National Electrical Code Articles and Information
National Electrical Code Top Ten Tips: Article 225 -- Outside Branch Circuits and Feeders
Based on the 2017 NEC
by Mark Lamendola
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 225 items we deem most important, based
on the pervasiveness of confusion and the potential costs of same.
- 225.1. Read the scope carefully. In many instances of
disagreement with the electrical inspector, folks are misapplying
- Table 225.3 clearly shows were other NEC Articles apply to
specific equipment and conductors.
- 225.4. Overhead conductors outdoors must be insulated or covered (per
Article 100, a covering is not insulation) when within 10 feet of a
building—except as stated.
- 225.7 gives various rules for outdoor lighting. Note, there
are clearances established for circuits exceeding 120V.
- 225.14 provides the rules for open conductor spacing. For
example, "Open conductors shall be separated from open
conductors of other circuits or systems by not less than 100 mm (4
- 225.18 is "Clearance for Overhead Conductors and Cables." This has often
been a source of contention in court. It’s best to exceed the
requirement by a foot or two, as design and installation are two
different things and being off by an inch can burn you, despite the
fact that it’s substantial compliance and obviously satisfies the
intent of the Code. For one thing, a crane operator won’t know you
are an inch low, and that can get somebody killed. These are minimal
heights. Pay attention to the type of area a cable will pass over,
and use the highest clearance if in doubt. Also, create a clear path
for fire ladder equipment and other emergency apparatus.
- 225.19 gives the clearances from buildings (1000V or less) —the comments we
gave for 225.18 also apply here.
- 225.34 addresses the grouping of disconnects. You can have a
single disconnect on a service. But, if you have more than one, you
must group all of them (except a fire pump disconnect, which has
special requirements). You can have a maximum of 6 disconnects per
- 225.37 covers an issue most installers routinely ignore or
inadequately comply with. You must have a circuit directory or
plaque (with some exceptions noted) to identify the circuits. The
intent here is not to have vague text, but to clearly identify the
circuits. This isn’t just for the convenience of the owner. It’s
also for the use of the first responders (e.g., for stopping an
electrocution), fire department workers and other emergency workers.
It is illegal to shirk responsibility here, and this particular
violation can carry heavy personal penalties for all concerned.
- 225.60 and 225.61 provide more information on clearances,
such as those over sidewalks.
Don't take your
electrical exam twice
Journeyman Electrical Exam Prep | Master Electrician Exam Prep
Learn more about:
How the NEC is arranged
- The first four Chapters of the NEC apply to all installations.
- Article 90 precedes Chapter One, and establishes the authority of the NEC.
- Article 80 follows the body of the NEC; it exists as Annex H. It provides the requirements for administration.
- Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).
- Chapter 8 provides the requirements for communications systems.
- Chapter 9 provides tables.
- The appendices provide mostly reference information.
- Appendix D contains examples that every NEC user should study.
Try your NEC moxy:
- Do you know the difference between bonding and grounding? Hint: Look in the NEC, Article 100.
- Does the NEC refer to grounding incorrectly in any of its articles? Yes! So be careful to apply the Article 100 definitions. Don't ground where you should bond.
- When doing motor load calculations, which Article covers hermetic motors? Answer: While Article 440 covers the application of hermetic motors, it does so only by amending Article 430 because hermetic motors are a special case of motors. For motor load calculations, refer to Article 430.
- Does the NEC provide a voltage drop requirement? Yes! It does so in a special case, which is Article 648 Sensitive Electronic Equipment. But for general applications, it does not provide a requirement; it merely provides a recommendation in a couple of FPNs.
- Take our Code Quizzes.
Remember other applicable codes, rules, standards, and references:
- OSHA's electrical worker safety rules.
- IEEE standards.
- NETA standards.
- NFPA standards.
- International Codes (if applicable to the installation).
- State Codes (if the state has them).
- Local ordinances and permit requirements.
- Local fire codes.
- Manufacturer requirements or guidelines.
- Customer security requirements.
- Industry standards.
- Your company's own internal standards, practices, and procedures.
- Engineering drawing notes.