grounding conductor dilemma

[elecon]

We recently installed a 200amp service to an existing residence with 3-3/0 and 1-#4 copper conductors from the meter base to the main panel. The #4 was terminated at the bonded neutral bar in the main panel. We also installed from the main panel bonded neutral bar 1-#4 to the incoming copper water pipe and 1-#4 to the new outside 8' ground rod. The inspector wants us to install a continuos #4 from the ground rod thru the meter base to the main panel bonded neutral bar. He accepts the #4 to the water pipe. Any thoughts on this?

[ September 13, 2005, 01:53 PM: Message edited by: elecon ]

 

[bphgravity]

Re: grounding conductor dilemma

Why are you installing 4-wire between the meter and main?

250.24(A)(1) permits the GEC's to be connected at any accessible point from the service point to the grounded terminal in the main disconnect panel. There is no reason to require the conductor from the ground rod to continue through to the main.

In this area, we would require 2 rods with the water pipe. The rods would only require #6.

 

[augie47]

Re: grounding conductor dilemma

Seems no one more knowledgable will bite, so I will.

3-3/0 and 1-#4 copper conductors from the meter base to the main panel. The #4 was terminated at the bonded neutral bar in the main panel.

1st off, assuming this is a single phase service, amd assuming the #4 was terminated at the same point as your 3/0 in the meter base, I'd have a problem with this due to paralleling of conductors.,,,not the question you asked, but a point.

1-#4 to the incoming copper water pipe and 1-#4 to the new outside 8' ground rod.

are we talking two seperate conductors, one to the rod, one to the pipe, each from the bonded neutral ?
I believe I'm missimg something in understanding his requirement.
In our jurisdaiction, the rod #4 would have run from he meter base, but I know that varies from one area to another often due to POCO requirements.
More details, please.

 

[elecon]

Re: grounding conductor dilemma

This is a single phase system. There are 2 seperate #4's one to the ground rod and one to the water pipe. They both land in the main panel. The jurisdiction requires a wire to be installed from the meter base to the ground bar in the main panel sized in accordance with 250.66. We have conflicting interpretations on how to ground the meter base and where that conductor should land.

 

[augie47]

Re: grounding conductor dilemma

O.K., If your neutral bar is bonded, I still have a problem with the #4 and 3/0 parallel....but...back to your question...
from what you say, I have no problem with the gec to water and rod the way you installed it...I'd have to have his reasoning, maybe 90-4. or, of course, I'm overlooking something, but I see no reason for the #4 to pass thru the meter base enroute to another termination point, in fact, if your service conduit to your panel happened to be steel we would be opening up another whole can of worms..

 

[elecon]

Re: grounding conductor dilemma

The installation is pvc and the neutral is bonded. 90-4 may be the answer, but not what Im looking for. How would you handle grounding the meter base? And is 250-24(a)(1) the answer to give him for installing a #4 from the meter base to the ground rod?

 

[roger]

Re: grounding conductor dilemma

The meter base would already be bonded to the GEC via the neutral conductor connection to the factory mounting of the neutral/grounding bar in the meter base.

As already stated, if an additional conductor (the #4) is run from this point to the GEC connection in the panel your inspector is instructing you to install a parallel conductor that is totally wrong.

In the following diagrams the GEC is shown in the meter socket but for your installation imagine it in the panel and the same scenario exists.

In the first diagram you can see current flowing on the #4 conductor that the inspector is asking you to install and in my opinion would be violating 310.4.

The second diagram would be correct.

Roger

[ September 13, 2005, 05:53 PM: Message edited by: roger ]

 

[hurk27]

Re: grounding conductor dilemma

The answer is in 250.142(A):

A) Supply-Side Equipment. A grounded circuit conductor shall be permitted to ground non?current-carrying metal parts of equipment, raceways, and other enclosures at any of the following locations:

(1) On the supply side or within the enclosure of the ac service-disconnecting means

(2) On the supply side or within the enclosure of the main disconnecting means for separate buildings as provided in 250.32(B)

Which allows this And is backed up by 250.92(B)(1):

B) Method of Bonding at the Service. 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

It is not required to run a bonding conductor between the meter and service disconnect or main panel, as this would be a violation of 310.4

Keep in mind that if you run a grounding electrode conductor through any raceway or box even the meter cabinet it is required to bond the raceways containing the GEC together as per 250.92(A)(3)

 

[LarryFine]

Re: grounding conductor dilemma

In simple English, Elecon, it is proper to land the water-pipe and driven grounds separately to the main-panel's neutral bus, unless there is a disconnect at the meter, in which case that's where they should land.

There is no purpose in running a separate conductor from the meter base to the panel, again unless there is a disconnect at the meter, because the neutral is bonded to both enclosures, the meter and the panel.

I would ask the inspector with which NEC article he is saying your installation has failed to comply.

 

[stud696981]

Re: grounding conductor dilemma

One thing to add, ground rod(s) only require a #6 cu wire. The water pipe though has to be sized according to the phase conductors, so in this case it would be a #4.

 

[elecon]

Re: grounding conductor dilemma

The inspector is saying that the lug in the meter base is for installing a parallel conductor to the main panel and not for connection to a ground rod. He wont let us have 2 conductors connected to the ground rod. ie: 1 from the main panel and 1 from the meter base.

 

[stud696981]

Re: grounding conductor dilemma

The inspector is wrong. This would create a parallel path for current to flow on the neutral conductor.

 

[BruceH]

Re: grounding conductor dilemma

Around here (upstate NY) you would not attach the grounding electrode conductor to the meter socket, it would terminate in the main panel. This would be a poco requirement, they strictly forbid terminating the gec at the meter socket. The meter socket is bonded as well as the main panel.Also, #4 is required for a 200 amp service to any ground rods, not #6, again this is only pertaining to my location, not nec. Not much help I know, just a fyi.

 

[roger]

Re: grounding conductor dilemma

Originally posted by elecon:
The inspector is saying that the lug in the meter base is for installing a parallel conductor to the main panel and not for connection to a ground rod.

One more time, the inspector is wrong.

Roger

[ September 14, 2005, 11:54 AM: Message edited by: roger ]

 

[elecon]

Re: grounding conductor dilemma

Thanks for your help. In my situation what would the lug on the meter base be used for if we already have a GEC from the main panels bonded neutral to a water pipe and a supplemental electrode from the main panels bonded neutral to a ground rod per 250.53(D)(2).

 

[roger]

Re: grounding conductor dilemma

Elecon, it would just be left empty (unused)

Look at the diagram below, the Electrodes can be bonded together with jumpers, there is no reason to bring more than one connection to the Main panel or Meter can unless it is simply convenient for you as the installer.

Roger

 

[elecon]

Re: grounding conductor dilemma

Roger thanks for the help. Do you think a parallel conductor is formed if you take the GEC from the meter base to a ground rod and a GEC from the main panels bonded neutral to the same ground rod? We had another inspector in the same municipality require this. In addition he required a GEC from the main panels bonded neutral to the water pipe. We argued against installing a GEC from the panel to the ground rod since we already had one.

 

[roger]

Re: grounding conductor dilemma

Originally posted by elecon:
Roger thanks for the help. Do you think a parallel conductor is formed if you take the GEC from the meter base to a ground rod and a GEC from the main panels bonded neutral to the same ground rod? We had another inspector in the same municipality require this. In addition he required a GEC from the main panels bonded neutral to the water pipe. We argued against installing a GEC from the panel to the ground rod since we already had one.

Elecon, you are welcome.

If you took a GEC from both locations they would indeed be in parallel with the Grounded (neutral) Conductor.

These inspectors need to take some of Mike Holt's courses on Grounding and Bonding, they undoubtedly are confused on the issue(s)

Roger

 

[ZERO SEQUENCE CURRENT]

Re: grounding conductor dilemma

The inspector wants to see the grounding conductor coming out of the meter base and the power company too ,so that they will no that there crap is grounded.The inspector can assume the service enclosure is grouded and bonded to the meter can if you use metal conduit,but if you use pvc conduit you have to run a bonding jumper.Since the neutral and ground are bonded in the meter can and the service enclosure you'd create parallel paths for the neutral.THe ground is supposed to carry no current during normal operation.

 

[roger]

Re: grounding conductor dilemma

Originally posted by ZERO SEQUENCE CURRENT:
The inspector wants to see the grounding conductor coming out of the meter base and the power company too ,so that they will no that there crap is grounded.The inspector can assume the service enclosure is grouded and bonded to the meter can if you use metal conduit,but if you use pvc conduit you have to run a bonding jumper.Since the neutral and ground are bonded in the meter can and the service enclosure you'd create parallel paths for the neutral.THe ground is supposed to carry no current during normal operation.

Exactly what are you trying to say?

Roger