1. Conductor Material and Specifications
- Copper Conductors: Copper is the primary material for internal wiring due to its superior conductivity, stability, and resistance to oxidation. Aluminum is generally avoided due to lower conductivity and higher risk of thermal expansion issues.
- Wire Gauge: The cross-sectional area of wires must match the appliance’s power requirements. For example:
- High-power appliances (e.g., air conditioners) require thicker wires (e.g., 4–6 mm² for 4500W+ units).
- Low-power devices (e.g., small electronics) may use 0.5–1.5 mm² wires.
- Flexibility: Multi-strand soft wires (BVR type) are preferred for internal connections to accommodate bending and vibration, while single-core hard wires (BV type) are used for fixed installations.
2. Insulation and Protection
- Flame Retardancy: Insulation materials must meet flame-retardant standards (e.g., ZC-RV series) to delay fire spread in case of overheating.
- Temperature Resistance: Wires in high-temperature zones (e.g., near motors or heating elements) must use heat-resistant insulation (e.g., silicone or Teflon).
- Mechanical Protection: Critical connections (e.g., motor terminals) require pre-insulated terminals or heat-shrink tubing to prevent abrasion and short circuits.
3. Connection Methods
- Terminal Connections:
- Wire ends must be securely crimped or soldered to terminals. Loose connections can cause arcing, overheating, or fires.
- U-shaped or ring terminals are recommended for screw-type connections to ensure full contact and prevent slippage.
- Splicing:
- Splices must use methods like the “cross-twist” technique, followed by soldering and double-layer insulation (fireproof tape + electrical tape).
- No joints are allowed inside conduits; all splices must be housed in junction boxes.
- Torque Control: Terminal screws should be tightened with calibrated tools to avoid over-tightening (damage) or under-tightening (loose contacts).
4. Color Coding and Identification
- Standard Colors:
- Live (Phase): Red, brown, or yellow.
- Neutral: Blue or black.
- Ground (Earth): Green-yellow stripes.
- Labeling: Wires and terminals must be clearly labeled to prevent misconnections, especially in complex circuits.
5. Grounding and Safety
- Mandatory Grounding: All metal appliance casings must be connected to a dedicated ground wire (≥2.5 mm²) to prevent electric shock. Grounding resistance should be <4Ω.
- Isolation: Ground wires must never share terminals with neutral wires to avoid “neutral-to-ground” faults.
- Leakage Protection: High-power appliances (e.g., water heaters) require dedicated circuits with residual current devices (RCDs).
6. Load and Overload Protection
- Current Rating: Wires must handle at least 125% of the appliance’s rated current to prevent overheating. For example, a 10A load requires a wire rated for ≥12.5A.
- Circuit Breakers: Integrated overload protection (e.g., thermal cutoffs or fuses) is mandatory in appliances with high inrush currents (e.g., compressors).
7. Testing and Certification
- Compliance Standards:
- IEC 60335: Global safety standard for household appliances.
- GB Standards (China): e.g., GB 2099.7-2024 for plugs and connectors.
- UL/CSA (North America): Certification for insulation and fire safety.
- Quality Checks:
- Continuity tests, insulation resistance tests (>1 MΩ), and hi-pot (high-voltage) tests are required during manufacturing.
Key Risks to Avoid
- Overloading: Using undersized wires for high-power devices can cause insulation melting and fires.
- Poor Workmanship: Inadequate crimping, uninsulated joints, or mixed wire types (e.g., copper-aluminum) lead to corrosion and failures.
- Environmental Exposure: Wires in humid areas (e.g., kitchens) must have moisture-resistant insulation and sealed connectors.
For detailed implementation guidelines, refer to appliance-specific manuals and regional electrical codes (e.g., NEC, IEC, or GB standards).
Post time: Apr-15-2025