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Section E3406 Electrical Conductors and Connections
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This section provides general requirements
for conductors, connections and splices. These requirements
do not apply to conductors that form an integral part of
equipment, such as motors, appliances and similar equipment,
or to conductors specifically provided for elsewhere in
Chapters 34 through 43. (310.1)
Conductors used to conduct
current shall be of copper except as otherwise provided in
Chapters 34 through 43. Where the conductor material is not
specified, the material and the sizes given in these chapters
shall apply to copper conductors. Where other materials are
used, the conductor sizes shall be changed accordingly. (110.5)
The minimum size of
conductors for feeders and branch circuits shall be 14 AWG
copper and 12 AWG aluminum. The minimum size of service
conductors shall be as specified in Chapter 36. The minimum
size of Class 2 remote control, signaling and power-limited circuits
conductors shall be as specified in Chapter 43.
[310.106(A)]
Except where otherwise
permitted in Sections E3605.1 and E3908.9, and E4303,
current-carrying conductors shall be insulated. Insulated conductors
shall have insulation types identified as RHH, RHW,
RHW-2, THHN, THHW, THW, THW-2, THWN, THWN-2,
TW, UF, USE, USE-2, XHHW or XHHW-2. Insulation types
shall be approved for the application. [310.106(C), 310.104]
Circuit conductors that are
connected in parallel shall be limited to sizes 1/0 AWG and
larger. Conductors in parallel shall: be of the same length; consist
of the same conductor material; be the same circular mil
area and have the same insulation type. Conductors in parallel
shall be terminated in the same manner. Where run in separate
raceways or cables, the raceway or cables shall have the same
physical characteristics. Where conductors are in separate
raceways or cables, the same number of conductors shall be
used in each raceway or cable. [310.10(H)]
All conductors of
the same circuit and, where used, the grounded conductor and
all equipment grounding conductors and bonding conductors
shall be contained within the same raceway, cable or cord.
[300.3(B)]
Terminals
and splicing connectors shall be identified for the material of
the conductors joined. Conductors of dissimilar metals shall
not be joined in a terminal or splicing connector where physical
contact occurs between dissimilar conductors such as copper
and aluminum, copper and copper-clad aluminum, or
aluminum and copper-clad aluminum, except where the
device is listed for the purpose and conditions of application.
Materials such as inhibitors and compounds shall be suitable
for the application and shall be of a type that will not
adversely affect the conductors, installation or equipment.
(110.14)
Connectors and terminals for conductors that are more finely stranded than Class B and Class C stranding as shown in Table E3406.9, shall be identified for the specific conductor class or classes. (110.14)
| CONDUCTOR SIZE | NUMBER OF STRANDS | |||
| Copper | Aluminum | |||
| AWG or kcmil | mm2 | Class B | Class C | Class B |
| 24-30 | 0.20-0.05 | a | - | - |
| 22 | 0.32 | 7 | - | - |
| 20 | 0.52 | 10 | - | - |
| 18 | 0.82 | 16 | - | - |
| 16 | 1.3 | 26 | - | - |
| 14-2 | 2.1-33.6 | 7 | 19 | 7b |
| 1-4/0 | 42.4-107 | 19 | 37 | 19 |
| 250-500 | 127-253 | 37 | 61 | 37 |
| 600-1000 | 304-508 | 61 | 91 | 61 |
| 1250-1500 | 635-759 | 91 | 127 | 91 |
| 1750-2000 | 886-1016 | 127 | 271 | 127 |
- Number of strands vary.
- Aluminum 14 AWG (2.1 mm2) is not available.
- With the permission of_Underwriters Laboratories, Inc., this material is reproduced from UL Standard 486A-B, Wire Connectors, which is copyrighted by Underwriters Laboratories, Inc., Northbrook, Illinois. While use of this material has been authorized, UL shall not be responsible for the manner in which the information is presented, nor for any interpretations thereof.
Connection of conductors to terminal
parts shall be made without damaging the conductors and
shall be made by means of pressure connectors, including setscrew
type, by means of splices to flexible leads, or for conductor
sizes of 10 AWG and smaller, by means of wire binding
screws or studs and nuts having upturned lugs or the
equivalent. Terminals for more than one conductor and terminals
for connecting aluminum conductors shall be identified
for the application. [110.14(A)]
Conductors shall be spliced or joined with
splicing devices listed for the purpose. Splices and joints and
the free ends of conductors shall be covered with an insulation
equivalent to that of the conductors or with an insulating
device listed for the purpose. Wire connectors or splicing
means installed on conductors for direct burial shall be listed
for such use. [110.14(B)]
Conductors in raceways shall be
continuous between outlets, boxes, and devices and shall
be without splices or taps in the raceway.
Exception: Splices shall be permitted within surface-mounted
raceways that have a removable cover.
[300.13(A)]
The continuity of a
grounded conductor in multiwire branch circuits shall not
be dependent on connection to devices such as receptacles
and lampholders. The arrangement of grounding connections
shall be such that the disconnection or the removal of
a receptacle, luminaire or other device fed from the box
does not interfere with or interrupt the grounding continuity.
[300.13(B)]
Where conductors are to be spliced, terminated or
connected to fixtures or devices, a minimum length of 6
inches (152 mm) of free conductor shall be provided at
each outlet, junction or switch point. The required length
shall be measured from the point in the box where the conductor
emerges from its raceway or cable sheath. Where
the opening to an outlet, junction or switch point is less
than 8 inches (200 mm) in any dimension, each conductor
shall be long enough to extend at least 3 inches (75 mm)
outside of such opening. (300.14)
The continuity
of a grounded conductor shall not depend on connection to a
metallic enclosure, raceway or cable armor. [200.2(B)]
The connection of equipment grounding conductors,
grounding electrode conductors and bonding jumpers shall be
in accordance with Sections E3406.13.1 and E3406.13.2.
Equipment grounding
conductors, grounding electrode conductors, and bonding
jumpers shall be connected by one or more of the following
means:
- Listed pressure connectors.
- Terminal bars.
- Pressure connectors listed as grounding and bonding equipment.
- Exothermic welding process.
- Machine screw-type fasteners that engage not less than two threads or are secured with a nut.
- Thread-forming machine screws that engage not less than two threads in the enclosure.
- Connections that are part of a listed assembly.
- Other listed means. [250.8(A)]
Connection devices
or fittings that depend solely on solder shall not be used.
[250.8(B)]
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