Article 712 of the National Electrical Code (NEC) provides the requirements for any power distribution system that consists of more than one interconnected direct current (DC) power source that supplies loads either directly or through DC-AC inverters or DC-DC converters. These systems are known as DC microgrids.
As with any situation involving multiple power sources for a structure or site, you must have a directory denoting all the DC power sources [712.10]. This requirement should perhaps be in Article 110 or Article 230 instead of being repeated so much in Chapter 7. The reason for this is so that first responders can shut down or isolate dangerous energy sources prior to entering a structure.
In a similar vein, the output of each DC source must have a disconnecting means [712.34]. It must be lockable in the open position — a fundamental requirement that facilitates lockout/tagout (LOTO).
These systems must be grounded per Part VIII of Article 250, “Direct-Current Systems.” Article 712 does not specifically mention a requirement for bonding all noncurrent-carrying metallic parts (e.g., panel enclosures), but that is also a requirement [250, Part V].
Overcurrent protection is required [712, Part V].
