Article 242 Overvoltage Protection.

Article 242 is new in the 2020 NEC and was made from combining previous Article 280 Surge Arresters, Over 1000 Volts, and Article 285 Surge-Protective Devices (SPDs), 1000 Volts or Less.
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Article 242 is new in the 2020 NEC and was made from combining previous Article 280 Surge Arresters, Over 1000 Volts, and Article 285 Surge-Protective Devices (SPDs), 1000 Volts or Less.

Code Change Summary: New article.

Article 242 is new in the 2020 NEC® and was made from combining previous Article 280 Surge Arresters, Over 1000 Volts, and Article 285 Surge-Protective Devices (SPDs), 1000 Volts or Less.

Having both previous NEC® articles combined into one and located immediately after Article 240 (Overcurrent Protection) makes sense and improves the overall usability of the NEC®.

Article 242 is split into the following three parts:

Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.

2017 Code Language:

The 2020 requirements in Article 242 were previously found in Article 280 Surge Arresters, Over 1000 Volts, and Article 285 Surge-Protective Devices (SPDs), 1000 Volts or Less.

2020 Code Language:

N 242.1 Scope. This article provides the general requirements, installation requirements, and connection requirements for overvoltage protection and overvoltage protective devices. Part II covers surge-protective devices (SPDs) permanently installed on premises wiring systems of not more than 1000 volts, nominal, while Part III covers surge arresters permanently installed on premises wiring systems over 1000 volts, nominal.

Informational Note: Article 242 combines and replaces Articles 280 and 285 in NFPA 70-2017.

242.8 Listing. An SPD shall be a listed device.

242.10 Short-Circuit Current Rating. The SPD shall be marked with a short-circuit current rating and shall not be installed at a point on the system where the available fault current is in excess of that rating. This marking requirement shall not apply to receptacles.

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Article 242 Overvoltage Protection.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Based on the 2020 NEC, which of the following is true?

A: New Article 242 Part II applies to Surge-Protective Devices, rated over 1000 volts.
B: Article 242 Part III applies to Surge arrestors under 1000 volts.
C: The SPD shall be installed at a point on the system where the available fault current is in excess of its marked short-circuit current rating.
D: An SPD shall be a listed device.
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