ARTICLE 250 Grounding and Bonding Mike （第250条接地和等电位连接迈克）.pdfVIP

ARTICLE 250 Grounding and Bonding INTRODUCTION TO ARTICLE 250—GROUNDING AND BONDING No other article can match Article 250 for misapplication, violation, and misinterpretation. Terminology used in this article has been a source for much confusion, but that has improved during the last few NEC revisions. It’s very important to understand the difference between grounding and bonding in order to correctly apply the provisions of Article 250. Pay careful attention to the definitions that apply to grounding and bonding both here and in Article 100 as you begin the study of this important article. Article 250 covers the grounding requirements for providing a path to the earth to reduce overvoltage from lightning, and the bonding requirements for a low-impedance fault current path back to the source of the electrical supply to facilitate the opera- tion of overcurrent devices in the event of a ground fault. Over the past five Code cycles, this article was extensively revised to organize it better and make it easier to understand and implement. It’s arranged in a logical manner, so it’s a good idea to just read through Article 250 to get a big picture view—after you review the definitions. Next, study the article closely so you understand the details. The illustrations will help you under- stand the key points. PART I. GENERAL 250.1 Scope. Article 250 contains the following grounding and bonding requirements: (1) What systems and equipment are required to be grounded. (3) Location of grounding connections. (4) Types of electrodes and sizes of grounding and bonding conductors. (5) Methods of grounding and bonding. 250.2 Definitions. Figure 250–1 Bonding Jumper, Supply-Side. A conductor on the supply side or within a service or separately derived system