Where the utility ends and your responsibility starts
Article 230 is organized by the physical path of the service, front to back. Read it that way and it stops being a list.
On this page
The article follows the wire
Article 230 is laid out in the order the power arrives: overhead or underground conductors, then the service entrance conductors, then the equipment, then the disconnecting means, then overcurrent protection.
That ordering is the fastest way to find anything in it. Ask where on the path your question sits, and go to that part.
Most people try to memorize it as a list of rules and lose time hunting. It is a sequence.
Clearances are about what is underneath
Overhead conductor clearances vary by what is below them and by the voltage. A conductor over a roof is treated differently from one over a driveway, which is treated differently from one over a pool.
So the question to ask is not how high, it is above what. Find the surface the question describes, then read the clearance for it.
Underground has its own burial depth rules, which similarly vary by what is above and by the wiring method.
The disconnect rule that generates most questions
There is a limit on how many service disconnecting means are permitted (NEC 230.71), and a separate section requires the permitted two to six to be grouped and individually marked (NEC 230.72). Two sections, and a question about grouping is answered by the second one.
Read that section directly. The number, and what counts as one disconnect for the purpose of counting, is the whole question and it has changed across recent editions.
What has not changed is the underlying idea: someone arriving at a building in an emergency has to be able to kill all of it without hunting.
Service conductors are unusual in one specific way
Service entrance conductors are on the supply side of the service disconnect, which means there is no overcurrent device upstream of them.
That is why bonding rules for service raceways are stricter than for ordinary feeders, and why the grounded conductor has to be brought to the service equipment even when no load needs it.
If you understand that one fact, a large part of Article 230 and a large part of Article 250 stop looking arbitrary.
What the exam asks here
- A clearance, given a surface and a voltage.
- How many disconnects are permitted, and what counts as one.
- Whether something may be tapped ahead of the service disconnect.
- Where the grounded conductor has to land, and the reason behind it (NEC 250.24(D)).
Tab 230.71 and 230.72 together. Between them they come up more than the rest of the article combined, and they are easy to confuse because they sit side by side.
What this page cites
- NEC 230.71 Maximum number of service disconnects and what counts as one.
- NEC 230.9 Clearances from building openings.
- NEC 250.24 The service grounding connection this article depends on.