National Electrical Code (NEC) Definitions on Grounding and Bonding

Importance of Terminology

• Essential for effective communication in grounding and bonding
• Focus on Article 100 for definitions

Key Definitions

Ground

• Defined as "the earth"
• Connection to earth made via grounding electrodes

Grounding Electrode

• Conducting object for direct electrical connection to earth
• Examples: ground rod, grounding grid, building structural steel, water pipe
• Multiple electrodes connected to form a Grounding Electrode System

Grounding Electrode System

• All grounding electrodes at a site connected together

Grounding Electrode Conductor

• Connects system neutral or grounded phase to the grounding electrode system

Grounded vs. Ungrounded

• Grounded: Connected to earth or an extended earth connection
• Ungrounded: Not connected to ground

Grounded Conductor

• Conductor intentionally connected to earth, often referred to as "neutral"

Ungrounded Conductor

• Circuit conductor not intentionally connected to earth, usually phase conductors

Grounding Conductor

• Connects equipment or grounded circuit of a wiring system to grounding electrode/system

Bonding and Jumpers

Bonding

• Establishes electrical continuity and conductivity

Bonding Conductors/Jumpers

• Ensure required electrical conductivity between metal parts
• Main Bonding Jumper: Connects grounded circuit conductor to equipment grounding conductor or supply side bonding jumper at service
• Supply Side Bonding Jumper: For supply side of service or within service equipment enclosures

Transformers

• Separately derived systems and bonding impact transformer operation
• Delta Y Grounded Transformer: Example of separately derived system

Generator Bonding

• Establish a separately derived system by bonding neutral and enclosure
• Impacts transfer switch requirements (3-pole vs. 4-pole)

Types of Grounding Systems

Solidly Grounded vs. Impedance Grounded Systems

• Solidly Grounded: Direct connection to earth without resistor or impedance
• Impedance Grounded: Connection to earth through an impedance
• Ungrounded: No connection to ground

Objectionable Currents

• Current on ground path during non-faulted conditions
• Rule changes to address motion sensor switches and their power requirements

Final Remarks

• Critical use of correct terminology for effective communication and system accuracy
• Understanding grounding and bonding is essential for compliance and safety.