Grounding 5 main panels

[MannyBurgos]

Hello all,

This Is a question in reference to 2002 NEC. We have a 5 meter gang and 5 main panels (4 for apartments and 1 house meter). A ground rod and water meter GEC are required per local amendment. Is it permissible to terminate GEC for water meter from 1 panel ground busbar to another panel ground busbar and so forth? In effect, the question is can I use the ground busbars from the other panels to terminate my GEC? Thanks all.

 

[augie47]

You can not "loop" from panel to panel. You can terminate and appropriately sized Grounding Electrode at the panel locations and tap from it to each panel.

 

[MannyBurgos]

You can not "loop" from panel to panel. You can terminate and appropriately sized Grounding Electrode at the panel locations and tap from it to each panel.
View attachment 11010

Thanks Augie,
I don't have the NEC in front of me right now but saw that sections of busbars can be used to create the GEC (250.64 excep. I think)... Not in my case?

 

[MannyBurgos]

Thanks Augie,
I don't have the NEC in front of me right now but saw that sections of busbars can be used to create the GEC (250.64 excep. I think)... Not in my case?

250.64(c)(2)

 

[augie47]

Decades of doing this and no one I know has ever read that section and interpreted it that way .. most interesting... and I can't give a fluent answer.
With all the details that are given in 250.64(D), I am confident that (C) is discussing bussbars OTHER than those in individual panels but I can't come up with an answer.

 

[Smart $]

Decades of doing this and no one I know has ever read that section and interpreted it that way .. most interesting... and I can't give a fluent answer.
With all the details that are given in 250.64(D), I am confident that (C) is discussing bussbars OTHER than those in individual panels but I can't come up with an answer.

I believe 250.64(C)(2) means busbar section to section, i.e. not with wire jumpers in between each section. Even if one did use wire for part of the GEC run, each connection to busbar would have to made by irreversible compression or exothermic weld.

In the case of 250.64(D), listed connectors can used, but the busbar has to be acccessible... so that means outside the panels.

 

[MannyBurgos]

I believe 250.64(C)(2) means busbar section to section, i.e. not with wire jumpers in between each section. Even if one did use wire for part of the GEC run, each connection to busbar would have to made by irreversible compression or exothermic weld.

In the case of 250.64(D), listed connectors can used, but the busbar has to be acccessible... so that means outside the panels.

To be made by irreversible compression or exothetmic weld: thats where the exception comes in which says sections of busbars shall be permitted to be connected togetjer to form a grounding rlectrode conductor (and i am still confused on this one). This book is like the bible. Except without the holy grail.

Listed connectors can used but the busbar has to be accessible: what would make the panels inaccessible? They are not readily accessible but are accessible....

 

[MannyBurgos]

Decades of doing this and no one I know has ever read that section and interpreted it that way .. most interesting... and I can't give a fluent answer.
With all the details that are given in 250.64(D), I am confident that (C) is discussing bussbars OTHER than those in individual panels but I can't come up with an answer.

Augie you cant give up. You know the answer. All the residential panels ive seen here in illinois with the same setup have been this way. I just want to clarify if its correct or not.

 

[GoldDigger]

If the inside of a j-box Is accessible, the inside of a panel is too.

 

[augie47]

Augie you cant give up. You know the answer. All the residential panels ive seen here in illinois with the same setup have been this way. I just want to clarify if its correct or not.

In more than one IAEI meeting I was told the "looping" was not allowed as removal of one panel would interrupt the GEC to the remaining panel, however, no one ever backed that statement up by Code. The 2005 Handbook mentions the "taps" were introduced as a method being easier than looping from panel to panel.
Perhaps the loop method is a compliant method. At the moment I can't show otherwise, but I would think that, as the Handbook mentions, the taps would be significantly simpler. If one looped panel to panel it would appear the wire would have to be sized for the sum of the service conductors in all panels and would be prohibitively large for looping.

 

[MannyBurgos]

In more than one IAEI meeting I was told the "looping" was not allowed as removal of one panel would interrupt the GEC to the remaining panel, however, no one ever backed that statement up by Code. The 2005 Handbook mentions the "taps" were introduced as a method being easier than looping from panel to panel.
Perhaps the loop method is a compliant method. At the moment I can't show otherwise, but I would think that, as the Handbook mentions, the taps would be significantly simpler. If one looped panel to panel it would appear the wire would have to be sized for the sum of the service conductors in all panels and would be prohibitively large for looping.

It makes complete sense that removal of a panel would interrupt the GEC for other panels. And yes, you have to use a neutral lug kit in order to properly terminate the #2 awg copper in these 100 amp panels. It makes sense what your saying but im still wondering if the setup is permissible or not.

 

[augie47]

Now that you have pointed out 250.64(C), I would not reject a job wired that way..... but that's just me. I can not show you in the book where it would be a violation.

 

[MannyBurgos]

Now that you have pointed out 250.64(C), I would not reject a job wired that way..... but that's just me. I can not show you in the book where it would be a violation.

Thank you. . I will terminate GEC and see what inspector says on Tuesday. I try to question EVERYTHING. This is for an investor thqt needs code violations repaired as cheap as possible.Taps would be more expensive than neutral lugs.

 

[augie47]

Thank you. . I will terminate GEC and see what inspector says on Tuesday. I try to question EVERYTHING. This is for an investor thqt needs code violations repaired as cheap as possible.Taps would be more expensive than neutral lugs.

That surprises me considering the labor involved. I would have thought the tap would be considerably quicker.

Another point you might keep in mind, IF you are routing the conductor from panel to panel and that route takes the conductor thru a metallic conduit, 250.64(E) comes into play and you would need to bond the each end of the raceway to the conductor. That would definitely not make it less expensive.

 

[MannyBurgos]

That surprises me considering the labor involved. I would have thought the tap would be considerably quicker.

Another point you might keep in mind, IF you are routing the conductor from panel to panel and that route takes the conductor thru a metallic conduit, 250.64(E) comes into play and you would need to bond the each end of the raceway to the conductor. That would definitely not make it less expensive.

Your still required 250.64(e) with a tap. We are required by local AHJ to protect GEC no matter what size with emt or r.m.c. So if i were to bring in taps to a gutter i would still need bonding bushings at both ends of the raceway regardless (unless im wrong). with tap's, i would need a gutter, compression clamps, etc. With loop, i just need neutral lug kit ($3) and some light labor for bends for looping into other panels. Bonding bushings are a given.

 

[John120/240]

........................ This is for an investor that needs code violations repaired as cheap as possible.Taps would be more expensive than neutral lugs.

DO NOT let your customer dictate how you complete the task based on cost ! He owns a four unit apartment building, do you

 

[MannyBurgos]

DO NOT let your customer dictate how you complete the task based on cost ! He owns a four unit apartment building, do you

It's really not about the costs. More than anything, its about following the code to the T but with the run around that the NEC gives us sometimes, it makes it somewhat confusing and im sure that a lot of inspectors feel the same way. While I have done this type of installation for many years as well as other local contractors, I still question if it is indeed the proper way per NEC regardless if inspector has passed it dozens of times in the past. Question everything. At this point, I was concerned with the setup because thinking of a point that Augie made earlier "losing GEC if one of the panels were to be removed" but we can't seem to find anything in NEC that prohibits the loop installation. This was my concern from the beginning and actually, the tap installation would be a more expensive install if you ask me.

 

[Smart $]

To be made by irreversible compression or exothetmic weld: thats where the exception comes in which says sections of busbars shall be permitted to be connected togetjer to form a grounding rlectrode conductor (and i am still confused on this one). This book is like the bible. Except without the holy grail.

Listed connectors can used but the busbar has to be accessible: what would make the panels inaccessible? They are not readily accessible but are accessible....

If the inside of a j-box Is accessible, the inside of a panel is too.

Accessible is just what the Code says... I added the outside the panel part because I believe that is the intent. Yet I'll cede that is not actually what it says.

Nonetheless. 250.64(D) is not an exception. That's for making taps off the GEC (with extreme emphasis) to individual panels. Only under that condition are the taps permitted to be made using listed connectors in lieu of irreversible connections. Additionally, there is no GEC busbar inside panels unless you add one (the busbars in the panel as furnished are at best neutral and equipment ground buses... and when 250.64(A) says you can use sections of busbar connected together to form a GEC, it means section to section (as typically connected together, overlapped and secured with bolts), not using wire jumpers in between sections. If any part of the GEC (again with extreme emphasis) is a wire to busbar connection, it has to be irreversibly connected... unless it is a GEC tap under 250.64(D).

Anyway, if the idea is to be cheap as possible, I have to ask if there is one or several service entrance conductor sets? If just one, the cheapest solution may be to just connect the GEC to the grounded conductor before it splits into several. No tapping or looping required. Of course, that is if such connection isn't restricted local amendments or POCO restrictions.

 

[MannyBurgos]

Accessible is just what the Code says... I added the outside the panel part because I believe that is the intent. Yet I'll cede that is not actually what it says.

Nonetheless. 250.64(D) is not an exception. That's for making taps off the GEC (with extreme emphasis) to individual panels. Only under that condition are the taps permitted to be made using listed connectors in lieu of irreversible connections. Additionally, there is no GEC busbar inside panels unless you add one (the busbars in the panel as furnished are at best neutral and equipment ground buses... and when 250.64(A) says you can use sections of busbar connected together to form a GEC, it means section to section (as typically connected together, overlapped and secured with bolts), not using wire jumpers in between sections. If any part of the GEC (again with extreme emphasis) is a wire to busbar connection, it has to be irreversibly connected... unless it is a GEC tap under 250.64(D).

Anyway, if the idea is to be cheap as possible, I have to ask if there is one or several service entrance conductor sets? If just one, the cheapest solution may be to just connect the GEC to the grounded conductor before it splits into several. No tapping or looping required. Of course, that is if such connection isn't restricted local amendments or POCO restrictions.

You mean we can't tetminate our EGC at the neutral busbar??? Hmmm if i recall, you have to terminate your GEC at the first disconnect and bond your neutral and ground at that point. Point of attachment i believe.... we are looking at 250.64(c) (exception). Busbars are permitted to be connected to form a GEC. Example of connection: 2 cities and a bridge.

Again, the exception is for 250.64(c) where it talks about irreversal connections and such....

 

[Smart $]

You mean we can't tetminate our EGC at the neutral busbar??? Hmmm if i recall, you have to terminate your GEC at the first disconnect and bond your neutral and ground at that point. Point of attachment i believe.... we are looking at 250.64(c) (exception). Busbars are permitted to be connected to form a GEC. Example of connection: 2 cities and a bridge.

Again, the exception is for 250.64(c) where it talks about irreversal connections and such....

Yes you can terminate your GEC (or GEC tap) to the neutral busbar. You can also terminate it at the EGC busbar if there is an appropriately sized wire-type main bonding jumper between neutral and EGC busbars. However, you are permitted to terminate a GEC to and at any point along the grounded [neutral] service entrance conductor. A GEC is only required to be connected within the same enclosure as a system bonding jumper of a separately derived system... not a service.

250.64(C)(2) says sections of busbar. It does not say sections of busbar and wire, nor does it say anything about listed grounding connectors that are not irreversible.