approach it that way.

Sorry for being long winded!!:blink:

L8R, Kevin​


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## Dennis Alwon (May 9, 2009)

I think we are all guilty of saying 2 rods are required, at least, I am guilty of it. It is generally the status quo because most places cannot obtain 25 ohms so many of us just say 2 grounds are required. Of course this is not true some of the time esp. if a UFER is present and used.


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## electures (Oct 23, 2008)

Dennis Alwon said:


> I do not agree. I believe that you run the GEC from one panel to the water pipes and *split bolt* from that wire to the other panel as long as the wire is large enough for the services.


250.64(D) (1) states;

*(D) Service with Multiple Disconnecting Means Enclosures.*
Where a service consists of more than a single enclosure as permitted in 230.71(A), grounding electrode connections shall be made in accordance with (D)(1),
(D)(2), or (D)(3). ​

​​*(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.*​

What this is refering to is that the *ground bar* is listed as grounding and bonding equipment. Therefore the connection is permited to be made on the equipment ground bar in each service disconnect, exothermic welding or irreversible compression connectors. I would question whether or not the split bolt is listed as "*grounding and bonding equipment ". *​ 
*L8R, Kevin:thumbsup:*​


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## NolaTigaBait (Oct 19, 2008)

You could question it, but it's got that little ul listing stamp that says it is. I've read some of your posts, man you come up with some ****.


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## electures (Oct 23, 2008)

NolaTigaBait said:


> You could question it, but it's got that little ul listing stamp that says it is. I've read some of your posts, man you come up with some ****.


 
Hi Nola,

Be careful, even though it has a label it has to installed per the listing and labeling, and the manufacturers installation instructions. An example would be a water pipe ground clamp being installed on a ground rod. It isn't listed for the use, but it has a label.

The NEC requires that it be listed for grounding and bonding. It has to meet the requirements of UL 467. If it does not meet UL 467 it does not comply.

L8R, Kevin


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## Bob Badger (Apr 19, 2009)

LAElectrician said:


> Every service panel must have an unbroken wire running to its grounding source. In other works, you can't cut the ground wire anywhere from the panel to the grounding source (c.w.ground, ground rod, ufer).
> 
> If two services are going to share the same grounding wire, that wire must be unbroken for each of the services. That can be accomplished by starting at one service panel, running the ground wire to the other service panel and stripping off some of the wire's insulation without cutting the wire, and then continuing on with the same unbroken ground wire to the grounding source.



I strongly urge you to try and find code sections to support you're view.

Here is a NEC Handbook example.










The taps can be made with split bolts.

Check out 250.64(D)





> *250.64(D) Grounding Electrode Conductor Taps.* Where a service consists of more than a single enclosure as permitted in 230.40, Exception No. 2, it shall be permitted to connect taps to the grounding electrode conductor. Each such tap conductor shall extend to the inside of each such enclosure. The grounding electrode conductor shall be sized in accordance with 250.66, but the tap conductors shall be permitted to be sized in accordance with the grounding electrode conductors specified in 250.66 for the largest conductor serving the respective enclosures. The tap conductors shall be connected to the grounding electrode conductor in such a manner that the grounding electrode conductor remains without a splice.


*It is important to realize that only the GEC has to be continuous, not the bonding jumpers between electrodes.*

Check out this other Handbook example.












There is nothing wrong with using one continuous conductor from electrode to electrode but it can be a real pain and is not required by the NEC.


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## LAElectrician (Dec 8, 2009)

Quote:
Originally Posted by *NolaTigaBait*  
_I can make an irreversible connection to the gec also. I would try not to do it, but it is legal. Still doesn't have to be unbroken._


__________________



Dennis Alwon said:


> C'est vrai ( This is true)


I agree. NEC 250.64(C) states that a GEC must be continuous UNLESS spliced by irreversible compression-type connectors listed for the purpose or by exothermic weld.


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## LAElectrician (Dec 8, 2009)

Bob Badger said:


> I strongly urge you to try and find code sections to support you're view.
> 
> Here is a NEC Handbook example.
> 
> ...


Bob, *250.64(D) Grounding Electrode Conductor Taps *says:Where a service consists of more than a single enclosure as permitted in 230.40, Exception No. 2, it shall be permitted to connect taps to the grounding electrode conductor.

My earlier posts have been referring to the grounding of two separate services, not a single service with two or more separate enclosures.


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## Bob Badger (Apr 19, 2009)

LAElectrician said:


> Quote:
> Originally Posted by *NolaTigaBait*
> _I can make an irreversible connection to the gec also. I would try not to do it, but it is legal. Still doesn't have to be unbroken._
> 
> ...



Unless it's a GEC tap as allowed by 250.64(D)

OR

It is not the GEC but just a bonding jumper connecting a group of electrodes per 250.64(F)


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## Bob Badger (Apr 19, 2009)

LAElectrician said:


> Bob, *250.64(D) Grounding Electrode Conductor Taps *says:Where a service consists of more than a single enclosure as permitted in 230.40, Exception No. 2, it shall be permitted to connect taps to the grounding electrode conductor.
> 
> My earlier posts have been referring to the grounding of two separate services, not a single service with two or more separate enclosures.



Well I do not think the OP has two services as he has one drop.

But regardless, it make no difference, if you have a large building with a service at each end there is no requirement to have an unbroken conductor from one service to the electrodes and on to the next service.

If this building happened to be a steel framed one I would simple have to run an unbroken GEC from each service to the closest steel frame member and use the steel frame itself as the connection from service to service just as this handbook example shows.


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## NolaTigaBait (Oct 19, 2008)

Bob, what if one of the panels is a 3 phase power panel without a neutral to it. Can I still run a ge tap to each panel from the gec? Or, do I need to run a neutral to the power panel?


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## electures (Oct 23, 2008)

NolaTigaBait said:


> Bob, what if one of the panels is a 3 phase power panel without a neutral to it. Can I still run a ge tap to each panel from the gec? Or, do I need to run a neutral to the power panel?


250.24(C) reads;

*
(C) Grounded Conductor Brought to Service Equipment.​*​​​​Where an ac system operating at less than 1000 volts is grounded at any point, the grounded conductor(s) *shall be run to each service disconnecting means and shall be connected to each disconnecting means grounded conductor (s) terminal or bus.* A main bonding jumper shall connect the grounded conductor(s) to each service disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with 250.24(C)(1) through (C)(3).​


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## NolaTigaBait (Oct 19, 2008)

electures said:


> 250.24(C) reads;
> 
> *
> (C) Grounded Conductor Brought to Service Equipment.​*Where an ac system operating at less than 1000 volts is grounded at any point, the grounded conductor(s) *shall be run to each service disconnecting means and shall be connected to each disconnecting means grounded conductor (s) terminal or bus.* A main bonding jumper shall connect the grounded conductor(s) to each service disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with 250.24(C)(1) through (C)(3).​


Ok, so whether or not a neutral is needed, I still need to run a neutral to it. Thanks. That solves that.


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## nolabama (Oct 3, 2007)

NolaTigaBait said:


> Ok, so whether or not a neutral is needed, I still need to run a neutral to it. Thanks. That solves that.


Unless its an ungrounded system with Ground Fault alarms and such. For what they are posting about in this thread this is irrelevant.


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## NolaTigaBait (Oct 19, 2008)

nolabama said:


> Unless its an ungrounded system with Ground Fault alarms and such. For what they are posting about in this thread this is irrelevant.


I kinda thought that I needed to run one, no matter what, and then you think ....if you don't need it then why? I'm sure it's for clearing faults.


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## nolabama (Oct 3, 2007)

NolaTigaBait said:


> I kinda thought that I needed to run one, no matter what, and then you think ....if you don't need it then why? I'm sure it's for clearing faults.


You are correct sir. Thats why you gotta have alarms on the Ungrounded systems to alert you of a fault.


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## NolaTigaBait (Oct 19, 2008)

nolabama said:


> You are correct sir. Thats why you gotta have alarms on the Ungrounded systems to alert you of a fault.


And you act like you don't know anything.:jester:


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## nolabama (Oct 3, 2007)

NolaTigaBait said:


> And you act like you don't know anything.:jester:



Book learnin' my friend book learnin' 

I was with a process control 'lectrician the other day that had the relays tore out of his truck when I rolled up. He said "troubleshooting one o one" Had a fuel pump problem. I asked if he had gas in the tank. He did not.:laughing:


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## NolaTigaBait (Oct 19, 2008)

nolabama said:


> Book learnin' my friend book learnin'
> 
> I was with a process control 'lectrician the other day that had the relays tore out of his truck when I rolled up. He said "troubleshooting one o one" Had a fuel pump problem. I asked if he had gas in the tank. He did not.:laughing:


The simplest things. :laughing:


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## electures (Oct 23, 2008)

NolaTigaBait said:


> Ok, so whether or not a neutral is needed, I still need to run a neutral to it. Thanks. That solves that.


Yes. 

250.24(C)1 reads;


*(1) Routing and Sizing. *
*This conductor shall be routed with the phase conductors and shall not be smaller than the required grounding electrode conductor specified in Table 250.66* but shall not be required to be larger than the largest ungrounded service-entrance phase conductor. In addition, for service-entrance phase conductors larger than 1100 kcmil copper or 1750 kcmil aluminum, the grounded conductor shall not be smaller than 12 1⁄2 percent of the area of the largest service-entrance phase conductor. The grounded conductor of a 3-phase, 3-wire delta service shall have an ampacity not less than that of the ungrounded conductors.
 

Table 250.66 is used for three things;
1. Size the GEC
2. Size the grounded service conductor (neutral) brought to the service disconnect.
3. Size the main bonding jumper.

The difference between the three items is that the GEC is not required to be larger than the table. However, the grounded service conductor and the MBJ will continue to increase at 12 1/2% the size of the ungrounded service conductor. 

Some don't know how to size the MBJ because it usually is supplied with the service equipment in the form of a green screw or a bracket. If the green screw or the bracket were lost, 250.66 will size the conductor needed to bond the panel.

L8R, Kevin​


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## NolaTigaBait (Oct 19, 2008)

Yeah, I knew the rest and how to size it. I was unsure about routing it. I have alot of info rolling around up there:jester:


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