1. The Three Termination Methods Compared (Crimp / Twist / Solder)
| Method | Principle | Reliability | Application | Code |
|---|---|---|---|---|
| Crimp | Wire cap / cold-pressed terminal, mechanically compressed | ★★★★★ | All permanent terminations | GB/T 9330 |
| Twist | Hand twist + insulating tape | ★★★ | Temporary / repair | Not recommended for permanent |
| Welding | Solder | ★★★★ | Signal / low-voltage | Requires auxiliary support |
2. Crimp Terminations in Detail (Recommended Practice)
Crimping is theonly permanent connection method recommended by GB 50303. Key operating points:
- Stripping: remove 8–12mm of insulation without nicking the conductor.
- Crimp-on ferrule: select the ferrule that matches the conductor cross-section (e.g., OT2.5 for 2.5 mm²).
- Crimping: use a dedicated crimping tool and make two crimps. The joint must not pull apart after crimping.
- Insulation: cover with heat-shrink tubing or an insulating cap. Exposed conductor ≤ 1 mm.
3. Twist splicing: when is it allowed? (Temporary / repair)
Twist splicing is only permittedtemporary repair or emergencyuse. It must not be used for permanent installation. Twist splicing requirements: (1) cross the two conductors at 90° and twist ≥ 6 turns; (2) bend back the ends ≥ 2 turns; (3) after twisting, wrap with insulating tape first, then with waterproof tape.Twist splices will not pass formal project acceptance..
4. Soldering: low-voltage signal circuits only (signal / instrumentation)
Soldering is used forsignal lines, instrument lines and other low-voltage signal circuits. Soldering key points: (1) the solder joint must be bright with no cold solder; (2) heat-shrink tubing must be applied after soldering for insulation; (3) large-cross-section power conductors must not be soldered (solder has high resistance and will overheat under high current).
5. Crimping tool selection (by cross-section)
| Conductor cross-section | Crimp-on ferrule | Crimping tool | Crimping die |
|---|---|---|---|
| 0.5–1.5mm² | OT0.5–1.5 | Manual | 0.5–1.5 |
| 1.5–2.5mm² | OT1.5–2.5 | Manual | 1.5–2.5 |
| 4–6mm² | OT4–6 | Hydraulic | 4–6 |
| 10–16mm² | OT10–16 | Hydraulic | 10–16 |
FAQ FAQ
Must junction box wiring always be crimped?
GB 50303 recommends crimping. Twist splicing is only for temporary repair; formal project acceptance requires crimped or bolted connections.
What is the pull-out force after crimping?
For 2.5 mm² copper wire, the pull-out force after crimping is ≥ 80 N. Passing means it does not pull apart.
How do you connect copper and aluminum conductors?
You must usea copper-to-aluminum transition terminal. Direct copper-to-aluminum contact causes electrochemical corrosion, and the increased contact resistance leads to overheating.
Can solder be used on power conductors?
No. Power conductors carry high current; solder has high resistance and will melt from heat, causing poor contact or even fire.
Related pages:Technical notes · Products · Industries · Resource center · FAQ · Get a quote