CQD Spotlight features questions and answers from NECA and ELECTRICAL CONTRACTOR’s Code Question of the Day program. Whether you’re a seasoned contractor, an apprentice or simply a National Electrical Code enthusiast, you’ll gain knowledge with a nod to the legacy of Charles M. “Charlie” Trout, a true NEC legend.
From the archives— October 15, 2024
In an AC disconnect safety switch, a surge protection device is being installed. The nameplate is not clear if the lugs are rated for two wires. Much like a residential panelboard, is the use of a wire nut splice permitted?
Sections: 242.12, 242.14, 242.16, 242.28 and 242.30 provide guidance on the installation and connection of SPDs. Additionally, the manufacturer installation instructions should be consulted. Similar to the National Electrical Code, the installation
instructions may have specific requirements on connection and lead length as these can impact the overall performance of the SPD.
From the archives— April 29, 2022
Good day, I heard that the NEC requires surge protection for residential services. Does this apply to installations that fall under the 2017 NEC? Thanks for the help with this.
Thanks for participating. Surge protection is not required for dwelling unit services under the 2017 NEC. There is a change, however, in the 2020 NEC Section 230.67 that requires surge protection for dwelling unit services. The requirement
recognizes that a Type 1 or Type 2 surge protective device must be installed. It is always a good idea to verify with the authority having jurisdiction any local requirements that may also be applicable.
From the archives— March 22, 2022
Hello Code friends, can a Type 2 surge protective device be connected to the line side of the service disconnecting means and overcurrent protective device?
Thanks for the question. No, Type 2 surge protective devices are not permitted on the line side of the service overcurrent protective device. See the definition of surge protective device (SPD) in Article 100 and Section 242.12(A) and (B). Section 242.14 provides requirements for Type 2 surge protective device locations.
From the archives— January 13, 2021
Dear Code Question of the Day, this is a really informative NEC forum. Are surge protective devices required to be listed?
Thanks for the question and the comments. Yes, surge protective devices are required to be listed. See Section 242.8 in the 2020 NEC and 285.6 in the 2017 NEC. There are no exceptions to this requirement.
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The NEC has seen an expansion of surge protection requirements over the last few Code cycles. A surge protective device (SPD) provides protection of equipment from transient voltages. It would be a mistake to think that the SPD is only there to protect life safety equipment. We must remember the purpose of the NEC. Section 90.2 of the NEC reminds us of the use and application of the Code. Section 90.2(A), Practical Safeguarding, tells us that the purpose of the NEC is the practical safeguarding of persons and property from hazards arising from the use of electricity. Requirements found in the NEC do not only have to protect personnel. Protection of property is the area where the SPD does best.
This video demonstrates the protection offered by an SPD. It’s important that we understand the protection provided and convey that to end-users, as the placement of these devices should transcend the requirements of the Code seeing them applied for protection of property.
Proper application of an SPD is critical for protection. This video demonstrates the significance of lead length. Too often, these devices are not installed such that the lead lengths are kept short and straight. Misapplication of the SPD can leave the equipment with no protection at all.
The following are key sections of the 2023 NEC where you can find SPD requirements:
- 230.67—Service equipment
- 215.18—Feeders
- 225.42—Outside branch circuits and feeders
- 409.70—Industrial control panels
- 501.35—Class I locations and 502.35 - Class II, Div. 1 and 2
- 620.51—Elevators
- 645.18—Critical operation data systems
- 670.6—Industrial machinery
- 695.15—Fire pumps
- 700.8—Life safety systems
- 708.20—COPS
