Electrical Codes for Home Electrical Wiring
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Summary: Listing of electrical codes for wiring with examples of electrical wiring codes for home electrical wiring.
Electrical Code Definitions for General Home Wiring Projects
Understanding the importance of Proper Wiring Methods, and wiring according to Electrical Codes
NEC 110.12 Wiring Methods boxes Unused openings in boxes shall be effectively closed. When openings in non-metallic boxes are broken out and not used, the entire box must be replaced.
NEC 110-12 and 370-18 Unused openings in boxes shall be effectively closed. If openings in non-metallic boxes are broken out and not used, the entire box shall be replaced.
NEC 110.14 Wiring Methods conductors and screw terminal Only one conductor shall be installed under a terminal screw. In boxes with more than one ground wire, the ground wires shall be spliced with a wire tail or pig tail attached to the grounding terminal screw of the device.
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 110.14 Underground Wiring - Wire splicing means for direct burial conductors shall be listed for such use.
NEC 110.14 Electrical Services wire conductors Listed anti-oxidant compound shall be used on all aluminum conductor terminations, unless product information specifically states that it is not required.
NEC 110.14 Underground Wiring Underground wiring splicing Wire splicing means for direct burial conductors shall be listed for such use.
NEC 110-14 Only one conductor shall be installed under a terminal screw. In boxes with more than one ground wire, the ground wires shall be spliced with a wire tail ;,; or pig tail attached to the grounding terminal screw.
NEC 110-14 and 300-15 All splices, including ground wires, shall be made with an approved splice cap or wire nut and shall be made in approved electrical boxes or enclosures.
NEC 200.7(C) Wiring Methods wiring Where permanently re-identified at each location where it is
visible and accessible, the conductor with white colored insulation in type NM cable may be used as an ungrounded conductor.
NEC 250-134 and 370-4 Metal boxes, cover plates, and plaster rings shall be grounded. Switches, including dimmer switches, shall be grounded and shall provide a means to ground metal plates.
NEC 300-3 All conductors of the same circuit, including grounded conductors, shall be contained in the same raceway, cable, or trench.
NEC 300-4 In both exposed and concealed locations, where cables are installed through bored holes in joists, rafters, or wood framing members, the holes shall be bored so that the edge of the hole is not less than 1 1/4 inch from the nearest edge of the wood member. Where this distance cannot be maintained, the cable shall be protected from penetration by screws or nails by a steel plate at least 1/16th inch thick and of appropriate length and width.
NEC 314.4 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 300-14 At all boxes there shall be a minimum wire length of 6 inches, with at least 3 inches outside the box.
NEC 314.17 Wiring Methods boxes: Unused openings in boxes shall be effectively closed. When openings in non-metallic boxes are broken out and not used, the entire box must be replaced.
NEC 314.17 Wiring Methods nm wire outer jacket in box outer jacket of NM cable shall extend into the box a minimum of 1 inch.
NEC 314.19 Wiring Methods junction boxes accessible Junction boxes shall be installed so that the wiring contained in them can be rendered accessible without removing any part of the building.
NEC 300-22 Type NM cable shall not be installed in spaces used for cold air returns, however NM is permitted to pass through perpendicular to the long dimension of such spaces.
NEC 314.23 Wiring Methods boxes All electrical boxes shall be rigidly secured to the building structure.
NEC 314.25 Wiring Methods lighting boxes In completed installations, each box shall have a lamp-holder, canopy or device with an appropriate cover plate.
NEC 314.27 Wiring Methods ceiling fan boxes: When boxes are used as the sole support for a ceiling paddle fan, they shall be listed and labeled for such use
NEC 334.3 Wiring Methods nm wire support Type NM (nonmetallic) cable shall be secured at intervals not exceeding 1.4 m [4.5'] and within 300 mm [12inches] of each box.
NEC 336-18 and 370-17 Type NM (nonmetallic) cable shall be secured at intervals not exceeding 4 1/2 feet and within 12 inches of each box. However, if a single gang device box without a clamp is used, the cable shall be secured within 8 inches of the box.
NEC 370-16 The volume of electrical boxes shall be sufficient for the number of conductors, devices, and cable clamps contained within the box.
Nonmetallic boxes are marked with their cubic inch capacity.
Use the following table to properly calculate box size:
Conductor Size .................................14 gauge .....................12 gauge
For each separate insulated wire ..........2 cu in ........................2.25 cu in
All ground wires (combined) .................2 cu in ........................2.25 cu in
For each device (switch/receptacle) ......4 cu in ........................4.5 cu in
All internal cable clamps (combined) .....2 cu in ........................2.25 cu in
Sample Box Fill Calculation:
Four #14/2 with ground cables:
Eight insulated wires..............16 cubic inches
All ground wires......................2 cubic inches
One switch....................... .....4 cubic inches
One receptacle................... ...4 cubic inches
All clamps....................... ......2 cubic inches
Total box volume required.......28 cubic inches
NEC 370-17 The outer jacket of NM cable shall extend into the box a minimum of 1/4 inch.
NEC 370-23 All electrical boxes shall be securely supported by the building structure.
NEC 370-25 and 410-12 In a completed installation, all outlet boxes shall have a cover, canopy for a lighting fixture, or device with an appropriate plate.
NEC 370-27 When boxes are used as the sole support for a ceiling paddle fan, they shall be listed and labeled for such use.
NEC 370-29 Do not conceal junction boxes in walls, ceilings, or non-accessible attics and under-floor areas.
NEC 404.9 Wiring Methods Grounding: All electrical equipment, metal boxes, cover plates, and plaster rings shall be grounded. All switches, including dimmer switches, shall be grounded.
Residential Electrical Code Examples for Wiring