At a recent training session, there was discussion about what rules apply to conductors installed on the line side of the service disconnecting means. One comment indicated that these conductors were service conductors, so the requirements for services and service conductors apply. It was interesting, and one that led to my realization that there is an apparent need to address a gap in the NEC.

This edition of Code Comments gets into the details of this issue. It is intended to identify some existing rules that could apply to these installations, and to put forward suggestions for NEC revisions that could assist users with proper Code application.

First, it’s a good approach to use the NEC definitions to clarify requirements that use defined words and terms. Article 100 is extremely important here. A review of the terms “service” and “service conductors” do not appear to align with all conductors connected to the line side of the service disconnecting means. Service conductors typically terminate at the service disconnecting means, another term defined in Article 100.

Section 230.82 addresses equipment connected to the supply side of the service disconnect. The connection of the 12 items listed in this section is often either by direct connection or through conductors. You should not refer to all of these conductors as service conductors because of the definition of that term. From a practical standpoint, these are supply-side conductors connected ahead of the service disconnection means and allowed for each of the purposes described in 230.82(1) through (12).

If these conductors are considered service conductors, then many other requirements for actual service conductors are triggered. A few examples are the line-side conductors to connect Type 1 surge protective devices, the line-side conductors that connect energy management systems and others. These are not service conductors, but they are connected to the supply side of the service disconnect, which does trigger some requirements that are generally a bit more robust than if there were overcurrent protection ahead of these conductors. As an example, the grounding and bonding conductors installed with these supply-side conductors would need to meet more restricted rules found in Section 250.92 and 250.102(C).

Another issue worth mentioning is the requirements for disconnects at the termination of the supply-side conductors. This is typically where the first overcurrent protective device for such conductors is inserted. Is this considered a service disconnect? Does it always have to be rated as such? Does it have to meet the requirements for service disconnects found in Part VI of Article 230? It does not seem that all these requirements can be met for the equipment listed in Section 230.82(1) through (12).

Yet another concern to add fuel to this discussion is that Section 230.7 indicates that circuit conductors other than service conductors shall not be installed in the same raceway, cable, handhole enclosure or underground box as service conductors. That said, if supply-side conductors are referred to as service conductors, then many other rules would apply to their usage, in many impractical ways.

It is important to realize that conductors connected to the supply (line) side of the service disconnecting means should call for strengthened wiring methods and robust grounding and bonding methods. After all, there is little to no protection on the upstream side of these supply-side conductors.

The NEC does define and address tap conductors, but those are clearly not service conductors or supply-side conductors. Even so, opportunities exist to clarify what requirements in the Code (specifically Article 230) can be applied to supply-side conductors that are not service conductors.

The other related issues are the ratings of equipment connected to the supply-side conductors. While some of the items in 230.82 call for a service rated disconnect, others do not. Another open-ended issue seems to be length limitations on supply-­side conductors addressed in 230.82.

A conductor length limitation here would be relevant or should at least be a consideration for NEC improvement. While often addressed as part of listing requirements and installation instructions for Type 1 SPDs, it seems that the supply-side conductor length for other equipment covered by 230.82 is not currently addressed. This edition of Code Comments is intended to raise awareness and possible involvement in Code development to fill some of these gaps. This could result in clearer and more accurate application of rules to supply-side conductors.