C.T. cabinet

[slalom skier]

I have a ct cabinet with 3 - 3 inch emt pipes going to the service disconnect bonding locknuts both sides bonding jumper in disconnect I am being told I have to bond all three neutrals to the ct cabinet is this correct

 

[infinity]

The bonding locknuts are for bonding the service raceway so they're only required on one side but both sides works too. The CT cabinet is bonded to the system neutral if you had three then IMO they all should get bonded to the enclosure.

 

[electrofelon]

The bonding locknuts are for bonding the service raceway so they're only required on one side but both sides works too. The CT cabinet is bonded to the system neutral if you had three then IMO they all should get bonded to the enclosure.

I agree, but I believe if he had bonding locknuts on both sides, then the neutrals could pass through the CT cabinet without landing on it do you agree? That said, every modern CT cabinet I have seen has a neutral terminal bar and the POCO might want it that way for easy neutral access for metering purposes.

 

[texie]

I have a ct cabinet with 3 - 3 inch emt pipes going to the service disconnect bonding locknuts both sides bonding jumper in disconnect I am being told I have to bond all three neutrals to the ct cabinet is this correct

No, it is not correct based on what you describe. If you have properly installed and sized bonding per 250.92 on each end of those metallic conduits then the CT cabinet is bonded to the neutral conductor thru the main bonding jumper in the service disconnect. Now if you had only put 250.92 bonding on 1 end that would change things.
I should add that CT cans can be purchased with bonded neutral bars in which case you could only bond 1 end and be compliant. If you have a CT can that does dot have provisions for a bonded neutral the way you describe is compliant. The bottom line is that all metallic items on the line side of the of the service disconnect have to comply with 250.92 and there are various ways to do this.

 

[meternerd]

The bonding locknuts are for bonding the service raceway so they're only required on one side but both sides works too. The CT cabinet is bonded to the system neutral if you had three then IMO they all should get bonded to the enclosure.

Just a POCO comment...not all CT cabinets are bonded to the system neutral (at least not at the CT enclosure), only to ground. There is no requirement that I'm aware of that requires a CT enclosure to be bonded to neutral, only to ground. Many of our installations had remote CT cabinets separate from the service disconnect and the neutral passed through but did not terminate in or allow access to the neutral. Neutral and ground bonding is required only at the service disconnect.

 

[infinity]

Just a POCO comment...not all CT cabinets are bonded to the system neutral (at least not at the CT enclosure), only to ground. There is no requirement that I'm aware of that requires a CT enclosure to be bonded to neutral, only to ground. Many of our installations had remote CT cabinets separate from the service disconnect and the neutral passed through but did not terminate in or allow access to the neutral. Neutral and ground bonding is required only at the service disconnect.

What is the "ground" connected to besides the CT cabinet?

 

[meternerd]

There's no separate ground. I should have said the bonding of the cabinet, conduit, etc. CT cabinet and associated conduits are bonded just like any other service side raceway. I know that some local AHJ's require a neutral bond, though. Alaska is one. Not sure why. The "ground" is where we connect the non-polarity "CT return" connections. We require all CT returns to be grounded at the CT. It can be to the enclosure or a ground bus. Safety rather than a metering consideration, since meter current elements do not reference ground or neutral.

 

[texie]

Just a POCO comment...not all CT cabinets are bonded to the system neutral (at least not at the CT enclosure), only to ground. There is no requirement that I'm aware of that requires a CT enclosure to be bonded to neutral, only to ground. Many of our installations had remote CT cabinets separate from the service disconnect and the neutral passed through but did not terminate in or allow access to the neutral. Neutral and ground bonding is required only at the service disconnect.

If the neutral was not bonded the enclosure at this remote CT enclosure, do you then do you have a supply side bonding jumper from the main disconnect to the CT enclosure? If you don't bond the neutral to the CT enclosure then the only option to be compliant would be to use a supply side bonding jumper.

 

[electrofelon]

Just a POCO comment...not all CT cabinets are bonded to the system neutral (at least not at the CT enclosure), only to ground. There is no requirement that I'm aware of that requires a CT enclosure to be bonded to neutral, only to ground. Many of our installations had remote CT cabinets separate from the service disconnect and the neutral passed through but did not terminate in or allow access to the neutral. Neutral and ground bonding is required only at the service disconnect.

I am confused. I don't think you are talking about unrounded systems here.... Or by " not bonded to neutral" do you mean just not "directly" connected to neutral but tied to neutral downstream/upstream with a bonding jumper?

 

[kwired]

"250.80 Service Raceways and Enclosures.
Metal enclosures and raceways for service conductors and equipment shall be connected to the grounded system conductor if the electrical system is grounded or to the grounding electrode conductor for electrical systems that are not grounded."

CT cabinets would typically enclose service conductors.

If the CT cabinet is on the supply side of the "service point", NEC doesn't apply to it, chances are the utility is installing it as well and will follow whatever rules they have.

 

[meternerd]

In those cases where there is no neutral splice or connection inside the CT enclosure (insulated neutral passes through the CT can without termination or splice), as is fairly common for remote CT enclosures, we would not require a splice, tap or termination of the grounded conductor within the CT can. I suppose technically it is bonded to the grounded conductor by way of the bonding conductor at the service disconnect, but we don't require service side main bonding jumpers. No different than when service conductors pass through pull boxes in a conduit run before entering the service disconnect enclosure. Bonding of metallic conduit and bonding bushings, but no bonding jumper to the grounded conductor. But like I said, I think it's an AHJ call whether to require it or not.