CURRENT GOING DOWN GROUND ROD HELP!!!!

[kwired]

Since transformer ownership changed 4yrs ago, it's not clear to me where your service point is now.

If it switched to the supply side of the transformers, your new equipment installation may not be a service.

Grounding and bonding requirements for feeders and SDS for whatever your current code cycle is would be more appropriate than those for a service.

We don't let anyone do work on energized equipment (other than troubleshooting, voltage testing or non-contact inspections with appropriate PPE) If if the work requires use of a tool on energized conductors or circuit parts, we shut it down first.



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It does get clouded a bit in a situation like described here. The campus owns the transformers, but POCO is contracted to maintain them. This still kind of makes it POCO controlled equipment even though they do bill the customer for most anything done to it. It may come down to more technical details in contracts or service agreements to determine just what the service point actually is.

But if transformers are indeed on customer side of service point then the service equipment is going to be medium voltage equipment - if such service equipment doesn't exist we have an even bigger can of worms - plus now OP's building is served by two feeders instead of two services - which is a little more clear of a violation then if it were two services - maybe, there is another current thread debating multiple feeders and services to a building and whether it is allowed.

There is no bonding jumper at the generator where this CT is. Cant bond it here because the neutral is not switched. Yeah about the six disconnects i agree, just a poor way of doing things. I cant isolate the service wires to make any changes. I really don't like this method of wiring.

You have alternate path somewhere on load side of this CT or you would not lose any current before it reaches the CT causing the imbalance that makes it trip. Maybe an inadvertent neutral - ground bond somewhere? Doesn't have to be improperly installed jumper, just a skinned neutral touching a grounded object could do it. If this is serving a lot of data equipment - don't overlook someone thinking a ground rod was or a bond to a water pipe or building steel isn't a point of crossover causing such problems, and someone though this was a good solution to a problem at some point.

 

[Smart $]

It does get clouded a bit in a situation like described here. The campus owns the transformers, but POCO is contracted to maintain them. This still kind of makes it POCO controlled equipment even though they do bill the customer for most anything done to it. It may come down to more technical details in contracts or service agreements to determine just what the service point actually is.

But if transformers are indeed on customer side of service point then the service equipment is going to be medium voltage equipment - if such service equipment doesn't exist we have an even bigger can of worms - plus now OP's building is served by two feeders instead of two services - which is a little more clear of a violation then if it were two services - maybe, there is another current thread debating multiple feeders and services to a building and whether it is allowed.

...

Change of ownership typically does not change the installation from being service(s) to SDS(s)... just the service point is relocated.

 

[jtinge]

Change of ownership typically does not change the installation from being service(s) to SDS(s)... just the service point is relocated.

I would agree for existing service entrance equipment but the OP said the transformers changed ownership 4yrs ago. The new equipment was just installed. I think one could make a case that the new equipment doesn't meet the definition of service.


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[Smart $]

I would agree for existing service entrance equipment but the OP said the transformers changed ownership 4yrs ago. The new equipment was just installed. I think one could make a case that the new equipment doesn't meet the definition of service.

That's a reasonable point of contention. The general premise for debate: what is different between a service where POCO owns transformer and a service where the consumer owns the transformer (if such a service is permitted)? Say you have a premises supply with pad transformer on consumer's property. In one case, the POCO owns the transformer. In another, the consumer owns the transformer. Does the latter automatically mean, if installed under current Code, that the service disconnecting means must be on the primary side or the transformer?

I'm aware of several such instances here in Ohio, and the POCO still 'dictates' the transformer requirements, connections, minimal grounding, etc.... and there is no service disconnecting means on the primary side, just the POCO cut-outs.

Now if we look at 230.81 we can see a power transformer is not listed. So are all these instances non-compliant???

 

[jtinge]

I think this has been debated at nausium on previous threads regarding campus distribution systems supplying buildings vs utilities.


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[Smart $]

I think this has been debated at nausium on previous threads regarding campus distribution systems supplying buildings vs utilities.

Perhaps... but with you at 168 posts I'm thinking you didn't weigh in. Regardless, it appears you don't care to share an opinion here.

FWIW, there is no requirement in the NEC that a transformer be connected as an SDS... and with the primary ground (which is typically the primary grounded conductor where the distribution system is wye) connected to the secondary neutral, the transformers in this case would not be SDS... and the NEC only has two scenarios: service and SDS. Would that require the new transformer to be wired as SDS, or can it be non-SDS and still considered a service. It has to be one or the other. Then if it is wired as an SDS, we have a feeder and a service supplying the same building... and if you lurk the forum much, you know there was a fairly exhaustive recent thread debating the compliance of that scenario.

As it stands, I'm not going to debate either issue. I see it as safe either way. :happyyes:

 

[kwired]

Change of ownership typically does not change the installation from being service(s) to SDS(s)... just the service point is relocated.

I agree, I think.

Around here on the rural systems it is common for POCO to install and even provide some maintenance to the equipment they install on a pole at customer locations. This typically includes raceway up the pole, meter socket, and a disconnect, or a meter/main for most 100-200 amp single phase services. But they actually sell this equipment to customer - usually including the pole it is mounted on. If you upgrade from say a 200 to a 400 amp service, your old equipment they take down is yours, they leave it there because you paid for it at one time. But service point is still considered to be load terminals of that equipment because it is POCO provided and maintained, and may not even meet NEC in some instances, some of the equipment they do install is not listed.

If a campus decides to take ownership of transformers and other gear, yet contract the POCO to still maintain it/make new installs on that part of the distribution it may save them some cost from POCO over time, but they are still going to have to pay for maintenance and repairs as it comes up.

 

[jtinge]

Perhaps... but with you at 168 posts I'm thinking you didn't weigh in. Regardless, it appears you don't care to share an opinion here.

There are a lot of really smart people that post here, and I am happy to learn from those that are smarter than me. I try to only post when I think I can make a positive contribution to the discussion.

FWIW, there is no requirement in the NEC that a transformer be connected as an SDS... and with the primary ground (which is typically the primary grounded conductor where the distribution system is wye) connected to the secondary neutral, the transformers in this case would not be SDS... and the NEC only has two scenarios: service and SDS. Would that require the new transformer to be wired as SDS, or can it be non-SDS and still considered a service. It has to be one or the other. Then if it is wired as an SDS, we have a feeder and a service supplying the same building... and if you lurk the forum much, you know there was a fairly exhaustive recent thread debating the compliance of that scenario.

I agree that if the transformer was installed by the POCO as you described and it changed ownership as was described in the OP, I would probably still treat it as a service because from a connection, bonding and grounding stand point nothing has changed by changing the service point location.

I was trying to make the point that from a definition stand point, (post 1999 NEC definition of service) new building service equipment not fed by a utility would not be a service. But continuing to treat the OP described installation as service is not a difficult stretch for me.

But other installations, where the customer owns the distribution system or the outdoor unit substation(s) that provides power to the building, have also been treated as services. I believe because the NEC permitted this up until the definition of service changed in 1999. Often these distribution systems may or may not have primary grounded conductor. I know in our case, we own the distribution system, the primary MV distribution substations, and the multiple outdoor unit substations at each building that in the past were treated as the service to the buildings.

The NEC clearly makes the point that this type of system can no longer be described as a service because the service point is at the main substation and not in close proximity to each building. So it is not a typically for us to have three or four outdoor unit substations, with transformers ranging from 500kVA to 1500kVA as the supply of power to our buildings. While everyone calls them the service to the buildings, they technically don't meet the definition of service.

 

[kwired]

There are a lot of really smart people that post here, and I am happy to learn from those that are smarter than me. I try to only post when I think I can make a positive contribution to the discussion.

I tend to be one of those that says what I think, and let others correct me if I am wrong. I usually learn more that way then just assuming something I see is correct. I have stated my opinion and then had my opinion changed several times here, as well as pointing out things to others and changing their opinion. If you can get several people to say they agree with something, then that opinion is usually pretty much something true in nature.

 

[Smart $]

I agree, I think.

...

There are a lot of really smart people that post here, and I am happy to learn from those that are smarter than me. ...

I tend to be one of those that says what I think...

I think we're getting a bit off topic here. If we take a strict Code-interpretation approach, both existing and new building supplies would have to be revise to compliant. For one, they don't have different characteristics enough to warrant two transformer with the same output voltage and configuration. Additionally, a service disconnecting means would be required on the primary side of a transformer, and the transformer would require at the very least primary OCPD. I believe I'll let someone else concern themselves with compliance on that issue. :happyyes:

Getting back to the OP issue, I believe in addition to the recommendations I presented earlier, the primary grounded/-ing to secondary grounded/-ing bonds would have to be removed to mitigate parallel neutral current pathways.

 

[jtinge]

Getting back to the OP issue, I believe in addition to the recommendations I presented earlier, the primary grounded/-ing to secondary grounded/-ing bonds would have to be removed to mitigate parallel neutral current pathways.

I would agree with that assessment.


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[5 S electric]

I think we're getting a bit off topic here. If we take a strict Code-interpretation approach, both existing and new building supplies would have to be revise to compliant. For one, they don't have different characteristics enough to warrant two transformer with the same output voltage and configuration. Additionally, a service disconnecting means would be required on the primary side of a transformer, and the transformer would require at the very least primary OCPD. I believe I'll let someone else concern themselves with compliance on that issue. :happyyes:

Getting back to the OP issue, I believe in addition to the recommendations I presented earlier, the primary grounded/-ing to secondary grounded/-ing bonds would have to be removed to mitigate parallel neutral current pathways.

I also agree. The problem is that my transformer and service disconnect share the same GEC. Even though i didn't pull a ground wire from my transformer the GEC is all the same therefore current is also following this path. I have two bonds. I disconnected the bond in the service disconnect and all of the power started flowing down the neutral. I re installed the bond for now. Going to ask my inspector if i can pull a ground wire from the transformer to the disconnect and remove the bond at the service disconnect. So the only place it will be bonded is at the transformer. If he don't go for that i will have to do what one of you guys said, drive more ground rods at the transformer and take off and isolate my existing GEC.

Thanks you guys are a ton of help!!!

 

[kwired]

I also agree. The problem is that my transformer and service disconnect share the same GEC. Even though i didn't pull a ground wire from my transformer the GEC is all the same therefore current is also following this path. I have two bonds. I disconnected the bond in the service disconnect and all of the power started flowing down the neutral. I re installed the bond for now. Going to ask my inspector if i can pull a ground wire from the transformer to the disconnect and remove the bond at the service disconnect. So the only place it will be bonded is at the transformer. If he don't go for that i will have to do what one of you guys said, drive more ground rods at the transformer and take off and isolate my existing GEC.

Thanks you guys are a ton of help!!!

All services, separately derived systems, etc. must all be bonded together and have a common grounding electrode system, so I don't really see what you are getting at here.

 

[templdl]

Bravo, I was thinking the same thing, but there is no thank's button to hit so I will use this-

Thanks,
That is the first thing that I would sort out.

 

[Smart $]

All services, separately derived systems, etc. must all be bonded together and have a common grounding electrode system, so I don't really see what you are getting at here.

He's attempting to mitigate neutral current on the GES.

 

[GoldDigger]

Which sometimes just needs to be accepted, when it is the result of service or SDS geometry....
But in this case, it would seem to be more related to a missing or undersized bond or EGC than to the use of multiple electrodes.

 

[Smart $]

Which sometimes just needs to be accepted, when it is the result of service or SDS geometry....
But in this case, it would seem to be more related to a missing or undersized bond or EGC than to the use of multiple electrodes.

Actually in this case, I believe its a result of two to several too many bonds. :blink:

 

[GoldDigger]

But unless the ground electrode resistance is unusually low, the majority of the objectionable neutral current flowing in the GES should only be flowing in EGCs rather than through the earth.
I agree that normal neutral current should not be seen on the EGC either. But why is it flowing through the GEC into the electrode unless the EGC path is also high resistance?

 

[Smart $]

But unless the ground electrode resistance is unusually low, the majority of the objectionable neutral current flowing in the GES should only be flowing in EGCs rather than through the earth.
I agree that normal neutral current should not be seen on the EGC either. But why is it flowing through the GEC into the electrode unless the EGC path is also high resistance?

Its not flowing into and through earth. It flowing through a multi-tapped GEC.

 

[GoldDigger]

Its not flowing into and through earth. It flowing through a multi-tapped GEC.

So basically the thread title is incorrect?
That makes this whole discussion out of scope and therefore unenforceable?
:angel: