Grounding Conductor, where is it?

[Parkview56]

I have come upon an installation that I question if it is code compliant.
There is a multiple gang meter enclosure (3),with two(2), 200A services and one (1), 100A service. The source voltage is 120/208, 3PH,4wire. All of the grounding electrodes are bonded at the meter enclosure to a common bus that is bonded to the system grounded conductor. At the service disconnecting means there are three(3) phase conductors and the grounded conductor. Shouldn't there be an equipment bonding jumper from the meter enclosure? The raceway system is PVC.

 

[roger]

I have come upon an installation that I question if it is code compliant.
There is a multiple gang meter enclosure (3),with two(2), 200A services and one (1), 100A service. The source voltage is 120/208, 3PH,4wire. All of the grounding electrodes are bonded at the meter enclosure to a common bus that is bonded to the system grounded conductor. At the service disconnecting means there are three(3) phase conductors and the grounded conductor. Shouldn't there be an equipment bonding jumper from the meter enclosure? The raceway system is PVC.

There is no need for an EGC to the service disconnect, the main bonding jumper is where the neutral block in the meter enclosure is attached to the meter enclosure, the neutral conductor from this point is the fault clearing conductor ahead of the service disconnect.

Roger

 

[Volta]

Welcome to the forum!

There are a million details to grounding, but you can think of the service disconnect(s) as the place that it changes.



For any non-paralleled service, on the line side there is only one grounded conductor. We can connect it to the ground aywhere up to the service disconnect. That is doing all the bonding needed between those two enclosures.

On a grounded service we have the Grounded Conductor (GC) connected to the Equipment Grounding Conductor(s) (EGC), via a Main Bonding Jumper (MBJ).

The Grounding Electrode System (GES), which is connected together by Bonding Jumper(s) (BJ), is connected to the GC with a Grounding Electrode Conductor (GEC).



The phrase Equipment Bonding Jumper (EBJ) might be used a couple different ways. but that isn't used as much for most "regular" services, in my opinion.

 

[Parkview56]

Maybe I should rephrase the question. The service disconnecting means is a 200A MCB in the loadcenter. Where is the equipment bonding conductor or is one even needed?

 

[roger]

Maybe I should rephrase the question. The service disconnecting means is a 200A MCB in the loadcenter. Where is the equipment bonding conductor or is one even needed?

Not needed if it is done in the meter enclosure.

Roger

 

[Dennis Alwon]

Maybe I should rephrase the question. The service disconnecting means is a 200A MCB in the loadcenter. Where is the equipment bonding conductor or is one even needed?

Basically the meter pan is bonded thru the neutral since the neutral is diectly connected to the can. The same should be true in the service disconnect usually thru a bonding screw or strap. Once you leave the service disconnect then an egc is required.

 

[david luchini]

Maybe I should rephrase the question. The service disconnecting means is a 200A MCB in the loadcenter. Where is the equipment bonding conductor or is one even needed?

Not needed if it is done in the meter enclosure.

Roger

I disagree (sort of.) I think a Main (not equipment) Bonding Jumper is required to connect the equipment grounding conductors and the service disconnect enclosure to the grounded conductor within the enclosure for each service disconnect (250.24(B).) That would require a bond within the load center.

In addition, 250.24(C) requires that the grounded conductor be connected to the service disconnecting means enclosure.

I think 240.24(D) would also require a grounding electrode conductor from the service equipment enclosure to the grounding electrode.

 

[K8MHZ]

I disagree (sort of.) I think a Main (not equipment) Bonding Jumper is required to connect the equipment grounding conductors and the service disconnect enclosure to the grounded conductor within the enclosure for each service disconnect (250.24(B).) That would require a bond within the load center.

In addition, 250.24(C) requires that the grounded conductor be connected to the service disconnecting means enclosure.

I think 240.24(D) would also require a grounding electrode conductor from the service equipment enclosure to the grounding electrode.

The connection must also be accessible. Their is no concrete consensus as to whether or not a connection in a meter socket is accessible or not. I say 'not' and so does pretty much everyone in Michigan. Consumer's Power actually forbids the practice, other POCO's may as well.

 

[roger]

I disagree (sort of.) I think a Main (not equipment) Bonding Jumper is required to connect the equipment grounding conductors and the service disconnect enclosure to the grounded conductor within the enclosure for each service disconnect (250.24(B).) That would require a bond within the load center.

In addition, 250.24(C) requires that the grounded conductor be connected to the service disconnecting means enclosure.

I think 240.24(D) would also require a grounding electrode conductor from the service equipment enclosure to the grounding electrode.

I agree, I was still fixated on the GEC connection.

Roger

 

[roger]

The connection must also be accessible. Their is no concrete consensus as to whether or not a connection in a meter socket is accessible or not. I say 'not' and so does pretty much everyone in Michigan. Consumer's Power actually forbids the practice, other POCO's may as well.

That's fine for Michigan, many other areas don't have a problem with it.

Please tell me why Michigan thinks a GEC connection would need accessibility more so than the other connections do?

Also, does Michigan have a lot of problems with GEC connections and what are the symptons of these problems?

Roger

 

[Dennis Alwon]

That's fine for Michigan, many other areas don't have a problem with it.

Please tell me why Michigan thinks a GEC connection would need accessibility more so than the other connections do?

Also, does Michigan have a lot of problems with GEC connections and what are the symptons of these problems?

Roger

My sentiments exactly. Are the service conductors accessible? Guess you can't land them in the meter base either...

 

[roger]

My sentiments exactly. Are the service conductors accessible? Guess you can't land them in the meter base either...

That's right, there will be no more electric service to anyone that has a meter installed on their building. :grin:

Roger

 

[K8MHZ]

That's fine for Michigan, many other areas don't have a problem with it.

Please tell me why Michigan thinks a GEC connection would need accessibility more so than the other connections do?

Also, does Michigan have a lot of problems with GEC connections and what are the symptons of these problems?

Roger

I don't have the answer to why the policy exists, and I also am aware that connections are made in the meter socket in other locales.

Actually, the part of Michigan that I live in has very poor soil conductivity and the entire connection to the earth could go away practically un-noticed. An inspector friend of mine did some testing and found that a single 8 foot rod had a resistance of 1300 ohms. We live pretty much on a sand dune.

On edit: I have asked several inspector types why we can't use the factory installed GEC terminal that is inside all the Milbank meter sockets we install and they all said it was a POCO rule. Odd, since we get the sockets from the POCO.....

 

[roger]

Actually, the part of Michigan that I live in has very poor soil conductivity and the entire connection to the earth could go away practically un-noticed.

But that wouldn't have anything to do with where the GEC connection is made

An inspector friend of mine did some testing and found that a single 8 foot rod had a resistance of 1300 ohms. We live pretty much on a sand dune.

Unless we are only using one rod, the NEC doesn't have a minimum resistance for the GES 1300 ohms would be fine for most installations.

I have found that many POCO's really have no clue as to what we are doing with our earthing, they are happy to have us take a HV or lightning event into a structure.

Roger

 

[tom baker]

Perhaps we are all missing the point of the GEC connection be accessible.
I recall reading a long time ago the GEC had to be accessible to allow it to be disconnected for electric pipe thawing.
From the instructions for the Electric Icebreaker
"DISCONNECT ALL GROUNDS AT EITHER END OF THE ELECTRICAL WIRING SYSTEM."

 

[A/A Fuel GTX]

I say the GEC IS accessible in a meter section that has a POCO seal. Accessible, yes.......readily accessible...no but accessible is all that's required by the NEC. My POCO, Xcel Energy will not allow us to land the GEC in any of their wiring spaces no matter how large the compartment may be. I can see their point in the older meter sockets that barely have enough room for the service entrance conductors but the new meter sockets and MCB enclosures are more than adequate to land the GEC in. I brought this goofy requirement up the the Xcel meter shop and was told the main reason for not allowing the GEC in sealed compartments is that they don't want to go out to trouble calls where lights are flickering and such and have to check the integrity of the GEC termination. I told them that the GEC connection has absolutely nothing to do with those type of problems and their reasoning is flawed. I explained the purpose of the GEC and actually got their attention. Im sure the point will fall on deaf ears however. I put POCO's and the government on the same plane and even if there are regulations that make no sense, getting them changed are practically impossible.

 

[hurk27]

I don't have the answer to why the policy exists, and I also am aware that connections are made in the meter socket in other locales.

Actually, the part of Michigan that I live in has very poor soil conductivity and the entire connection to the earth could go away practically un-noticed. An inspector friend of mine did some testing and found that a single 8 foot rod had a resistance of 1300 ohms. We live pretty much on a sand dune.

On edit: I have asked several inspector types why we can't use the factory installed GEC terminal that is inside all the Milbank meter sockets we install and they all said it was a POCO rule. Odd, since we get the sockets from the POCO.....

H'mmmm how close are ya to the Indiana state line, we have allot of sand here too:grin: