Utility CT Cabinet

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SparkyHC

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Southern New Jersey
I few days ago I was advised by a client that a Southern New Jersey Electrical Utility was not allowing their electrician to bond the neutrals of a 1200 ampere, 480V. service to the CT cabinet. The Electrical Inspector of course would not provide a cut-in card until the cabinet was grounded either by the neutrals or additional ground conductors. The final outcome of this is still undecided. My question to the members and readers here is, are there any other utilities not allowing supply side side neutrals to be terminated inside their CT Cabinets?
 
I would go up the chain of the utility until I found someone with a clue.


All our CT cabinets arrive with the neutral terminals directly bolted to the enclosure.
 
We have one power company over here that doesn't allow you to jump from the neutral bar in the CT can to the factory installed lug at the bottom of the can. What we do is take a bonding jumper out of the service disconnect and run it back to the CT can, lugged up to the outside of the can. Make sure you use a "wet location" type lug, DB, etc on the outside, our inspector likes to catch us on that one.
 
Cow said:
We have one power company over here that doesn't allow you to jump from the neutral bar in the CT can to the factory installed lug at the bottom of the can. What we do is take a bonding jumper out of the service disconnect and run it back to the CT can, lugged up to the outside of the can.
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I know you are doing what you have to but this is completely idiotic on the part of the power company.
 
SparkyHC said:
Yeah, I agree...
I spoke with someone upstairs and he said "this is the way we roll" and that they are doing it in the
interest of safety... the inspector and I don't agree with them.
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I would like to hear their explanation of why they feel this improves safety.

That said if this is on the POCO side of the Service Point, the inspector has no business even concerning himself with what is going on in that enclosure, the NEC doesn't apply here.
 
kwired said:
I would like to hear their explanation of why they feel this improves safety.

That said if this is on the POCO side of the Service Point, the inspector has no business even concerning himself with what is going on in that enclosure, the NEC doesn't apply here.
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Yes we realize that the CT cabinet is out of our jurisdiction, but you can't stand by and witness a potential hazard without trying to intervene...as fruitless as that has been so far.
 
I am a bit confused, The OP speaks of Bonding and landing supply ( line side Nuetrals) being landed in the CT compartment.
I have never heard of not landing the nuetral in the CT. Maybe your area has special CT compartments made.

I think what you are refering to is Bonding and grounding which is not done in the CT. That is done in the Main overcurrent section. Most PoCo's do not want bare wires in the CT other than the Factory Buss bars.
 
Sierrasparky said:
I am a bit confused, The OP speaks of Bonding and landing supply ( line side Nuetrals) being landed in the CT compartment.
I have never heard of not landing the nuetral in the CT. Maybe your area has special CT compartments made.

I think what you are refering to is Bonding and grounding which is not done in the CT. That is done in the Main overcurrent section. Most PoCo's do not want bare wires in the CT other than the Factory Buss bars.
Click to expand...

Around here our CT cabinets in the gear have a mechanical lug on the ground buss for the GEC. Right next to it is usually a piece of buss (Main bonding jumper) that swings over and bolts to the utilities neutral buss where all their service neutrals are. Very similar among all manufacturers, square D, Siemens, GE.....
 
Sierrasparky said:
I am a bit confused, The OP speaks of Bonding and landing supply ( line side Nuetrals) being landed in the CT compartment.
I have never heard of not landing the nuetral in the CT. Maybe your area has special CT compartments made.

I think what you are referring to is Bonding and grounding which is not done in the CT. That is done in the Main overcurrent section. Most PoCo's do not want bare wires in the CT other than the Factory Buss bars.
Click to expand...

In New Jersey we have three Pocos. Since the day I started we have been landing the supply side grounded conductors or neutrals in the CT cabinets of all the Pocos. This directive "not" to allow termination of the neutrals in the CT cabinet is new as far as I am aware. Why, is only speculation at this point. To comply with their directive at this particular project, the neutrals will pass through the CT cabinet unbroken, travel another 125 feet to the service gear where they are bonded to ground with the GEC. What bothers me is that they are asking for grounding conductors to be run from the service to the CT cabinet for safety. This will likely satisfy the NEC and provide for some level of safety but this also adds 250 feet or so of conductor impedance to a fault that occurs at the CT cabinet. The fault will have to travel back to the service and then back to and through the CT cabinet to reach the utility transformers where we hope it will be cleared by a fuse...
If you are a contractor or code official in southern NJ, be aware...
 
OK...here's a POCO perspective. CT cans are on the line side of the main service disconnect, and the neutral is not required to be bonded ahead of the service disconnect enclosure. The metal conduit and enclosure must be still bonded, though. We do not allow a bond of the neutral in a CT can or bussed gutter because the neutral bond (MBJ) is considered a customer connection. That includes the GEC. Our rules state that no customer connection is allowed within a sealable compartment. The only exception is when a line side MSD is installed ahead of more than six service disconnects, as required by code. We only ground and bond the neutral at the transformers. It is bonded again at the service disconnect by the customer. When we test a service prior to energization, we lift the neutral at the transformer and the service panel and check for any grounds on the neutral and the phases. Undergroud pulls through metallic conduit and overhead tri-plex can sometimes be damaged during installation. Isolated neutral standoffs have also been known to be grounded. We want to know our end is ready for power.
 
meternerd said:
OK...here's a POCO perspective. CT cans are on the line side of the main service disconnect, and the neutral is not required to be bonded ahead of the service disconnect enclosure. The metal conduit and enclosure must be still bonded, though. We do not allow a bond of the neutral in a CT can or bussed gutter because the neutral bond (MBJ) is considered a customer connection. That includes the GEC. Our rules state that no customer connection is allowed within a sealable compartment. The only exception is when a line side MSD is installed ahead of more than six service disconnects, as required by code. We only ground and bond the neutral at the transformers. It is bonded again at the service disconnect by the customer. When we test a service prior to energization, we lift the neutral at the transformer and the service panel and check for any grounds on the neutral and the phases. Undergroud pulls through metallic conduit and overhead tri-plex can sometimes be damaged during installation. Isolated neutral standoffs have also been known to be grounded. We want to know our end is ready for power.
Click to expand...
Yet a typical self contained metering socket has the grounded conductor lug(s) bonded to the cabinet.

POCO's around here bond the grounded conductor to every enclosure if it isn't done so already within contained equipment.
 
meternerd said:
OK...here's a POCO perspective. CT cans are on the line side of the main service disconnect, and the neutral is not required to be bonded ahead of the service disconnect enclosure. The metal conduit and enclosure must be still bonded, though. We do not allow a bond of the neutral in a CT can or bussed gutter because the neutral bond (MBJ) is considered a customer connection. That includes the GEC. Our rules state that no customer connection is allowed within a sealable compartment. The only exception is when a line side MSD is installed ahead of more than six service disconnects, as required by code. We only ground and bond the neutral at the transformers. It is bonded again at the service disconnect by the customer. When we test a service prior to energization, we lift the neutral at the transformer and the service panel and check for any grounds on the neutral and the phases. Undergroud pulls through metallic conduit and overhead tri-plex can sometimes be damaged during installation. Isolated neutral standoffs have also been known to be grounded. We want to know our end is ready for power.
Click to expand...
I don't think the op is talking about putting the MBJ on the ct can. It would be called a "supply side bonding jumper", which the customer should not need access to. We have the same deal here that we cannot put a MBJ in a meter, but the neutral is still bonded to the can.
 
kwired said:
Yet a typical self contained metering socket has the grounded conductor lug(s) bonded to the cabinet.

POCO's around here bond the grounded conductor to every enclosure if it isn't done so already within contained equipment.
Click to expand...

The only time the neutral is grounded in the meter enclosure is when it's a combo with the main disconnect in the panel (which is now standard because of requirements for outside service disconnects), but those western utilities that go by EUSERC (Electric Utility Service Equipment Requirements Committee) require that the utility section is separated by a barrier and is sealable. The grounding of the neutral is done in the unsealed disconnect side. The utility service neutral lands on an insulated neutral terminal which is bussed or wired to the customer side before it's grounded. Older services may differ, but that's the way it's done now.
 
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meternerd said:
OK...here's a POCO perspective. CT cans are on the line side of the main service disconnect, and the neutral is not required to be bonded ahead of the service disconnect enclosure.
Click to expand...

Agreed.

The metal conduit and enclosure must be still bonded, though.
Click to expand...

Agreed

We do not allow a bond of the neutral in a CT can or bussed gutter because the neutral bond (MBJ) is considered a customer connection. That includes the GEC. O
Click to expand...

It would not be the MBJ, that would still be at the service disconnect.

This bond would simply be an bonding jumper.

Bonding Conductor or Jumper. A reliable conductor to
ensure the required electrical conductivity between metal
parts required to be electrically connected.
Click to expand...


ur rules state that no customer connection is allowed within a sealable compartment.
Click to expand...

And the safety reason for this is?




When we test a service prior to energization, we lift the neutral at the transformer and the service panel and check for any grounds on the neutral and the phases. Underground pulls through metallic conduit and overhead tri-plex can sometimes be damaged during installation. Isolated neutral standoffs have also been known to be grounded. We want to know our end is ready for power.
Click to expand...

And that is the answer, to make life easier for the linemen a customer like the OPs has to pay for a lot more wire and add lot of impedance to the fault path.

Here we purchase CT cans specified by the power companies, below is a pretty typical example I found on the net. As you can see the neutral comes factory bonded to the case.

I was very surprised to learn not all power companies use ones like this.
 

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SparkyHC said:
In New Jersey we have three Pocos. Since the day I started we have been landing the supply side grounded conductors or neutrals in the CT cabinets of all the Pocos. This directive "not" to allow termination of the neutrals in the CT cabinet is new as far as I am aware. Why, is only speculation at this point. To comply with their directive at this particular project, the neutrals will pass through the CT cabinet unbroken, travel another 125 feet to the service gear where they are bonded to ground with the GEC. What bothers me is that they are asking for grounding conductors to be run from the service to the CT cabinet for safety. This will likely satisfy the NEC and provide for some level of safety but this also adds 250 feet or so of conductor impedance to a fault that occurs at the CT cabinet. The fault will have to travel back to the service and then back to and through the CT cabinet to reach the utility transformers where we hope it will be cleared by a fuse...
If you are a contractor or code official in southern NJ, be aware...
Click to expand...

Terminating the neutral in the CT can is fine, but it seems to me that grounding the neutral ahead of the service disconnect sets up a parallel path for neutral current. Same reasoning as why we don't bond sub-panel neutrals. What if the neutral becomes disconnected between the CT can and the service disconnect enclosure? How? I have seen newly installed commercial switchgear that contain a "swing-link" neutral disconnect link where the link was loose or never connected. Missed by the building inspector. These are downstream of the CT section and ahead of the MBJ. Utilities normally don't look beyond the metering sections, because it's not their jurisdiction.

Wired your way, if not corrected, normal neutral current would have to flow from the CT ground to the MBJ and then to the service neutral and nobody would realize that's what was happening until smoke showed up. Objectionable current? Someone smarter than me must have decided to do it this way because that's pretty much the way I've always seen it done. But then, I've only done metering in California and Alaska.
 
iwire said:
Here we purchase CT cans specified by the power companies, below is a pretty typical example I found on the net. As you can see the neutral comes factory bonded to the case.

I was very surprised to learn not all power companies use ones like this.
Click to expand...

The CT can you showed would not be acceptable here for those utilities that use EUSERC as their construction standard for services for the reason I stated before. I also don't use voltage transformers on 480. Meters are rated 600V. Unfused directly to the test switch and meter. If working it hot, we wear the suit. Unfused PT failure can be ugly. Fused is also a problem. Reason being, blow a fuse and lose a phase of metering until it's noticed. Even most solid state meters are powered from A phase, so blowing B or C can go unnoticed for a while. Especially since with remote read meters, meter readers seldom actually visit the meter. Funny that customers never call when their bill suddenly goes down. There are alarms that can work around it, but that too causes problems. Such a tough job....:weeping:

ur rules state that no customer connection is allowed within a sealable compartment. And the safety reason for this is?

No safety reason....but we dont want the customer cutting our seals to access the GEC or any other customer connections.
 
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