Why Proper Armoured Cable Connection is Non-NegotiableUnlike standard cables, connecting armoured cable involves dealing with its metallic armour. This armour provides crucial mechanical protection but must be correctly terminated to ensure:
Electrical Safety: The armour needs effective earthing (grounding) to safely conduct fault currents away, preventing it from becoming live under fault conditions. Neglecting this is a critical error.
Environmental Protection: The cable gland assembly seals the entry point, preventing dust, moisture, or vermin from entering the enclosure and damaging conductors. A poorly installed cable gland is like an open door for trouble.
Long-Term Reliability: Strain relief prevents conductors from being pulled or twisted, protecting connections inside the termination box. Our team encountered this in a 2023 warehouse project – vibration over time loosened an improperly relieved cable, causing intermittent faults that took days to trace! Therefore, doing it right from the start saves headaches later.www.adsscable.cn
Armoured Cable Termination: Key Methods Compared
Specifically, the two primary ways of armoured cable termination involve glands. Choosing the right one is step zero. Let's break down the options:
Feature | Traditional Brass Gland Potting Kit | Compression Gland with Integral Seal |
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Sealing | Requires separate compound/sealing ring | Built-in sealing ring/compound |
Earthing | Separate earth tags/banjos | Integrated earth path |
Speed | Slower (multiple components) | Faster (single unit assembly) |
Skill Level | Requires 更多 care/practice | Generally simpler to install |
Cost | Lower component cost | Higher component cost |
Best For | Very harsh environs, older practices | Most general industrial/commercial |
Step-by-Step Guide to Connecting Armoured Cable
Ready to get hands-on? Follow these 5 expert steps for secure connecting armoured cable:
Gear Up & Prep the Cable End
Cut the cable cleanly. Measure back the required outer sheath length (check gland specs!). Using a specialist armoured cable stripper or careful knife work, remove the outer PVC/LSFH sheath to expose the armour wires. Crucially, avoid nicking the inner bedding or conductor insulation. A smooth cut here prevents future tears.
Prepare the Armour & Fit the Gland Components
Cleanly trim any excess armour wire protrusions. Slide the gland nut, seal, and body onto the cable in the correct order. Push the armour wires back slightly over the bedding. For example, on a brass gland, ensure the sealing ring sits flush against the armour cut end.
Secure the Gland & Achieve Earth Continuity
Thread the gland body into the enclosure hole and tighten the gland nut firmly. This locks the armour securely. Now, establish the vital earthing path. For brass glands, fit an earth tag or "banjo" under a gland locknut and connect the earth conductor tightly. Compression glands usually earth via contact with the enclosure. Actually, use a multimeter to confirm low resistance (< 0.5 Ohms) between armour and earth terminal.
Seal the Deal (For Brass Glands) & Connect Conductors
If using a potting kit: Clean the exposed bedding area. Pack the void between conductors with the supplied compound/sealing putty. Fit the shroud and tighten. This seals against moisture ingress. Finally, terminate the phase, neutral, and earth conductors correctly onto their terminals within the enclosure, providing adequate slack.
Final Checks & Strain Relief
Double-check all terminals are tight. Confirm no conductor insulation was damaged during stripping. Crucially, ensure the cable gland itself is securely mounted to the enclosure and that the cable is adequately supported nearby (within 300mm) to prevent strain on the gland or internal connections. This final armoured cable installation step is often overlooked.
Common Armoured Cable Connection Pitfalls to Avoid
⚠️ WARNING: Critical Mistakes That Compromise Safety! ⚠️
Neglecting Armour Earthing: This is the cardinal sin. Un-earthed armour is a lethal shock risk during faults. Always verify the earth continuity path.
Damaging Bedding/Insulation: Nicking inner layers during stripping creates weak points leading to future shorts or insulation breakdown.
Incorrect Gland Selection: Using a gland not rated for the cable diameter or environmental conditions (IP rating, chemical resistance) invites failure.
Poor Sealing: Inadequate compound packing in brass glands or loose compression fittings allow moisture ingress, causing corrosion and tracking.
Ignoring Strain Relief: Letting the cable weight hang on the gland stresses connections internally and can pull wires loose over time.
Overtightening Terminals: Crushing conductor strands reduces conductivity and increases resistance/heat. Follow torque specs!www.adsscable.cn
Your Armoured Cable Connection Success Checklist
Before energizing any circuit, run through this expert checklist:
Correct gland type selected for cable & environment?www.adsscable.cn
Outer sheath cut cleanly, armour exposed without damage to inner layers?
Gland fully assembled in correct order, tightened securely to enclosure?
Armour effectively earthed? Continuity verified (<0.5 Ohms to earth point)?
Brass gland fully sealed with compound/shroud? Compression gland seal intact?
Conductors terminated correctly on terminals? Terminals tight but not crushed?
Cable adequately supported near gland (within 300mm) for strain relief?
Inner conductor insulation visually undamaged?
Overall IP rating of enclosure/gland maintained?
Connecting with Confidence
Connecting armoured cable demands attention to detail and respect for safety protocols. By understanding the why behind each step, selecting the right armoured cable termination method, and rigorously avoiding common errors, you ensure installations are safe, durable, and compliant. However, remember that complex scenarios or hazardous locations might require certified professionals. Ultimately, mastering these expert tips empowers you to tackle armoured cable installation with greater confidence and competence, knowing you've built in safety from the ground up.
FAQs: Connecting Armoured Cable
Q: Can I just cut off the armour wires when connecting armoured cable?
A: Absolutely not! The armour must be properly terminated via the gland and earthed. Cutting it off negates its mechanical protection and creates a major safety hazard by removing the essential earth path.
Q: Do I always need a potting kit with brass glands?
A: Generally, yes, for outdoor or damp locations. The compound provides the vital environmental seal. For dry, indoor locations, some brass glands use rubber sealing rings instead, but always check the gland manufacturer's specifications for its sealing requirements.
Q: Is it okay to use standard cable glands on armoured cable?
A: No. Standard glands lack the mechanism to grip and earth the steel armour. You must use glands specifically designed and rated for armoured cable termination (brass or compression type).
Q: How tight should I tighten the cable gland nut?
A: Tighten firmly by hand using appropriate spanners, but avoid excessive force. Overtightening can distort the gland body or crush the cable components, compromising the seal and earth connection. Firm and secure is the goal; consult manufacturer specs if available.
Q: Why is strain relief so important near the gland?
A: Without proper support, the weight of the cable or accidental tugs will pull directly on the conductors and terminals inside the enclosure. This stress can loosen connections over time, increase resistance (causing heat), and potentially lead to arcing or failure. Therefore, always secure the cable within 300mm of the gland.