In this EC&M Tech Talk Randy Barnett, Electrical Codes Manager at NTT Training, first explains the definition found in Article 100 of the NEC® for “Separately Derived Systems.” Once the definition is understood the most common types of these systems are explained. They include distribution transformers and automatic transfer switches. Next, NEC rules are addressed.
Article 250 Grounding and Bonding has specific requirements for the grounding and bonding of separately derived systems. These are found in Sec. 250.30 and consists of three subsections. An overview and some specific wording is examined in each of these subsections. Another commonly installed separately derived system is the Solar Photovoltaic (PV) System. These systems are covered in NEC Article 690. Part V of this article provides requirements for grounding and bonding. The Tech Talk identifies each of the subsection requirements.
Proper installation of separately derived systems is a must. Otherwise, systems and equipment will not operate properly, and safety will be in jeopardy. Use this EC&M Tech Talk to decide if you have such a system and where to find the rules for proper installation.
About the Author
Randy Barnett
CESCP
Randy Barnett is a master electrician, ICC Commercial Electrical Inspector, NFPA-certified Electrical Safety Compliance Professional and has worked as an electrician and technician in nuclear and coal-fired power plants, government nuclear research facilities, and in industrial maintenance and construction. He is the author of Commercial and Industrial Wiring – American Technical Publishers, numerous articles, and the producer of a monthly Tech Talk video series for EC&M Magazine. Randy provides training and program development services for clients such as, NTT Training, ABB, American Polywater, Socomec, and Schneider Electric. Randy can be reached at www.randybarnett.net.