Service Conductors

The term “Service Conductors” is used many times in the code placing specific requirements on these conductors. It’s critical that you understand what a service conductor is to determine what portions of the code apply.

It’s not clear when the term service conductors went into the Code but the 1940 edition of the document had this term and the 1923 edition did not. The following are the critical historical moments in time that impacted the language of the code.

1940 NEC – 1953 NEC

As noted above, this term is in the 1940 edition of the code but not the 1923 edition of the code. Code documents were not available to indicate exactly when this term went in to the document. What you will see is that the definition uses key components in the system that enable the utility to get power to a structure. It even uses the reference of the street. In this definition you’ll see the reference to overhead conductors which later gets broken out on its own. You’ll see that in the defined term overhead service conductors.

Here is what we find in the 1940 edition of the code for the definition of the term “Service Conductors”:

Service Conductors: That portion of the supply conductors which extends from the street main or duct or from transformers to the service equipment of the premises supplied. For overhead conductors this includes the conductors from the last line pole to the service equipment.

1956 NEC – 1999 NEC

During the 1956 cycle, changes were made to the definition of service conductors. My references indicate that this terms’ definition was simplified and it appears that the reference to overhead conductors was removed. This is when the defined term Overhead Service Conductors entered the document.

Service Conductors: The supply conductor which extend from the street main, or from transformers to the service equipment of the premises supplied.

1999 NEC – Present

The 1999 edition of the code replaces the text “from the street main, or from transformers” with “from the service point”. it also replaces the text “to the service equipment of the premises supplied” with “to the service disconnecting means”. What has yet to be defined is what a service disconnecting means is.