electrical box parts
The following is a detailed classification, functions, and technical descriptions of **Electrical Box Parts**, with
Chinese-English translations provided:
I. Classification of Core Components of Electrical Boxes
1. Electrical Box Body
| Type | Material | Characteristics and Application Scenarios | Standards |
| Square Box | PVC/Metal | Universal type, used for sockets and switches (e.g., 4x4 inches) | NEMA 1/3R in the United States, GB 7251 in China |
| Round Box | Cast Iron/Plastic | Fixing for lamps and ceiling fans (e.g., Octagon Box) | UL 514C |
| Ultra-thin Box | Cold-rolled Steel | Embedded installation on the wall (thickness ≤ 1.5 inches) | NEC 314.29 |
| Waterproof Box | Polycarbonate | Outdoor/wet environment (IP66/IP67 protection) | IEC 60529 |
2. Covers & Plates
- **Blank Cover**
- Material: Plastic/Metal
- Function: Enclose the box body and reserve screw holes
- Special Types:
- **Decorative Cover**: With patterns, used for home aesthetics
- **Hinge Cover**: A flip design for convenient maintenance
- **Switch Plate**
- Size: Single gang (1-Gang), double gang (2-Gang) up to quadruple gang
- Material: ABS/Tempered glass (scratch-resistant)
- Standards: CSA C22.2 No. 53 in the United States, GB 16915.1 in China
3. Connectors & Openings
| Component Name | Function Description | Common Specifications |
| Knockout | Removable round/rectangular hole for threading wires | 1/2 inch, 3/4 inch NPT threads |
| Grommet | Rubber sealing ring to protect wires and prevent water ingress | Suitable for cable diameters of 5-16mm |
| Hub | Exclusive for metal boxes, connecting conduits (Conduit) | Standard threads from 1/2 inch to 2 inches |
4. Fixing and Installation Accessories
- **Box Clamp**
- Used to fix the box on wooden beams/light steel keels
- Types: Single Ear, Double Ear
- **Expansion Anchor**
- Special for installation on concrete walls, with a load-bearing capacity of ≥ 30kg
- Material: Stainless steel/galvanized steel
II. Safety and Grounding Components
1. Grounding System
- **Grounding Screw**
- Essential for metal boxes, connecting the ground wire (Green Wire)
- Specification: #10-32 UNC threads
- **Grounding Jumper**
- Ground connection between the metal box and the extension, which needs to meet the AWG 12 standard
2. Anti-short-circuit Components
- **Insulating Bushing**
- Protects against cutting and insulates the wire-passing holes of metal boxes, made of nylon
- **Cable Clamp**
- Fixes the cable to prevent short circuits caused by looseness, such as Romex cable clamps
III. Special Function Components
1. Extension and Wire Splitting Components
- **Wire Connector**
- Types: Twist-on (Wire Nut), Push-in
- Capacity: 2-12 wires of AWG 14-10
- **Terminal Block**
- Used in industry, supporting wire splitting for large currents, such as the Phoenix Contact series
2. Sealing and Protection Components
- **Waterproof Tape**
- Made of butyl rubber, with an IP67 sealing rating
- **Silicone Gasket**
- Temperature resistance from -50°C to +200°C, exclusive for outdoor boxes
IV. Installation Tools and Accessories
| Tool Name | Purpose Description | Recommended Brands |
| Box Cutter | Cutting openings in gypsum boards with an accuracy of ±1mm | Milwaukee |
| Torque Screwdriver | Fixing screws to the standard torque (e.g., 6-8 lb·in) | Klein Tools |
| Circuit Tester | Detecting grounding continuity and voltage (e.g., Fluke 117) | Fluke |
V. Purchase and Installation Precautions
1. **Material Compatibility**
- Metal boxes need to be matched with **me
