Click on the following link to view RISBC-5 Rhode Island Electrical Code Title 5 as shown below: https://rules.sos.ri.gov/regulations/part/510-00-00-5

Delete 230.24(A) Exception No. 5

Substantiation for deletion of 230.24(A) Exception No. 5

This exception to the 2020 National Electrical Code (NEC) will permit overhead service conductors with a vertical clearance of not less than three feet (3’) to pass over the surface of a flat roof, if the roof area is guarded or isolated. The justification for this exception was to correlate the NEC^® with allowances in the National Electrical Safety Code (NESC). Currently, the NESC allows conductors to be a minimum of nine hundred millimeters (900 mm) (three feet (3’)) above the roof, if the area is guarded or isolated. However, this justification is flawed, because the NEC^® applies to installations on the load side of the service point and the NESC applies to installations on the supply side of the service point.

Section 230.24(A) applies to Overhead Service Conductors, which are defined in the NEC^® as the overhead conductors between the service point and the first point of connection to the service-entrance conductors at the building or other structure. Service-Entrance Conductors of an overhead system are defined in the NEC^® as the service conductors between the terminals of the service equipment and a point usually outside the building, clear of building walls, where joined by tap or splice to the service drop or overhead service conductors. Clearly, under these definitions, overhead service conductors are within the scope of the NEC^® and not the NESC.

It is the opinion of this committee that when conductors pass over roof surfaces other than those addressed in Exceptions 2, 3, and 4, the minimum vertical clearance of not less than two and one half meters (2.5 m) (eight feet (8’)) should be maintained, because guarding and isolation in locations that are not under the exclusive control of the utility will not provide equivalent safety as currently allowed in Exceptions 2, 3 and 4. As an example: The flat roof of a strip mall that is enclosed by a fence, with a locked gate is considered “isolated.” Equipment such as HVAC and CATV is mounted on the roof and those servicing this equipment have access (a key) to the roof and may come in contact with the conductors.

If the NEC^® Technical Committee CMP-4 feels the need to correlate these documents, modifications should have been made to the less restrictive NESC and not the NEC^®.

Conductors installed and maintained by the electric utility on the supply side of the service point are beyond the scope of the NEC^®. The NESC applies to utility work and its requirements are different from those of the NEC^® because these installations are fundamentally different than those for premises wiring. And the three elements that make that so are is that the utility has exclusive control, restricted access and qualified persons maintain the installation.