Grounding of an electrical system is the intentional connection of a phase conductor or neutral conductor to ground (the earth). This is done for the purpose of limiting the voltage to ground, providing stability, and to control excessive voltage that can occur from utility line surges and lightning.

Not all electrical systems are solidly grounded. The National Electrical Code (NEC) provides requirements for both grounded and ungrounded electrical systems in Article 250, which is the largest article in the NEC^®.

Article 250 is made of several parts including:

• Part I General
• Part II System Grounding
• Part III Grounding electrode system & grounding electrode conductor
• Part IV Enclosure, raceway, and service cable connections
• Part V Bonding
• Part VI Equipment grounding and equipment grounding conductors
• Part VII Methods of equipment grounding conductor connections
• Part VIII DC systems
• Part IX Instruments, meters, and relays
• Part X Grounding of systems and circuits of over 1000 volts

It is important to understand how each part is laid out and which category each part falls under in order to properly apply the article.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC^® edition of NFPA 70.