EGC used as GEC?

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iwire

Moderator
Staff member
Location
Massachusetts
I think the code is totally wrong about the need for a GEC for a transformer that is located within the same building as the service disconnect.
I do not disagree with you. :smile:



Along with that, I think most if not all non-believers are so rapt up in trying to follow [or make] the letter of the "code", they forget about the elemental physics of the application and purpose.
Regardless of the 'elemental physics of the application' :rolleyes: I believe the CMPs intent is to run a separate conductor for the GEC.

As the code is presently written I see it as ambiguous, we will have to see what the 2011 brings. :smile:
 

radiopet

Senior Member
Location
Spotsylvania, VA
The big question when you start talking "intent" on this matter is are you talking intent for specifying an EGC as an EGC, and a GEC as a GEC, or are you talking intent as to whether the purposes of these grounding conductors can be met with one conductor? While neither perspective is mutually exclusive of the other, it seems to me that people take an opinionated stance as though they are.
Their is only but one intent of what the OP is asking. I happen to disagree with his reasoning process. I can only believe what I believe and the way it is written now I believe you must treat the GEC and EGC ( again in the original question, not the elaborate movement into talking about SDS's portion of everyones conversation ) individually in the intent.

We will see what the 2011 brings us regarding this.
 

sandsnow

Senior Member
There is a proposal to allow the EGC to be used as the GEC. The submitter did not do a good job IMO is substantiating the proposal. Maybe someone will make a comment on it.

_______________________________________________________________
5-112 Log #4368 NEC-P05 Final Action: Reject
(250.30(A)(3) Exception No. 4)
_______________________________________________________________
Submitter: Terry L. Schneider, Berwick Electric Co.
Recommendation: Add the following new text:
Where the grounding conductor used for bonding the primary of a separately
derived system is a wire and is sized in accordance with 250.30(A)(2) shall be
permitted to be used as the grounding electrode conductor if it meets the
requirements of 250.30(A)(7) and is installed in accordance with 250.64.
Substantiation: It is unclear in the code, (many jurisdictions prohibit) if it is
permissible to install the grounding electrode conductor with the supply
conductors for a separately derived system. Some jurisdictions are requiring a
separate conductor for the primary ground and another for the grounding
electrode conductor when they terminate in the same place on both ends. This
will help clarify the intent of the code panel.
Panel Meeting Action: Reject
Panel Statement: CMP-5 has created a new definition for a supply-side
bonding jumper that is installed from the source of a separately derived system
to the first system disconnecting means. Its function and location in the
separately derived system does not allow it to be used as an equipment
grounding conductor.
Number Eligible to Vote: 16
Ballot Results: Affirmative: 16
_______________________________________________________________
 

sandsnow

Senior Member
Update. Just found this proposal. If this goes through it will be clear that you need a GEC in addition to your EGC.

_______________________________________________________________
5-259 Log #4526 NEC-P05 Final Action: Accept
(250.108 (New) )
_______________________________________________________________
Submitter: Phil Simmons, Simmons Electrical Services
Recommendation: Create a new Section 250.108 as follows:
250.108 Use of Equipment Grounding Conductors.
An equipment grounding conductor shall not be used as a grounding electrode
conductor.
Substantiation: This new section will clarify that grounding electrode
conductors and equipment grounding conductors serve a different purpose in
the electrical safety system, are sized differently and have different installation
requirements. Equipment grounding conductors do not normally carry current
while a grounding electrode conductor may normally carry current since it is
often in parallel with the neutral conductor.
Panel Meeting Action: Accept
Panel Statement: The panel notes that this new section is to be located in Part
VI and suggests it be numbered as Section 250.121.
Number Eligible to Vote: 16
Ballot Results: Affirmative: 16
_______________________________________________________________
 

sandsnow

Senior Member
Another update. It looks as though you can still use a common Raceway for the GEC, if this goes through.

5-201 Log #2731 NEC-P05 Final Action: Reject
(250.64(F)(4))
_______________________________________________________________
Submitter: James A. Burch, City of Glendale, Arizona
Recommendation: Add paragraph (4) as follows:
(4) Grounding electrode conductor(s) shall not be routed within the same
raceway as premises wiring except within the enclosure where the connection
to grounded conductor is made.
Substantiation: Routing of a grounding electrode conductor with premises
wiring may subject the wiring systems to over voltages created by the utility or
lightning.
The Code does not restrict the routing of the GEC. If raceways are bonded at
both ends, the Code, as now written, is complied with. If raceways are ferrous,
most induced lightning current and associated voltage stress is routed along the
outside of the raceway and may protect any conductors inside the raceway but
if PVC or aluminum raceways are used any conductors will be subject to high
voltage stress possibly damaging the cable as well as any equipment served by
the conductors.
Panel Meeting Action: Reject
Panel Statement: There was no documented evidence in the substantiation that
a problem exists with the current requirements covering the routing of the
grounding electrode conductor.
Number Eligible to Vote: 16
Ballot Results: Affirmative: 16
 

erickench

Senior Member
Location
Brooklyn, NY
NEC 250.24(D) state's the following:

A grounding electrode conductor shall be used to connect the equipment grounding conductors, the service equipment enclosures, where the system is grounded, the grounded service conductor to the grounding electrode.

Note the words: where the system is grounded

I would think the grounding terminal bar inside the service panel/disconnect would be your best bet.:grin:
 

electricalperson

Senior Member
Location
massachusetts
if we had a transformer in a seperate building would we need to run a GEC inside the pipe along with 3 phase conductors and an EGC? i was always confused with this. i believe we need to keep them seperate correct?
 

benaround

Senior Member
Location
Arizona
if we had a transformer in a seperate building would we need to run a GEC inside the pipe along with 3 phase conductors and an EGC? i was always confused with this. i believe we need to keep them seperate correct?
No, You would run the 3 phase and EGC, then at the seperate building install a seperate

GES.
 

electricalperson

Senior Member
Location
massachusetts
No, You would run the 3 phase and EGC, then at the seperate building install a seperate

GES.
but does the transformer XO bonding need to be connected to the buildings electrode? im thinking it has to be bonded to the building that supplies the transformers grounding system then attach the GES at the seperate building to that. not really sure if its in the code or not

im confused about this. maybe all it needs is the GES at the seperate building? the EGC would bond it to the building anyway
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
NEC 250.24(D) state's the following:

A grounding electrode conductor shall be used to connect the equipment grounding conductors, the service equipment enclosures, where the system is grounded, the grounded service conductor to the grounding electrode.

Note the words: where the system is grounded

I would think the grounding terminal bar inside the service panel/disconnect would be your best bet.:grin:
Eric,
You left out a key word in your quote of 250.24(D).
(D) Grounding Electrode Conductor. A grounding electrode conductor shall be used to connect the equipment grounding conductors, the service-equipment enclosures, and, where the system is grounded, the grounded service conductor to the grounding electrode(s) required by Part III of this article. This conductor shall be sized in accordance with 250.66.
The "where" in this code section does not have anything to do with the physical location of the point of connection. It is just telling you that when you have a grounded service conductor, then you have to connect the GEC to it. The location of this connection is covered in 250.24(A)(1).
 

Smart $

Esteemed Member
Location
Ohio
but does the transformer XO bonding need to be connected to the buildings electrode? ...
Yes, if it is a grounded system (highly likely, but covering all possibilities).

... im thinking it has to be bonded to the building that supplies the transformers grounding system then attach the GES at the seperate building to that. not really sure if its in the code or not
That's how it goes. There's no requirement to "bond" the grounding of the two systems... but if all the requirements of grounding the two systems are met, the two systems grounding will be bonded together.

im confused about this. maybe all it needs is the GES at the seperate building? the EGC would bond it to the building anyway
Rules are rules :grin:

...and names are often misnomers. Take for example the separate structure scenario. Just because you run an EGC between structures, what are the chances that an overvoltage induced by a lightning strike nearby knows that this EGC is called an EGC and therefore does not send any current through it to all grounding electrodes attached to both systems. This is my main gripe about trying to disassociate the two types of conductors.

There are also many instances where current goes through branch circuit EGC because they are bonded to so-called non-current carrying metal which is also connected to grounding electrodes via mounting and securing... for example runs of metal conduit using conductive fasteners attached to structural steel, which is also connected by welds and bolting to the metal frame of the structure, which is also a grounding electrode. Does anyone think for a second this path has no current on it when there is current on the grounding electrode system???
 
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