水管电线管材详解 (Pipe & Wire Materials Guide)
1. Water Pipe Materials: PPR vs PEX vs Copper
Overview Comparison Table
| Feature | PPR Pipe | PEX Pipe | Copper Pipe |
|---|---|---|---|
| Full Name | Polypropylene Random Copolymer | Cross-linked Polyethylene | Copper Alloy |
| Service Life | 50+ years | 50+ years | 70+ years |
| Max Temperature | 95°C | 93°C | 250°C+ |
| Connection Method | Hot melt (thermofusion) | Compression / crimp fittings | Soldering / brazing / press-fit |
| Corrosion Resistance | Excellent | Excellent | Good (may develop patina) |
| Bacteria Growth | Low | Low | Very low (copper is antimicrobial) |
| UV Resistance | Poor (not for outdoor) | Moderate | Excellent |
| Cost | Low (most economical) | Moderate | High (3–5x PPR) |
| Installation Difficulty | Easy (requires hot melt tool) | Moderate (requires special fittings) | Difficult (requires soldering skill) |
| Flexibility | Rigid (uses elbow fittings) | Flexible (can bend) | Rigid (uses elbow fittings) |
| Typical Applications | Residential water supply | Radiant floor heating, repipes | High-end residential, commercial |
PPR Pipe (无规共聚聚丙烯管)
Classification
- Cold Water PPR (S5/S4 series): Wall thickness 2.0–3.4mm, rated for cold water only
- Hot Water PPR (S3.2/S2.5 series): Wall thickness 2.8–4.6mm, rated for hot water up to 95°C
- Color Coding: White, green, or gray — color does NOT indicate quality; wall thickness and series number do
Key Specifications
| Nominal Diameter (DN) | Outer Diameter (mm) | Wall Thickness (Hot Water S2.5) | Typical Use |
|---|---|---|---|
| DN15 | 20mm | 3.4mm | Branch lines (faucets, toilets) |
| DN20 | 25mm | 4.2mm | Branch lines (showers) |
| DN25 | 32mm | 4.4mm | Main distribution |
| DN32 | 40mm | 5.5mm | Main inlet line |
| DN50 | 63mm | 7.1mm | Building main supply |
Installation Checklist
- [ ] Verify pipe series matches application (hot water pipe for hot water lines)
- [ ] Cut pipe perpendicular with dedicated pipe cutter — do NOT use a saw
- [ ] Clean pipe ends and fittings before hot melt
- [ ] Heat to 260°C; over-heating degrades material, under-heating causes weak joints
- [ ] Hold joint steady during cooling (minimum 30 seconds for DN20)
- [ ] Pressure test at 1.5x working pressure for 1+ hours before closing walls
- [ ] Mark pipe run locations on wall photos before plastering
PEX Pipe (交联聚乙烯管)
Types
| Type | Cross-linking Method | Key Characteristics |
|---|---|---|
| PEX-a | Peroxide (Engel) method | Most flexible, highest cross-linking (~75%), best memory/shape recovery |
| PEX-b | Silane method | Stiffer, moderate cost, most common in China |
| PEX-c | Electron beam (radiation) | Least flexible, budget option |
Best Use Cases
- Radiant floor heating loops (PEX-a preferred for flexibility)
- Repiping inside existing walls (can snake through cavities)
- Snow melting systems
- NOT recommended for exposed runs (UV degradation)
Copper Pipe (铜管)
Grades
| Grade | Wall Thickness | Common Use |
|---|---|---|
| Type M | Thinnest | Dry plumbing, residential water |
| Type L | Medium | Residential, commercial, heating |
| Type K | Thickest | Underground, industrial |
Installation Notes
- Always use lead-free solder for potable water lines
- Clean pipe ends with emery cloth before soldering
- Apply flux thinly; excess flux causes corrosion inside the pipe
- Press-fit copper systems (no soldering) are gaining popularity; require proprietary fittings and press tools
2. Wire Types: BV vs BVR vs RVV
Wire Type Comparison
| Wire Type | Full Name | Conductor Structure | Flexibility | Typical Use |
|---|---|---|---|---|
| BV | Copper Core PVC Insulated | Single solid strand | Low (stiff) | Concealed in-wall wiring, fixed installation |
| BVR | Copper Core PVC Flexible | Multiple fine strands | Medium | Distribution cabinets, bending required areas |
| RVV | Copper Core PVC Flexible Sheathed | Multiple fine strands, sheathed | High | Appliances, extension cords, exposed runs |
| BVVB | Copper Core PVC Flat | Multiple parallel BV conductors | Low | Surface-mounted flat cable runs |
| RVVP | Shielded Flexible | Fine strands + braided shield | High | Audio, control, communication lines |
Wire Gauge Selection by Circuit
| Circuit Type | Minimum Wire Size (mm²) | Wire Type | Breaker Rating |
|---|---|---|---|
| Lighting | 1.5 mm² | BV | 10A |
| General outlets (bedroom, living room) | 2.5 mm² | BV | 16A |
| Kitchen outlets | 4.0 mm² | BV | 20–25A |
| Air conditioner (1–1.5 HP) | 2.5 mm² | BV | 16A |
| Air conditioner (2–3 HP) | 4.0 mm² | BV | 25A |
| Central AC / instant water heater | 6.0 mm² | BV | 32A |
| Main entry (small apartment) | 10 mm² | BV | 40–50A |
| Main entry (large apartment) | 16 mm² | BV | 63A |
Current Carrying Capacity (Copper, PVC, 25°C ambient)
| Wire Size (mm²) | Approx. Max Current (A) | Max Load (220V, kW) |
|---|---|---|
| 1.5 | 15–18 | 3.3 |
| 2.5 | 22–25 | 5.5 |
| 4.0 | 32–38 | 8.3 |
| 6.0 | 40–48 | 10.5 |
| 10.0 | 55–65 | 14.3 |
| 16.0 | 75–85 | 18.7 |
Note: These are approximate values for single conductor in conduit. Actual capacity decreases with bundled conductors, higher ambient temperature, and longer runs. Always derate per local electrical codes.
3. Conduit Types: PVC vs Metal
Comparison Table
| Feature | PVC Conduit (PVC电工管) | Metal Conduit (JDG/KBG/SC) |
|---|---|---|
| Material | Rigid PVC | Galvanized steel (JDG, KBG) or black steel (SC) |
| Cost | Low | Moderate to high |
| Installation | Glue / solvent weld joints | Screw-type (JDG) or compression (KBG), threaded (SC) |
| Fire Resistance | Self-extinguishing (flame-retardant grade) | Excellent (non-combustible) |
| EMF Shielding | None | Good (metal provides shielding) |
| Corrosion Resistance | Excellent | Good (galvanized); SC requires additional protection |
| Bending | Requires heat bending or pre-formed elbows | Requires conduit bender (hand or hydraulic) |
| Common Use | Residential walls/ceilings | Commercial, fire-rated areas, exposed runs |
| Code Requirement | Acceptable for most residential | Required in some commercial/fire-rated constructions |
PVC Conduit Specifications
| Nominal Diameter | Outer Diameter (mm) | Common Use |
|---|---|---|
| 16mm | 16mm | Lighting circuits (1–2 wires) |
| 20mm | 20mm | Power circuits (2–3 wires) |
| 25mm | 25mm | Main runs, AC circuits |
| 32mm | 32mm | Service entry, bundle runs |
Fill Ratio Rule
- Conduit must NOT be filled beyond 40% of cross-sectional area for 3+ conductors
- For 1–2 conductors: max 31% fill
- Example: A 20mm conduit can hold approximately 3 x 2.5mm² wires with earth
Conduit Installation Checklist
- [ ] Use flame-retardant PVC conduit (marked with "阻燃" or flame rating)
- [ ] Maximum 2 bends (90°) between pull points / junction boxes
- [ ] Use large-radius bends — no kinks or crushed conduit
- [ ] Separate power and low-voltage (network/TV) conduits by at least 300mm
- [ ] Conduits in wet areas (bathroom) must be waterproof-sealed at entry points
- [ ] Label both ends of every conduit run before closing walls
- [ ] Leave pull string in every empty conduit for future use
- [ ] Metal conduit must be grounded (bonded) at both ends
4. Quick Reference: Material Selection by Scenario
| Renovation Scenario | Recommended Water Pipe | Recommended Wire | Conduit |
|---|---|---|---|
| Standard apartment renovation | PPR S2.5 (hot), S4 (cold) | BV | PVC |
| High-end / luxury | Copper Type L | BV (all) or BVR at panel | Metal (exposed), PVC (concealed) |
| Floor heating install | PEX-a for heating loops + PPR for supply | BV | PVC |
| Old building repipe | PEX (flexible, snakes through walls) | BVR (easier to pull) | PVC |
| Villa / multi-story | PPR S2.5 or copper | BV + RVVP for smart home | Mixed PVC + metal |
| Commercial space | Copper or PPR | BV | Metal (code required) |
5. Brand Recommendations
Water Pipes
| Brand | Origin | Positioning | Notes |
|---|---|---|---|
| WAVE (伟星) | China | Mid–high | Widely available, good warranty |
| Rifeng (日丰) | China | Mid | Market leader, PEX-a specialist |
| LESSO (联塑) | China | Mid | Broad product range |
| Uponor | Finland | Premium | PEX-a gold standard |
| Viega | Germany | Premium | Copper and press-fit systems |
Wire & Cable
| Brand | Origin | Notes |
|---|---|---|
| Far East Cable (远东电缆) | China | Largest domestic manufacturer |
| Panda Wire (熊猫电线) | China | Trusted for residential BV wire |
| Baosheng (宝胜) | China | Industrial and residential |
| NKT | Denmark | Premium European quality |
Conduit
| Brand | Notes |
|---|---|
| LESSO (联塑) | Full PVC conduit system |
| Zhongcai (中财) | Good value PVC |
| Generic JDG/KBG | Many manufacturers; verify galvanization quality |