National Electrical Code Articles and Information
National Electrical Code Top Ten Tips: Article 230 -- Services
by Mark Lamendola
Based on the 2023 NEC.
Please note, we do quote from copyrighted material. While the NFPA
does allow such quotes, it does so only for the purposes of education
regarding the National Electrical Code. This article is not a substitute
for the NEC.
These are the 10 NEC Article 230 items we deem most important, based
on the pervasiveness of confusion and the potential costs of same.
- Figure 230.1 graphically shows which parts of NEC Chapter 2
apply to the various parts of the power distribution system that touch on services. This
figure should be your "road map" to applying the
requirements of NEC Chapter 2, if you are starting with a "green project" (aka, a clean slate, aka ground up, aka new construction). Why is it a reference to Chapter 2, and not just Article 230? Because it contains references to Articles 210, 215, and 250 in addition to Article 230. Article 250 applies to branch circuits , feeders , and services . Services interact with all of these, so this figure belongs in Atticle 230.
- 230.2 addresses the issue of the number of services. It
balances the need for being able to shut off the power (for fire
fighting purposes) at a central point with the practical aspects of
running 2000A or more through a single service, plus it addresses
other concerns. One item that (much) older Codes did not require is a
plaque showing the location of each service in a multi-service
facility—and that such a plaque be posted at each service. It is
wise to "retro-comply" with this Code requirement.
- "Vegetation such as trees shall not be used for
support of overhead service conductors." [230.10. ]In fact, you don't want vegetation even close to these conductors.
- 230.24 (very briefly) discusses clearances. "Overhead service conductors
shall not be readily accessible…." (A) details the clearance
above roofs, plus the exceptions. (B) details the clearance from
ground, plus the exceptions. (C), (D), and (E) refer to other Sections (including Sections in other Articles).
- 230.33 allows splicing or tapping of service-lateral
conductors, if done per the several Code Sections referenced.
- Every service drop or lateral shall supply only
one set of service-entrance conductors [230.40]. If you have more than one service entrance, you need more than one service drop or lateral.
- Size service entrance conductors for at least the
"sum of the noncontinuous loads plus 125 percent of continuous
- 230.43 limits the wiring methods to 21 specific types. The 20th type, Type TC-ER Cable, was added to the list with the 2020 revision. The 21st type, Flexibe bus systems, was added with the 2023 revision.
- 230.82 limits the equipment you can connect to the supply side
of the service disconnect to 12 specific items. The 10th and 11th were added with the 2020 revision. The 12th was added with the 2023 revision.
- Part VII begins with 230.90 and covers overcurrent protection for service equipment.
This contains important concepts that often don’t get implemented
correctly. For example, "no overcurrent device shall be
inserted into a grounded service conductor except a circuit breaker
that simultaneously opens all conductors of the circuit" [230.90(B)]. Performance testing of the ground fault system is another conveniently overlooked requirement [230.95(C)].