2 Ground rods ?

[hardhat269]

A contractor complained to me that an inspector in another town failed him on a service installation. He drove two grounds and then took one cable from each rod back to the service neutral bar with no wire between the two. The inspector told him to take one wire to one rod passing it thru the clamp and then onto the second rod. The inspector claimed the contractors way violated the rule about grounds being continuous. I have talked to three other inspectors and they agree with me that there is nothing wrong with what the contractor did. An unusual method to be sure but we feel he was in compliance. We invite your comments.

 

[sparky_magoo]

250.64 (3) states that the bonding jumpers from the grounding electrodes shall be permitted to be connected to a busbar. I believe you are correct.

 

[George Stolz]

Technically, I believe this is two GEC's, not a GEC and a jumper.

Legal no matter how you name them. 8)

 

[davidv]

as per 250.52 B all it needs is to be "effectively bonded." no specific description on the code so related sections will govern : code sized GEC, code approved connections, physically secured from damage, less than 25ohms resistance (test point at the busbar)
Assuming the above are met then the installation is valid, have a written explanation concurred by a PE to satisfy the Inspector.
But If I were the inspector I will pass it only if certified by a PE.
Interconnecting the GE's is a method of lowering the resistance, minimizing potential difference between GEs and effectively distributing the dissipation of fault current. Tried & tested. NEC is only a minimum requirement. it is not always the most efficient best practice.
My interest is that, are wiring Permits issued without an electrical plan signed and sealed by a PE ? why are contractors allowed to decide on this, its the designers job to provide the details for this, if field details are proposed then Designers recommending approval is needed, this would not happen if the contractor employs the service of a PE for its projects.
Is this the prevailing practice on this area?
If I were the client, regardless of contract,I will nail the contractor for not giving the best practice available, whats the cost of interconnecting wire and clamps and the digging ? peanuts! theres always excess phase wires for every job. its not worth the delay in energization.

davidv

 

[bphgravity]

As an inspector, you can't require something that is not code or procedure of the administrative policies. The original question is completely compliant and they don't need permission of a PE to design the electrial system as they seem fit, unless specified on the approved plans.

There is no evidence that running a GEC to one electrode and then bonding each other electrode to it is any better or more effective verses running to each electrode individually.

 

[Paul M]

Unless the size of the GEC is reduced for parrallel paths, the resistance would be half having the GECs paralleled, seems like a good thing to me.

 

[davidv]

as I stated if conditions are met the installation is compliant. to convince the inspector perhaps a PE can help.
Are Inspectors not allowed to establish a local standard by adopting from other authoritative organizations, (may be a long process) coz for me the Code is only a minimum for safety,not always for effectivity & efficiency.

Also can u describe the practice there coz in our region Electrical plans (even for less than 10kw) sign by a PE is required including the license of the person in charge of install'n before a wiring permit is issued. then the inspections, cetificate, utility power.

Its already a standard practice for many grounding installations if there were no advantage then would have been abandoned long ago.

 

[Paul M]

davidv, I hope I never have to go into business in your area whereever that may be. If I had to get a PE involved everytime I wanted to do a job and get his blessing, I'd find a different trade.

 

[peter d]

Are Inspectors not allowed to establish a local standard by adopting from other authoritative organizations, (may be a long process) coz for me the Code is only a minimum for safety,not always for effectivity & efficiency.

No, you are not allowed to enforce additional rules unless they are added as local ammendements to the NEC and written into law.

The NEC is solely concerned with safety and nothing else. It is your job to ensure that an installation is safe. If the installer and/or customer wants to exceed the NEC to proivde a more efficient installation, that is their choice, but you can't force them to do it.

 

[eprice]

I'd just like to point out that 250.64(F):

A grounding electrode conductor shall be permitted to be run to any convenient grounding electrode available in the grounding electrode system, or to one or more grounding electrode(s) infividually....

specifically permits the installation described in the opening post.

 

[davidv]

PaulM, our region is haven for PE's and Inspectors makes guys like me to practice elsewhere on the planet.
Thanks Eprice , its just when the codes says (A to F) like read A to B only a bad habit I admit.
Anyway, the practice in USA is still not clear to me.Whats the job of PE's there, is there a KVA limitation or something.Why do the Inspectors disagree with opinions, are electrical laws differ from each states?

 

[iwire]

Its already a standard practice for many grounding installations if there were no advantage then would have been abandoned long ago.

Maybe or perhaps many people simply accept that what we have always done is as good as it gets.