National Electrical Code Articles and Information
National Electrical Code Top Ten Tips: Article 445 -- Generators
by Mark Lamendola
Based on the 2017 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 445 items we deem most important, based
on the pervasiveness of confusion and the potential costs of same.
- Article 430 also applies. Well, part of it anyhow. Generators must meet the requirementes for motors in 430.14 [445.10]. Those have to do with location factors, such as having adequate ventilation and adequate room for maintenance.
- Generators also, like motors, must be suitable for the locations in which they are installed [445.10]
- Manufacturers are required to provide a nameplate that contains several mandated bits of information [445.11]. This is important for the installer, not because you have to comply with this requirement (the manufacturer does) but because you need this information to do a correct installation job. And there it is, right on the nameplate. Take a photo of that nameplate before installing the generator.
- The overcurrent protection requirements come in five different flavors: constant-voltage generators, two-wire generators, 65V or less, balance sets, and three-wire direct-current generators [445.12].
- You might not be required to provide the overcurrent protection described in 445.12. There's an Exception note at the end of this Section. Basically, if it's safer to run the generator to failure you can let it do that if you provide a supervised alarm and the AHJ signs off on this arrangement.
- The conductors running from the generator to the first distribution devices containing overcurrent protection must have an ampacity of at least 115% the nameplate rating of the generator [445.13(A)].
- You can used tapped conductors from the load side if your installation meets specific circumstances per 445.13 (B). You cannot use tapped conductors for portable generators rated 15.5KW or less where field wiring connections aren't acessible.
- Where field wiring passes through an enclosure, conduit box, or barrier, you must use a bushing to protect the conductors from the edges of the opening [445.16]. Tip: If you drill a hole, deburr it rather than relying on the bushing to also protect from the burrs. Where possible, file sharp edges away. Bushings can wear or pop out (due to vibration or other factors), so don't use them to cover sloppy work. Use them as an additional measure of protection.
- Each generator must have a provision for shutting down the prime mover and it must require a mechanical reset (as opposed to an automatic one) to restart the generator[445.18(B)].
- GFCI protection requirements differ, depending upon whether you have a floating neutral or bonding neutral [445.20].
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.
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