I have a 320 meter base and off of it 2 200 amp disconnects. Off of each disconnect I have 2 ground rods. For a total of 4 ground rods. Each set of ground rods is connected to #6 bare wire. Do I have to have ground rods connected from disconnect through ground rods through other set of ground rods back to other disconnect. I just failed an inspection because I didn't. But I have done this before and always passed.
NEC
- Thread starter atbenson
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: NEC
It sounds like you have two separate services, perhaps to two different buildings. I think each disconnect represents a separate entity, and that each should be handled separately. It does not matter if there is another service disconnect in the area, and the fact that two disconnects come from the same meter does not change the situation.
Can you get the Inspector to cite an NEC article as the basis for failing your installation?
It sounds like you have two separate services, perhaps to two different buildings. I think each disconnect represents a separate entity, and that each should be handled separately. It does not matter if there is another service disconnect in the area, and the fact that two disconnects come from the same meter does not change the situation.
Can you get the Inspector to cite an NEC article as the basis for failing your installation?
Re: NEC
I don't see that you would need 4 rods, 2 would suffice. As for the loop, if you are in NY state, then I would say YES. We are required (at least in my area) if using rods, to go from grounding terminal in disconnect to first rod, then to second rod, then back to grounding terminal all with one unbroken conductor.
This is under the presumption that this is for one building being served. Edit to clarify that.
[ December 20, 2005, 10:39 AM: Message edited by: BruceH ]
I don't see that you would need 4 rods, 2 would suffice. As for the loop, if you are in NY state, then I would say YES. We are required (at least in my area) if using rods, to go from grounding terminal in disconnect to first rod, then to second rod, then back to grounding terminal all with one unbroken conductor.
This is under the presumption that this is for one building being served. Edit to clarify that.
[ December 20, 2005, 10:39 AM: Message edited by: BruceH ]
bphgravity
Senior Member
- Location
- Florida
Re: NEC
You are only required to ground A service once. 250.24(A)(1) specifies where this grounding can be accomplished. Otherwise, you are exceeding the requirements of the NEC.
You are only required to ground A service once. 250.24(A)(1) specifies where this grounding can be accomplished. Otherwise, you are exceeding the requirements of the NEC.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: NEC
I think the point here is that the OP is being required to go from one service to its pair of ground rods, and then to the pair of ground rods for the other service, and then back to the second service. I believe that is not required, and I think it might even be the wrong thing to do. I would not want my house's electrical system to be impacted by any kind of fault in my neighbor's system. If there is dirt separating his ground rods from mine, then I would consider that adequate isolation. If his ground rods are bonded to my ground rods, our systems would no be independent. I'm not sure if anything bad could ever happen, but I am sure I would not like the situation.
bphgravity
Senior Member
- Location
- Florida
Re: NEC
Why not just terminate the GEC to the grounded conductor in the meter enclosure?
Why not just terminate the GEC to the grounded conductor in the meter enclosure?
Re: NEC
http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=11;t=008947.
In this case, I see no reason for 4 ground rods (if the disconnects are grouped and not on seperate buildings). As questioned in my earlier post, to me, it is questionable if the 2nd disconnect even needs GE's if the 1st one is sized adequately for the service.
I would say if you had multiple ground rods, as grounding electrodes they would need to be bonded together, but one might take the stand that they are since both have GEC's back to the service.
I would think, two rods, with the GEC from one service disconnect would actually meet NEC. A GEC from the 2nd disconnect to the same rods might be in order.
charlie b, you are obviously far wiser than I am, and I try not to question you, but, in this case, I read that we may be talking about ONE service to a 320 amp socket and then two disconnects (common in this area). I posted a similair question at
http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=11;t=008947.
In this case, I see no reason for 4 ground rods (if the disconnects are grouped and not on seperate buildings). As questioned in my earlier post, to me, it is questionable if the 2nd disconnect even needs GE's if the 1st one is sized adequately for the service.
I would say if you had multiple ground rods, as grounding electrodes they would need to be bonded together, but one might take the stand that they are since both have GEC's back to the service.
I would think, two rods, with the GEC from one service disconnect would actually meet NEC. A GEC from the 2nd disconnect to the same rods might be in order.
allenwayne
Senior Member
Re: NEC
We are required to ground to the meter base and that is it .poco says no way will they hook up if attached at an inaccesabile panel (inside).
Now a gas bond can be from the meter ground or tagged off the panel.But there has to be a seperate connection for that
We are required to ground to the meter base and that is it .poco says no way will they hook up if attached at an inaccesabile panel (inside).
Now a gas bond can be from the meter ground or tagged off the panel.But there has to be a seperate connection for that
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Re: NEC
I recently did a similar service: 320a base and two 200a disconnects feeding two ML panels via SER. I ran a single, unbroken #6 from rod A, inside into disconnect A (bent into a U into lug), back out, into to dosconnect B, back out, and back outside to rod B.
It sounds to me that the simple fix for the original question would be to inter-connect the closer rod of each pair with a #6 with separate clamps. Rods are supposed to be tied together.
[ December 21, 2005, 12:10 AM: Message edited by: LarryFine ]
I recently did a similar service: 320a base and two 200a disconnects feeding two ML panels via SER. I ran a single, unbroken #6 from rod A, inside into disconnect A (bent into a U into lug), back out, into to dosconnect B, back out, and back outside to rod B.
It sounds to me that the simple fix for the original question would be to inter-connect the closer rod of each pair with a #6 with separate clamps. Rods are supposed to be tied together.
That's funny: we can't land the GEC in the meter because it's inaccessible. I wish we could; it's the ideal point, since it's already outside.
[ December 21, 2005, 12:10 AM: Message edited by: LarryFine ]
Re: NEC
Seems to me that 250.24(B) is written for this exact scenario:
(B) Grounded Conductor Brought to Service Equipment.
Where an ac system operating at less than 1000 volts is
grounded at any point, the grounded conductor(s) shall be
run to each service disconnecting means and shall be
bonded to each disconnecting means enclosure. The
grounded conductor(s) shall be installed in accordance with
250.24(B)(1) through (B)(3).
I agree with Bruce, if these disconnects feed the same building you only need the 2 rods. As far as the loop back to the grounding terminal, I've never heard of that requirement out here in the west.
Seems to me that 250.24(B) is written for this exact scenario:
(B) Grounded Conductor Brought to Service Equipment.
Where an ac system operating at less than 1000 volts is
grounded at any point, the grounded conductor(s) shall be
run to each service disconnecting means and shall be
bonded to each disconnecting means enclosure. The
grounded conductor(s) shall be installed in accordance with
250.24(B)(1) through (B)(3).
I agree with Bruce, if these disconnects feed the same building you only need the 2 rods. As far as the loop back to the grounding terminal, I've never heard of that requirement out here in the west.
- Location
- Windsor, CO NEC: 2023
- Occupation
- Hospital Master Electrician
Re: NEC
I'd take back two of the ground rods. It really sounds like they're on the same building.
I'd limit the problem Roger described by installing a busbar immediately below the disconnects, and then pull the GEC for the ground rod from there, and then attach the bonding jumper for the second rod to the first.
I'd take back two of the ground rods. It really sounds like they're on the same building.
I'd limit the problem Roger described by installing a busbar immediately below the disconnects, and then pull the GEC for the ground rod from there, and then attach the bonding jumper for the second rod to the first.
Re: NEC
Bravo George, that is one way to eliminate the loop, but there is nothing prohibiting it either.
IMO, if per the NEC, we can legally, (not sensibly) and in some cases even be required by inspectors to install a ring that will divide current proportionately between the grounded and grounding conductors, it would also be legal to use a ring in any circuit, or more specifically, any circuit conductor.
Roger
[ December 21, 2005, 10:20 PM: Message edited by: roger ]
Bravo George, that is one way to eliminate the loop, but there is nothing prohibiting it either.
IMO, if per the NEC, we can legally, (not sensibly) and in some cases even be required by inspectors to install a ring that will divide current proportionately between the grounded and grounding conductors, it would also be legal to use a ring in any circuit, or more specifically, any circuit conductor.
Roger
[ December 21, 2005, 10:20 PM: Message edited by: roger ]
pierre
Senior Member
- Location
- Westchester County, New York
Re: NEC
Take a look at 250.58 and 250.64(D)
Using the illustration in George's post, you would only need one more conductor to the second service disconnect from the detail below the panel.
BTW: Roger nice illustration
[ December 21, 2005, 11:39 PM: Message edited by: pierre ]
Take a look at 250.58 and 250.64(D)
Using the illustration in George's post, you would only need one more conductor to the second service disconnect from the detail below the panel.
BTW: Roger nice illustration
[ December 21, 2005, 11:39 PM: Message edited by: pierre ]
- Location
- Massachusetts
Re: NEC
And nice job George.
Ditto.Originally posted by pierre:
BTW: Roger nice illustration
And nice job George.
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