Class 4 is a new term that will be part of the 2023 edition of the National Electrical Code (NEC). Class 4 is defined in a new article 726. Article 726 is part of chapter 7 which is the section of the NEC that deals with special conditions. Class 4 systems are referred to as “Fault Managed Power Systems” (FMPS). These systems are not power limited and can deliver hundreds or thousands of watts of power. The voltage can be up to 450V AC or DC which sounds dangerous.  However, these systems intelligently limit the amount of energy that can go into a fault. Limiting the fault energy mitigates the risk of shock or fire and allows the installation of Class 4 circuits using methods like power-limited circuits. VoltServerTM was the pioneer of fault managed power systems and has over 1,000 installations using this technology under existing electric codes supporting applications in wireless communications, intelligent buildings, and controlled environment agriculture (CEA).