AWG 线规图表
NEC 表 314.16(B) 电气接线盒填充计算的导体容积容许量。
| AWG 尺寸 | Volume (cu.in.) | Volume (mm\u00B3) | Max Amps | 应用 |
|---|---|---|---|---|
| 18 AWG | 1.50 | 24.6 | 7A | Thermostat wiring, Doorbell circuits |
| 16 AWG | 1.75 | 28.7 | 10A | Extension cords, Light fixtures |
| 14 AWG | 2.00 | 32.8 | 15A | 15-amp circuits, Lighting circuits |
| 12 AWG | 2.25 | 36.9 | 20A | 20-amp circuits, Kitchen outlets |
| 10 AWG | 2.50 | 41.0 | 30A | 30-amp circuits, Electric dryers |
| 8 AWG | 3.00 | 49.2 | 40A | 40-amp circuits, Electric ranges |
| 6 AWG | 5.00 | 82.0 | 55A | 55-amp circuits, Sub-panel feeders |
导体容积详情
18 AWG 导体
18 AWG conductors are typically used for low-voltage applications and control wiring.
容积容许量: 1.5 cu.in. (24.6 mm\u00B3)
最大载流量: 7 amps
应用: Thermostat wiring, Doorbell circuits, Low-voltage controls
16 AWG 导体
16 AWG conductors are used for light-duty circuits and appliance cords.
容积容许量: 1.75 cu.in. (28.7 mm\u00B3)
最大载流量: 10 amps
应用: Extension cords, Light fixtures, Small appliances
14 AWG 导体
14 AWG is the minimum size for standard 15-amp household circuits per NEC.
容积容许量: 2 cu.in. (32.8 mm\u00B3)
最大载流量: 15 amps
应用: 15-amp circuits, Lighting circuits, General outlets
12 AWG 导体
12 AWG conductors are required for 20-amp circuits and kitchen/bathroom outlets.
容积容许量: 2.25 cu.in. (36.9 mm\u00B3)
最大载流量: 20 amps
应用: 20-amp circuits, Kitchen outlets, Bathroom GFCIs, Garage circuits
10 AWG 导体
10 AWG conductors are used for 30-amp circuits such as dryers and water heaters.
容积容许量: 2.5 cu.in. (41 mm\u00B3)
最大载流量: 30 amps
应用: 30-amp circuits, Electric dryers, Water heaters, AC units
8 AWG 导体
8 AWG conductors support 40-amp circuits for ranges and large appliances.
容积容许量: 3 cu.in. (49.2 mm\u00B3)
最大载流量: 40 amps
应用: 40-amp circuits, Electric ranges, Large AC units, Hot tubs
6 AWG 导体
6 AWG conductors are used for 55-amp circuits and sub-panel feeders.
容积容许量: 5 cu.in. (82 mm\u00B3)
最大载流量: 55 amps
应用: 55-amp circuits, Sub-panel feeders, Large appliances, EV chargers
了解 NEC 表 314.16(B)
American Wire Gauge is a standardized conductor sizing system used to describe the diameter of nonferrous electrical wire. In box fill work, AWG matters because each conductor size is assigned a specific cubic-inch allowance under NEC 314.16, which means wire size directly changes the minimum box volume required.
A junction box is an enclosure for conductor splices, taps, or terminations, and box fill refers to the method of checking whether that enclosure is large enough for the wiring arrangement. The wire gauge chart supports that process by translating the conductor label on the cable or device wiring into the volume allowance the code expects you to count.
A cable assembly refers to multiple insulated conductors grouped in one sheath, while a wire harness is an organized bundle secured for routing and protection. Those definitions matter because electricians often start with a cable label, but box-fill accuracy depends on understanding the individual conductor sizes hidden inside that cable package.
A crimp is a compression-based electrical termination that joins a conductor to a connector barrel or splice sleeve. Crimped terminations and circular connectors show why conductor size cannot be treated as an abstract number: the wire gauge affects routing density, bend behavior, and enclosure packaging decisions throughout the system.
Author: Hommer Zhao is a General Manager and Wire Harness Engineer at WIRINGO. His background in wire selection, connector integration, and conductor packaging is directly relevant to how AWG size translates into box-fill volume and installation decisions.
如何使用线规图表
Start by identifying the actual branch-circuit or feeder conductor size installed in the box. Then match that AWG size to the corresponding volume allowance before counting device yokes, internal clamps, support fittings, grounding conductors, and any special conditions that affect the final fill total.
重要说明
The chart is a reference tool, not a substitute for the governing code table or for installation judgment. Conductors with the same ampacity application can still require different box-fill allowances, and crowded enclosures usually create problems long before they look obviously overfilled from the outside.
Authoritative references
- American wire gauge explains the conductor size system used on this page.
- National Electrical Code provides the governing box-fill framework.
- Crimp (joining) adds context for wire-to-terminal and splice packaging decisions.
- Circular connector shows another common high-density termination context where conductor size matters.
- Wire harness and cable harness provide broader conductor-packaging context.
- IPC (electronics), IATF 16949, and ISO 9001 provide quality-system context for repeatable electrical manufacturing processes.
Frequently Asked Questions
What does AWG mean in a box fill calculation?
AWG means American Wire Gauge, the conductor sizing system commonly used in the United States. In box fill work, the AWG size determines the cubic-inch allowance assigned to each countable conductor.
Why does a larger conductor require more box volume?
Larger conductors have greater insulation diameter, stiffer bending behavior, and more physical bulk in the enclosure. NEC box fill allowances scale with conductor size so the box remains workable and safe.
Does ampacity replace the box fill table?
No. Ampacity helps explain application suitability, but box fill uses dedicated volume allowances. You still need the correct NEC conductor-fill table value for the final enclosure calculation.
Are all grounding conductors counted separately?
No. Equipment grounding conductors are counted together as a single conductor allowance based on the largest grounding conductor present, even when several grounds enter the box.
How should I use this chart with a box fill calculator?
Match the installed conductor size to its chart entry, note the cubic-inch allowance, count every eligible conductor and fitting, and then compare the total required volume with the actual box capacity.