GEC & Bonding?

jahilliard

Senior Member
Ok, so after doing a residential service change we failed for the following reasons. 1. #6 bare Cu GEC to the water pipe needs to be #4 Cu. 2. No groundng bushing on the 2" nipple between the Meter enclosure and the new WP Panel. (Note. The new panel is a solid opening/non-concentric and has two locknuts holding it in place and that panel is bonded). I am under the impression that a #6 Cu is sufficient according to 250.66(A) and that there is no need for the grounding bushing on the nipple due to the fact that a solid grounded conductor runs from the meter to the bonded electrical panel. When I asked about the water pipe it was ROUGHLY explained that the "water system" must be bonded and that it has nothing to do with the GEC. FYI, the "water system" is CPVC other than a very short piece of copper on the outside. The explanation I received from the inspector was very unclear and that's why I am asking for more clarification here. We are working in a new area and these inspectors are not familiar with our work and vice versa so I am trying to learn what they are expecting.
 

iwire

Moderator
Staff member
Location
Massachusetts
1. #6 bare Cu GEC to the water pipe needs to be #4 Cu. 2. No groundng bushing on the 2" nipple between the Meter enclosure and the new WP Panel. (Note. The new panel is a solid opening/non-concentric and has two locknuts holding it in place and that panel is bonded). I am under the impression that a #6 Cu is sufficient according to 250.66(A) and that there is no need for the grounding bushing on the nipple due to the fact that a solid grounded conductor runs from the meter to the bonded electrical panel. When I asked about the water pipe it was ROUGHLY explained that the "water system" must be bonded and that it has nothing to do with the GEC. FYI, the "water system" is CPVC other than a very short piece of copper on the outside. The explanation I received from the inspector was very unclear and that's why I am asking for more clarification here. We are working in a new area and these inspectors are not familiar with our work and vice versa so I am trying to learn what they are expecting.

I am under the impression that a #6 Cu is sufficient according to 250.66(A)
250.66(A) applies to ground rods, you said water pipe.

and that there is no need for the grounding bushing on the nipple due to the fact that a solid grounded conductor runs from the meter to the bonded electrical panel
Sorry but no.

250.92 Services.
(A) Bonding of Equipment for Services.
The normally
non–current-carrying metal parts of equipment indicated in
250.92(A)(1) and (A)(2) shall be bonded together.

(1) All raceways, cable trays, cablebus framework, auxiliary
gutters, or service cable armor or sheath that enclose,
contain, or support service conductors, except as
permitted in 250.80

(2) All enclosures containing service conductors, including
meter fittings, boxes, or the like, interposed in the service
raceway or armor
 

mwm1752

Senior Member
Location
Aspen, Colo
I can only summize your service condutors are smaller than 2/0 CU or 4/0 AL ---- your GRC nipple is not installed in any concentric or eccentric KO's -- and you have already stated the water piping system is not metal -- If all assumptions are true you have an arguement to win
 

iwire

Moderator
Staff member
Location
Massachusetts
I can only summize your service condutors are smaller than 2/0 CU or 4/0 AL ---- your GRC nipple is not installed in any concentric or eccentric KO's -- voltage is less than 250v to grd -- and you have already stated the water piping system is not metal -- If all assumptions are true you have an arguement to win
The conduit needing bonding is a 2" between the meter and the panel.

No groundng bushing on the 2" nipple between the Meter enclosure and the new WP Panel
The AHJ may require bonding of the metal section of water line.

"water system" is CPVC other than a very short piece of copper on the outside
 

jahilliard

Senior Member
Ok. What requires that water pipe to be grounded if it's not a pipe electrode? (250.66(A) Rod, PIPE or Plate electrodes) and if the nipple is considered bonded on the panel side, why does it need to be bonded on the meter side when the solid/continuous GEC bonds the meter enclosure? If I don't fully underrstand, it's impossible for me to explain it to the installers.
 

jahilliard

Senior Member
We used 4/0 Al, the reference I was making is to 250.66(A) that doesmnt require that water pipe bond to be larger than #6. I am aware of Table 250.66
 

iwire

Moderator
Staff member
Location
Massachusetts
Ok. What requires that water pipe to be grounded if it's not a pipe electrode? (250.66(A) Rod, PIPE or Plate electrodes)
The 'pipe' in 250.66(A) is not a water pipe, it is a pipe pounded in the ground in place of a rod as described in 250.52(A)(5)(a)

(5) Rod and Pipe Electrodes. Rod and pipe electrodes shall
not be less than 2.44 m (8 ft) in length and shall consist of the
following materials.

(a) Grounding electrodes of pipe or conduit shall not be
smaller than metric designator 21 (trade size 3⁄4) and, where of
steel, shall have the outer surface galvanized or otherwise
metal-coated for corrosion protection.


(b) Rod-type grounding electrodes of stainless steel
and copper or zinc coated steel shall be at least 15.87 mm
(5⁄8 in.) in diameter, unless listed.

What requires that water pipe to be grounded if it's not a pipe electrode?

Fair question,

250.104 Bonding of Piping Systems and Exposed Structural
Steel.
(A) Metal Water Piping. The metal water piping system
shall be bonded as required in (A)(1), (A)(2), or (A)(3) of
this section. The bonding jumper(s) shall be installed in
accordance with 250.64(A), (B), and (E). The points of
attachment of the bonding jumper(s) shall be accessible.
There is more to it and worth a look.

Is a short section of metal pipe a metal water piping system?

In my mind no, but it seems like your inspector feels otherwise, the path of least resistance may be to just do it.
 

mwm1752

Senior Member
Location
Aspen, Colo
The conduit needing bonding is a 2" between the meter and the panel.



The AHJ may require bonding of the metal section of water line.

True Simply done with a bonding type locknut

I could see a single branch of copper from a plastic water system but to bond a 18" spicket is a bit over kill IMO how would the small section be energized??
 

mwm1752

Senior Member
Location
Aspen, Colo
We used 4/0 Al, the reference I was making is to 250.66(A) that doesmnt require that water pipe bond to be larger than #6. I am aware of Table 250.66
my table for bonding says 4/0 to 250 MCM AL is a #4 CU 250.66(A) is for the electrode system -- your bonding jumper to water pipe is not as an electrode conductor
 

iwire

Moderator
Staff member
Location
Massachusetts
I could see a single branch of copper from a plastic water system but to bond a 18" spicket is a bit over kill IMO how would the small section be energized??
No argument from me.

It might be more likely to be energized by connecting it to the grounding electrode system as could happen with loss of connection to the utilities neutral. With an open service neutral everything connected to the GES can be above earth potential.
 

infinity

Moderator
Staff member
Location
New Jersey
The nipple is a service raceway since it contains service entrance conductors. Service raceways require bonding by an approved method that goes beyond standard locknuts. {250.92(B)}
 

jahilliard

Senior Member
Ok I started to reply saying I now understand BUT then I read the section again and seems it can be translated that Standard Locknuts or bushing shall not be the only means for bonding required WHEN there is an impaired connection. In this case their is not an impaired connection. I promise I don't mean to be difficult, it's truly how I'm translating this particular section, as referring to impaired connections. And I do better understand the "PIPE" electrode and water system scenario, although I don't fully understand how this particular scenario would in any way require this water system to be bonded.
 

infinity

Moderator
Staff member
Location
New Jersey
It's there in 250.92(B).

250.92(B) Method of Bonding at the Service. Bonding jumpers
meeting the requirements of this article shall be used around
impaired connections, such as reducing washers or oversized,
concentric, or eccentric knockouts. Standard locknuts or bushings shall not be the only means for the bonding required by
this section
but shall be permitted to be installed to make a mechanical connection of the raceway(s).
Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by
one of the following methods:
(1) Bonding equipment to the grounded service conductor
in a manner provided in 250.8
(2) Connections utilizing threaded couplings or threaded
hubs on enclosures if made up wrenchtight
(3) Threadless couplings and connectors if made up tight
for metal raceways and metal-clad cables
(4) Other listed devices, such as bonding-type locknuts,
bushings, or bushings with bonding jumpers
 

Dexie123

Senior Member
Bonding locknuts are not a standard locknut. IMO they satisfy the requirements of 250.92 especially in terms of these particular openings are not impaired.
 

jahilliard

Senior Member
again... this section specifically addresses "impaired connections"...and then describes such connections like concentric knockouts, loose washers etc.. Is this section not specifically addressing impaired connections and the fact that locknuts shall not be used as the only means to bond?
 

Smart $

Esteemed Member
Location
Ohio
again... this section specifically addresses "impaired connections"...and then describes such connections like concentric knockouts, loose washers etc.. Is this section not specifically addressing impaired connections and the fact that locknuts shall not be used as the only means to bond?
Impaired connections are addressed, but not the topic.

The topic is bonding. Such bonding shall not rely solely on standard locknuts or bushings.

Where a connection is impaired, the bonding means shall include a bonding jumper around the impaired connection. Where a connection is not impaired, you may use a means which does not involve a bonding jumper.
 

jahilliard

Senior Member
Ok, that was my translation as well...so why would we be required to install a bonding bushing when the conduit was considered bonded on one side already due to the fact there was not an impaired connection? When my guys called me to ask if a bonding bushing was required I said No because one side of the conduit is considered bonded (no impaired connections). So I am now trying to understand why we failed and were required to install the bushing so that I can explain it to my guys. At this point I still consider the conduit bonded properly....is it required on both ends?? That seems silly to me.
 

iwire

Moderator
Staff member
Location
Massachusetts
At this point I still consider the conduit bonded properly....is it required on both ends?? That seems silly to me.
That is always a question and perhaps the NEC does not specifically require it but it seems many AHJs do.

The requirements are stringent because we are dealing with unfused conductors that can easily pass enough current to blow out a marginal connection.
 

jahilliard

Senior Member
fair enough...it's a 2" nipple so it seems really silly to me and not to mention I have to be able to explain this to employees. I really don't like doing something because someone simply said to...that can make things really confusing. I am grateful for the patience and feedback!
 

Smart $

Esteemed Member
Location
Ohio
Ok, that was my translation as well...so why would we be required to install a bonding bushing when the conduit was considered bonded on one side already due to the fact there was not an impaired connection?....
I'm uncertain we are on the same page here. There are only two variations this conduit-to-enclosure bonding: 1) impaired, and 2) not impaired. In both cases you must use a bonding means enumerated or exemplified in the last paragraph of 250.92(B). The means listed are in addition to or in lieu of standard locknuts or bushings. One of the methods must be used. In the case of an impaired connection, you must use one the means which includes a bonding jumper that goes around the impaired connection.

For example, you can us a bonding locknut for an unimpaired connection. You cannot use a bonding locknut on an impaired connection.
 
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