# External ground wire



## Shorty Circuit (Jun 26, 2010)

I've noticed some designers specify an external equipment ground wire. Personally I've never liked them. Higher impedance, greater physical vulnerability, and the need to attach them to building steel. That last is a problem especially on roofs. What do you guys think? Where are they preferable, where are they required?


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## Dennis Alwon (May 9, 2009)

How do you get around 300.3(B)


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## BBQ (Nov 16, 2010)

Dennis Alwon said:


> How do you get around 300.3(B)


I think what he is seeing is a bonding jumper in addition to the circuit EGC.


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## Shorty Circuit (Jun 26, 2010)

Dennis Alwon said:


> How do you get around 300.3(B)


Excellent question. Yes, there is an option for an external bonding jumper in Exhibit 250.46 in the handbook but it's limited to 6 feet. I still don't like it. As for redundant external grounds to building steel doesn't that create risk of ground loops? At least the internal ground wire and conduit follow the same path and there is redundancy there already. I was just wondering if any of you guys encounter them, I've never used them myself but I see them on so called "grounding plans."


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## BBQ (Nov 16, 2010)

Shorty Circuit said:


> Excellent question. Yes, there is an option for an external bonding jumper in Exhibit 250.46 in the handbook but it's limited to 6 feet.


Regarding 300.3(B), please notice that Equipment grounding conductors and Equipment Bonding conductors are not the same things and have different rules.



> *300.3 Conductors.
> 
> (B) Conductors of the Same Circuit.* All conductors of
> the same circuit and, where used, the grounded conductor
> ...


Very few EGCs can be run outside the raceway.






> As for redundant external grounds to building steel doesn't that create risk of ground loops?


In almost all installations there will be multiple paths to ground, this is not a problem unless this 'ground loop' includes some sort of signal conductor, Data, audio, video etc. 



> I was just wondering if any of you guys encounter them, I've never used them myself but I see them on so called "grounding plans."


Yes, often part of a bonding, grounding and lightning protection scheme that exceeds any NEC requirements.


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## Shorty Circuit (Jun 26, 2010)

BBQ said:


> Regarding 300.3(B), please notice that Equipment grounding conductors and Equipment Bonding conductors are not the same things and have different rules.
> 
> 
> 
> ...


Thanks BBQ. So as I thought these extra external grounds are beyond NEC's requirement. Is there some advantage to this I'm missing or should I spend my clients' discretionary money elsewhere? I am aware of lightning protection but I think I'd provide this if necessary with air terminals that are insulated from equipment and provide entirely separate paths to ground through bare #6 wire also on insulated standoffs.


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## mmiller9 (Jan 2, 2009)

im an oil and gas electrician and everything is bonded with an additional, external, visual bond wire, usually 2/0 or 4/0... stands, panels,jb's, columns, building steel etc. to avoid ground loops in signal wiring (analog plc wiring etc.) the drain/shield is bonded only once at the plc from an isolated bonding conductor that runs right back to the main ground connection. throughout the run to the end device the drain is isolated from main bond, that way there is no ground loop on the signal cable.


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## Mshea (Jan 17, 2011)

There is only 1 real purpose for external ECG or Bond wires is related to preventing voltage rise between 2 points. An external copper bond wire will have a higher impedance than EMT in a fault but put the same wire inside the pipe and it will share fault current closer to 50/50.
Chapter 11 of Soares book on grounding has a great experiment from the 1950's on the subject.


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## chicken steve (Mar 22, 2011)

well we run 'external' solid #8 for jacuzzi's......~CS~


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## Lone Crapshooter (Nov 8, 2008)

I see allot of external grounds in industrial work. I do not like them they are subject to physical damage and they are high impedance.


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## RIVETER (Sep 26, 2009)

Shorty Circuit said:


> I've noticed some designers specify an external equipment ground wire. Personally I've never liked them. Higher impedance, greater physical vulnerability, and the need to attach them to building steel. That last is a problem especially on roofs. What do you guys think? Where are they preferable, where are they required?


As far as I know the EGC should be run as close to the circuit conductors as possible.


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## BBQ (Nov 16, 2010)

Lone Crapshooter said:


> I see allot of external grounds in industrial work. I do not like them they are subject to physical damage and they are high impedance.


Not external EGCs, external bonds, there is a difference.


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## Meadow (Jan 14, 2011)

On motor whips under 7 feet Im pretty sure an external EGC is ok.


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## Shorty Circuit (Jun 26, 2010)

Lone Crapshooter said:


> I see allot of external grounds in industrial work. I do not like them they are subject to physical damage and they are high impedance.


I'm with you on this one. I feel the same way. The only exception is grounding neutrals of transformers. I like to run them inside PVC pipe to protect them and ground the neutral right at the transformer running redundant ground and neutral wires to the first panel. I've met a lot of electricians who like to ground the neutral at the first panel. 

I started this thread because I was looking at some old drawings and came across a "grounding plan." Then I remembered seeing others. They had EGCs which I never uses for branch circuits or feeder circuits. I wondered if I had overlooked something and figured you guys would know if I had. Thanks for all your help and advice.


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## RIVETER (Sep 26, 2009)

Shorty Circuit said:


> I'm with you on this one. I feel the same way. The only exception is grounding neutrals of transformers. I like to run them inside PVC pipe to protect them and ground the neutral right at the transformer running redundant ground and neutral wires to the first panel. I've met a lot of electricians who like to ground the neutral at the first panel.
> 
> I started this thread because I was looking at some old drawings and came across a "grounding plan." Then I remembered seeing others. They had EGCs which I never uses for branch circuits or feeder circuits. I wondered if I had overlooked something and figured you guys would know if I had. Thanks for all your help and advice.


Did I miss something? An EGC would be run with any branch circuit.


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