Section 408.6: A Brand-New Addition to the 2020 NEC
NEC section 408.6 states: Switchboards, Switchgear, and Panelboards shall have a short-circuit current rating (SCCR) not less than the available fault current. In other than one- and two-family dwelling units, the available fault current and the date the calculation was performed shall be field marked on the enclosure at the point of supply. The marking shall comply with 110.21(B)(3).
Making NEC 408.6 Simple
This new Code Section simply means that electrical panels including main-breaker and main-lug type panels and switchboards & switchgear equipment must be rated (in amps) to withstand the high levels of current that will flow should a short-to-ground or other fault occur at the equipment. In ALL locations other than dwelling units, that anticipated fault current must be marked on the equipment enclosure near where the supply conductors enter in, along with the date that the calculation producing that number was performed. The new Code Section also says the markings on the equipment must comply with 110.21(B)(3). Section 110.21(B)(3) tells us that markings must be sufficiently durable to withstand the environment.
The 2020 NEC now recognizes that GFCI protection for mobile and manufactured homes must be equal to that of stick-built and modular type dwellings. Construction Codes, in general, have always been less restrictive for mobile-type dwellings. This may be because mobile homes are often titled with the Motor Vehicle Department, and this type of housing is built, inspected, tested, and listed off-site at a manufacturing plant.
The primary intent of this discussion is to explain how overcurrent protection devices are determined for single motor branch-circuits. References will be taken from the 2020 National Electrical Code (NEC). These references will apply to general single motor applications for a continuous duty NEMA Design B energy efficient motor, unless otherwise noted.
The 2020 Code Making Panel has introduced a new and unprecedented Code section for this 2020 Code cycle that may prove controversial once time allows this directive to play out.
This new requirement found in Section 680.4 of the 2020 NEC allows the Authority Having Jurisdiction (AHJ) to return to a home or business for follow-up inspection(s) even after the swimming pool, fountain, or similar has passed final inspection, and the job is complete.
It seems like we just started using the 2017 National Electrical Code, and now the 2020 version is available. There have been significant changes, accomplished through public comment and hard work by the Code Making Panels and others. What are some of the important changes that will affect installers, electricians, and AHJ’s? We are eager to know what has been changed. Just as importantly, when can we reasonably expect that the new version of the Code will be adopted? Each state must decide when to move to the next edition of the NEC.
Changes to the 2020 NEC include the addition of several paragraphs in section 430.122. These changes will help the user to determine the correct ampacity for conductors used with power conversion equipment. The Adjustable Speed Drive is one type of power conversion equipment that provides a means of adjusting the speed of an electric motor, 100. A Variable Frequency Drive, VFD, is an adjustable speed drive that controls the speed, the RPM, of a motor by controlling the frequency and voltage supplied to a motor. The changes made in 430.122 Conductors – Minimum Size and Ampacity apply to Adjustable Speed Drive Systems.
Section 250.25 is brand new for the 2020 Code cycle. It has been created to establish grounding and bonding rules for add-on disconnects, such as a PV system disconnect acting as that PV system’s service equipment, when the disconnect is attached to conductors on the supply side (meaning before the main cut-off) of the utility service disconnect.
Section 230.82 provides electricians with a list of equipment/systems that can legally connect to the conductors on the supply side of an electrical system serving a home or business. The new Section 250.25 outlines grounding and bonding rules for a disconnect serving just such an add-on system.
There will be four new article additions to the 2020 NEC:
1. Article 242 Overvoltage Protection
2. Article 311 Medium Voltage Conductors and Cable
3. Article 337 Type P Cable
4. Article 800 General Requirements for Communications Systems
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