Electrical Codes for Grounding
By Dave Rongey
Summary: Listing of electrical codes for grounding with examples of electrical grounding codes for home electrical wiring.
Electrical Code Definitions for Grounding Home Electrical Systems
Understanding the Importance of Electrical Grounding
Grounding and Bonding
Grounding and Bonding All grounding electrodes that are present at each building or structure served shall be bonded together to form the grounding electrode system.
Code Adoption Information:
The codes shown are examples only and may not be current or accurate for your application or jurisdiction. Contact your local building authority for complete information.
NATIONAL ELECTRICAL CODES
NEC 250.5 Grounding and Bonding
Grounding and Bonding Electrodes include a metal underground water pipe in direct contact with earth for 10 feet or more, a metal frame of a building or structure, a concrete encased electrode or a ground ring
NEC 250.28 Grounding and Bonding Grounding and Bonding
A main bonding jumper or the green bonding screw provided by the panel manufacturer shall be installed in the service panel.
NEC 250.32 Grounding and Bonding
Grounding and Bonding Buildings supplied by a branch circuit or feeder shall have an equipment grounding conductor run with the supply conductors and connected to the grounding electrode system at the separate building.
NEC 250-50 A premise's electrical service shall be connected to a grounding electrode system consisting of a metal underground water pipe in direct contact with earth for 10 feet or more, if available on the premises, and a supplemental electrode (a rod, pipe, or plate electrode.) An additional electrode shall supplement the buried water pipe electrode.
NEC 250.53 Grounding and Bonding Grounding and Bonding
A metal underground water pipe shall be supplemented by an additional electrode, such as an approved rod, pipe or plate electrode.
NEC 250.64 Grounding and Bonding Grounding and Bonding
The grounding electrode conductor shall be continuous, securely fastened and protected from physical damage.
NEC 250.66 Grounding and Bonding Grounding and Bonding
The size of the grounding electrode conductor shall be determined by the size of the service-entrance conductors, per the following chart:
Equivalent Size of Service Entrance Conductor Size
of the Grounding Electrode Conductor
Copper - - - Aluminum - - - Copper Aluminum
..4 AWG... ... ..2............ ........8*........6
..1 AWG..... ...2/0............. . ...6.........4
..2/0 or 3/0.... .4/0 or 250.......4.........2
*The conductor that is the sole connection to a rod, pipe or plate electrode is not required to be larger than #6 AWG copper, however smaller conductors require physical protection.
NEC 250.104 Grounding and Bonding Grounding and Bonding
The interior metal water piping and other metal piping that may become energized shall be bonded to the service equipment with a bonding jumper sized the same as the grounding electrode conductor.
NEC 250.134 Wiring Methods Grounding
All electrical equipment, metal boxes, cover plates, and plaster rings shall be grounded. All switches, including dimmer switches, shall be grounded.
NEC 408.41 Wiring Methods Grounded Conductor
Each grounded conductor shall terminate within a panel board in an individual terminal that is not used for any other conductor.
NEC Code Index
Index for NEC Article Section 250
Grounding and Bonding
The following is a listing of NEC Articles which reference the subject of Grounding and Bonding
General: NEC Article 250.90
Services: NEC Article 250.92
Bonding Conductors and Jumpers: NEC Article 250.102
Bonding for Other Systems: NEC Article 250.94
Bonding for Over 250 Volts: NEC Article 250.97
Bonding of Piping Systems and Exposed Structural Steel: NEC Article 250.104
Bonding Other Enclosures: NEC Article 250.96
Lightning Protection Systems: NEC Article 250.106
Size of the Direct-Current Grounding Electrode Conductor: NEC Article 250.166
Equipment Grounding and Equipment
Equipment Connected by Cord and Plug: NEC Article 250.114
Equipment Fastened in Place (Fixed) or Connected by Permanent Wiring Methods: NEC Article 250.110
Equipment Grounding Conductor Installation: NEC Article 250.120
Identification of Equipment Grounding Conductors: NEC Article 250.119
Identification of Wiring Device Terminals: NEC Article 250.126
Size of Equipment Grounding Conductors: NEC Article 250.122
Specific Equipment Fastened in Place (Fixed) or Connected by Permanent Wiring Methods: NEC Article 250.112
Types of Equipment Grounding Conductors: NEC Article 250.118
Use of Equipment Grounding Conductors: NEC Article 250.121
Definitions: NEC Article 250.2
Clean Surfaces: NEC Article 250.12
Connection of Grounding and Bonding Equipment: NEC Article 250.8
General Requirements for Grounding and Bonding: NEC Article 250.4
Objectionable Current: NEC Article 250.6
Protection of Ground Clamps and Fittings: NEC Article 250.10, Scope : NEC Article 250.1
Grounding Electrode System and Grounding Electrode
Auxiliary Grounding Electrodes: NEC Article 250.54
Common Grounding Electrode: NEC Article 250.58
Grounding Electrode Conductor and Bonding
Jumper Connection to Grounding Electrodes: NEC Article 250.68
Grounding Electrode Conductor Installation: NEC Article 250.64
Grounding Electrode Conductor Material: NEC Article 250.62
Grounding Electrodes 250.52
Grounding Electrode System: NEC Article 250.50
Grounding Electrode System Installation: NEC Article 250.53
Methods of Grounding and Bonding Conductor Connection to Electrodes: NEC Article 250.70
Size of Alternating-Current Grounding Electrode Conductor: NEC Article 250.66
Use of Strike Termination Devices: NEC Article 250.60
Enclosure, Raceway, and Service Cable Connections
Other Conductor Enclosures and Raceways: NEC Article 250.86
Service Raceways and Enclosures: NEC Article 250.80
Methods of Equipment Grounding
Connecting Receptacle Grounding Terminal to Box: NEC Article 250.146
Continuity and Attachment of Equipment
Grounding Conductors to Boxes: NEC Article 250.148
Cord-and-Plug-Connected Equipment: NEC Article 250.138
Equipment Considered Grounded: NEC Article 250.136
Equipment Fastened in Place or Connected by Permanent Wiring Methods (Fixed) Grounding: NEC Article 250.134
Equipment Grounding Conductor Connections: NEC Article 250.130
Frames of Ranges and Clothes Dryers: NEC Article 250.140
Use of Grounded Circuit Conductor for Grounding Equipment: NEC Article 250.142
Alternating-Current Systems of 50 Volts to Less
Than 1000 Volts Not Required to be Grounded: NEC Article 250.21
Alternating-Current Systems to be Grounded: NEC Article 250.20
Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s): NEC Article 250.32
Grounding Separately Derived Alternating-Current Systems: NEC Article 250.30
Grounding Service-Supplied Alternating-Current Systems: NEC Article 250.24
High-Impedance Grounded Neutral Systems: NEC Article 250.36
Main Bonding Jumper and System Bonding Jumper: NEC Article 250.28
Permanently Installed Generators: NEC Article 250.35
Portable and Vehicle-Mounted Generators: NEC Article 250.34
Residential Electrical Code Examples for Grounding
1.A grounding electrode system shall bond to one of the following items if they are available 2003 IRC E3508.1:
a. Metal underground water pipe, unless it is further than five feet from the building b. Concrete encased electrode/footing rebar c. Grounding rod/ring
2. Continuity of the grounding path to interior piping shall not rely on water meters, filters, or similar equipment. 2003 IRC E3508.1.1
3.Interior metal water piping shall be bonded to the service equipment enclosure or the grounded conductor at the service or the grounding electrode when of sufficient size. 2003 IRC E3508.1.1
4.Grounding clamps must be listed for the materials of the grounding electrode and for direct soil burial. 2003 IRC E3511.4
Always contact your local building authority for complete and up to date code information.
More about Electrical Codes for Grounding
Questions about Electrical Codes for Grounding
Questions about Residential Electrical Wiring Codes for EGS Grounding and Bonding
Question from Joseph, a Handyman in Mesquite, Texas.
My question is concerning my breaker box.
Are ground wires allowed on the same buss bar as neutrals wires? Is this a safety concern in a 1981 home build? I have never had any issues so far.
Joseph, Ground wires are allowed on the same buss bar as the neutral wires at the main panel where the main ground wire is located and bonded. If the panel is a sub panel, or any other panel other than the main panel, then the neutral buss and the ground buss must be separated and have separate wires to each of them.
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