A remote CT metering cabinet does not automatically need the same grounding arrangement as a cabinet supplied by a feeder. First establish whether its primary conductors are ahead of the service disconnect. On a grounded service, the grounded service conductor can provide the enclosure bonding path where the adopted rules permit. A separate equipment grounding conductor is not automatically required simply because the cabinet stands outside. However, metallic raceways and enclosure connections still need an approved, correctly sized service bonding arrangement.
Locate the service disconnect
Start with the electrical one-line diagram, not the distance between the metering cabinet and the building. Trace the primary power conductors from the source, through the CT cabinet, to the service disconnecting means.
If the cabinet contains service conductors ahead of that disconnect, evaluate its bonding as supply-side service bonding. If a service disconnect feeds the cabinet, evaluate the cabinet under the applicable load-side rules instead. Metering equipment can appear in either location.
An outdoor switch, meter seal, or enclosure marked for emergency operation does not settle the classification by itself. Confirm the equipment markings and approved service arrangement. Likewise, the utility service point establishes an ownership or responsibility boundary; it does not necessarily identify the service disconnect.
Mark these items on the drawing:
- Utility service point and ownership boundary.
- CT cabinet primary conductor route.
- Service disconnect location and equipment identification.
- Grounded service conductor route and designated bonding connections.
- Every metallic raceway segment between the service equipment components.
This article assumes a grounded service with a grounded conductor available for the approved bonding arrangement. Do not transfer that assumption to an ungrounded service or another system configuration without reviewing its specific requirements.
Separate the three grounding functions
The grounded service conductor, equipment grounding conductor, and grounding electrode conductor serve different purposes. Calling all three a ground wire hides the distinction that determines the cabinet connections.
| Conductor or connection | Main function | Meaning for the CT cabinet |
|---|---|---|
| Grounded service conductor | Carries normal return current where applicable and participates in the approved service fault-return path | May bond supply-side metal parts where the adopted rules permit |
| Equipment grounding conductor | Connects load-side equipment metal to the source fault-return path | Normally accompanies feeder or branch-circuit conductors, not as a substitute for required service bonding |
| Supply-side bonding jumper | Maintains electrical continuity between service metal parts | May be needed for raceways, fittings, or enclosure connections regardless of whether a separate equipment grounding conductor is present |
| Grounding electrode conductor | Connects the designated system connection to the grounding electrode system | Does not replace the metallic fault-return path to the source |
For a grounded service cabinet ahead of the service disconnect, bonding through the grounded service conductor is an established arrangement. Whether an additional conductor is required depends on the complete service bonding design, raceways, fittings, and adopted requirements.
Therefore, the answer is not simply to omit an extra wire. The cabinet still needs a documented connection that provides the required fault-return path. An additional wire may function as a supply-side bonding jumper rather than a load-side equipment grounding conductor.
On the load side, normally keep the grounded conductor isolated from the enclosure and bond the enclosure through the equipment grounding path. Limited metering exceptions require specific review; they are not permission to add neutral-to-case connections throughout an installation.
Use the grounding and bonding guide for the underlying fault-path principles. Earth is not an effective ground-fault current path, and a nearby ground rod does not resolve a missing cabinet bond.
What ratings and checks do not establish
An environmental enclosure rating does not approve a cabinet for service metering. It does not establish utility acceptance, conductor bending space, bonding hardware suitability, or the acceptability of the completed electrical assembly.
Our stainless wall-mount enclosures are rated NEMA 4X / IP66 by the manufacturer; not UL listed. Those manufacturer ratings describe environmental protection, not approval for a particular CT installation.
The wall-mount enclosure category provides enclosure candidates, not a utility-approved metering cabinet list. Confirm acceptance before selecting a catalog box for this duty.
A continuity reading also has limits. A low-current meter can indicate a connection without proving its ability to carry available fault current. It cannot establish correct jumper sizing, fitting suitability, or mechanical integrity by itself.
An unintended parallel path may also produce a reassuring reading across an otherwise defective connection. Verification must combine the approved drawings, component instructions, physical inspection, and an appropriate commissioning procedure.
Keep all inspection and testing within an established electrical safety procedure. Opening the service disconnect can leave the CT cabinet and incoming service conductors energized. Never open a CT secondary circuit while primary current flows; follow the metering equipment's documented isolation and shorting procedure.
Bond every metallic service raceway
A bonded cabinet does not automatically mean every connected raceway is correctly bonded. Follow each metallic path through hubs, connectors, couplings, locknuts, and enclosure walls.
Service raceway bonding requires particular attention because a fault may occur ahead of the service disconnect's overcurrent protection. Do not assume ordinary locknuts or incidental contact provide the required bonding connection. Specify fittings and bonding methods suitable for the actual service application.
Check the enclosure entry construction as well. Concentric or eccentric knockouts, reducing washers, coatings, and loose fittings can affect the permitted bonding method. A dedicated bonding connection may be necessary even when the conduit appears mechanically secure.
With a nonmetallic raceway, there is no metal conduit path between cabinets. The approved design must still provide the required bonding of the metal CT cabinet and any isolated metallic fittings.
Supply-side bonding jumper sizing follows service bonding requirements. Do not automatically apply a load-side equipment grounding conductor size selected from a breaker rating. Parallel service conductors and multiple raceways need their own sizing and routing review.
The article on cable gland bonding requirements explains why a sealed entry is not necessarily an electrical bond. For service metering, the fitting must additionally suit the approved service bonding arrangement.
Confirm the utility and inspection requirements
Obtain the utility's current metering requirements before finalizing the cabinet layout. They may control the cabinet construction, CT supports, conductor arrangement, terminal provisions, access, and sealing requirements.
Utility requirements and electrical inspection requirements address different responsibilities. Acceptance by one does not automatically establish acceptance by the other. Resolve both before fabrication.
Send the authority having jurisdiction a marked one-line diagram and the proposed bonding detail. Ask for confirmation of these points:
- Whether the CT cabinet is being treated as supply-side service equipment or load-side metering equipment.
- Where grounded-conductor-to-enclosure connections are permitted or required.
- How each metallic service raceway will be bonded.
- Which conductor sizing rules apply to the proposed bonding jumpers.
- Where the grounding electrode system connects and whether an additional connection is required at this location.
- Whether enclosure listing, assembly evaluation, or other approval documentation is required.
Do not add or remove a grounded-conductor bond merely to eliminate current measured on a metallic raceway. Service arrangements can include parallel metallic paths. Unexpected current requires a review of the complete installation, not an isolated cabinet modification.
Also confirm access and mounting requirements. Outdoor mounting must preserve both the cabinet seal and the bonding arrangement. The article on mounting screws through an outdoor enclosure without leaks addresses mounting penetrations; mounting hardware should not become an assumed electrical bonding connection.
What to specify for the cabinet
Order the enclosure only after the bonding scheme and utility arrangement are settled. We build custom enclosures with the specified material, width, height, depth, and cutouts, from one piece. Suitability for service metering still depends on the approved design and required acceptance.
Include the following information with the enclosure specification:
| Specification item | Information to provide |
|---|---|
| Electrical position | Supply side or load side of the identified service disconnect |
| Service configuration | Voltage, phase arrangement, grounded conductor, and conductor quantities |
| Acceptance requirements | Utility cabinet requirements and required inspection or evaluation documentation |
| Bonding arrangement | Connection diagram identifying the grounded conductor, cabinet bond, and raceway bonding jumpers |
| Bonding hardware | Required connection locations, conductor material and size range, and compatible terminal hardware |
| Raceway entries | Quantity, size, entry position, fitting type, and bonding provisions |
| Internal layout | CT assembly dimensions, supports, conductor routing, and required bending and termination space |
| Environment | Water exposure, corrosion conditions, temperature range, and required enclosure rating |
| Access | Door clearance, metering access, sealing requirements, and maintenance space |
Require the drawing to identify bonding provisions explicitly. A generic grounding stud note does not establish the terminal capacity or the connection method needed for service bonding.
The final decision is straightforward: classify the cabinet electrically, document the fault-return path, and obtain acceptance before ordering. Physical separation from the service disconnect does not, by itself, create a requirement for a separate equipment grounding conductor.
Enclosures for this job
Catalog sizes that suit the job this article answers, picked from its subject; open one for its full specifications.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 60 × 36 × 16 in | 304 stainless | 60 x 36 x 16 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 48 × 36 × 16 in | 304 stainless | 48 x 36 x 16 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 60 × 36 × 12 in | 304 stainless | 60 x 36 x 12 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
Does a remote CT cabinet always need a separate equipment grounding conductor?
Not automatically. On a grounded service ahead of the service disconnect, the grounded service conductor may provide the enclosure bonding path where the adopted rules permit. Separate supply-side bonding jumpers may still be required for raceways or connections. Confirm the complete arrangement with the utility and authority having jurisdiction.
Can the neutral bond a CT cabinet downstream of the service disconnect?
Do not assume so. Load-side enclosures normally use an equipment grounding path while the grounded conductor remains isolated from the case. Specific metering exceptions may apply under the adopted rules, but they require review of the actual installation. A supply-side bonding detail is not automatically suitable downstream.
Does a ground rod replace the bonding connection at a CT cabinet?
No. A grounding electrode connection does not replace the required fault-return path to the source. The cabinet, metallic raceways, and other applicable metal parts still need the bonding arrangement required for their electrical position. Establish any electrode requirement separately with the utility and authority having jurisdiction.
Is an outdoor enclosure rating enough to qualify a cabinet for CT metering?
No. Environmental protection does not establish utility acceptance, electrical assembly approval, conductor clearances, or bonding suitability. Confirm the utility's cabinet requirements and the inspection requirements before ordering. The enclosure specification should identify the approved layout, raceway entries, bonding hardware, and any required evaluation documentation.
