Contact the Utility Upfront:
When making connections or modifications to switchgear on the line side of the service disconnect, we recommend contacting the utility to notify them of your intentions. This should be done before any modifications are made as most utilities have interconnection applications or requirements. Contacting the utility in the initial stages of construction is critical to avoid surprises down the road. If the project is for solar interconnection the same solar installation package submitted to the local building department can be used for utility review. If it is another type of modification, a submittal of photos along with a single line diagram should get the ball rolling. The photos should include a minimum of the: overall electrical room, sections of switchgear, nameplate rating tag(s), and specific area marked up to show how modifications would look. Once documentation has been approved, a shut-down can be scheduled with the utility such that work can be conducted while the gear is de-energized.
Single Meter Applications:
For single meter applications a tap/interconnection must generally be placed between the meter and the main disconnect. In these instances, it is critical that the tap be placed in the main disconnect section, not in the utility sections. Unless permission has been obtained from the utility, connections cannot be made in the CT or Meter compartments. In addition, field installed conductors cannot pass through these compartments. There is generally a barrier that separates the main disconnect from the CT section. This should be considered the “Do Not Cross Plane”. If there is no existing barrier here, the utility may require that one be installed.
In multi-meter applications the tap/interconnection could be placed in the Utility Pull Section, or in the main disconnect section. Each have their advantages and disadvantages. There is generally more room for making connections in the pull section, but much like the CT section, the pull section is under the utility’s jurisdiction. Unlike the CT section, taps are more often allowed to be in this section but may be subject to additional requirements. If allowed, the utility may want to see a bus extension to separate the utility connections from tap connections. In addition, they may want to see a barrier placed between these connection points, and sometimes may even require the cover to be modified such that the new tap section would have its own separate cover. Tapping in the main disconnect section on the other hand is not subject to as many requirements, but the space from a pull section barrier to the main disconnect line terminals may be very limited, making a tap difficult to perform. In this scenario, small bus extensions (bus flags) can come in handy to shift the tap position from the existing bus surface to an adjacent area with more room, wire bending space, or accessibility.
Many line-side taps are conducted after hours or during weekends due to the power shut down requirement. During these hours, building inspectors are typically not working. The utility, however, may still require the inspector’s sign-off before they will restore power. For after-hours shut-downs, the inspector should be contacted in advance to sign a release allowing the utility to re-energize without their presence on-site. Otherwise, the utility may refuse to shut power off or turn it back on, which can be problematic.
To see our Part I blog regarding UL equipment requirements for switchgear click on Part I (UL 891 Requirements). For our Part II blog on NEC requirements click on Part II (NEC Requirements). For more information on how we can assist with Field Evaluations click on Field Evaluation Service
For a quotation for Field Evaluation Services click Quotation