Oufu Optical Fiber Cable Co,Ltd
Osoite: Shenyang, Liaoning, Kiina
Yhteyshenkilö: Manager Zhang:
Puhelin: 400-964-1314.
Matkapuhelin: 86 13904053300
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2025-09-12 85
Before you dig a trench or lift a cable, thorough planning is non-negotiable. First, confirm the cable specification: is it Steel Wire Armoured (SWA) or Aluminium Wire Armoured (AWA)? Check its voltage rating (e.g., 600/1000V) and its current-carrying capacity for the load. You must also plan the exact route. Identify obstacles like tree roots, other buried utilities, or areas with heavy vehicle traffic. A call to your local utility mapping service is a crucial step to avoid striking gas or water lines. Interestingly, a 2022 Electrical Safety Foundation study found that nearly 40% of electrical installation failures could be traced back to inadequate initial planning and site assessment.
You cannot lay armoured cable safely with just any tools. Your toolkit must include:
Cable Drum Stand: For controlled unreeling.
Trench Shovel/Mini-Excavator: For burial projects.
Proper Cable Glands: Specific to SWA or AWA and the enclosure material.
Hacksaw/Bolted Cutters: For cutting the cable to length.
Armour Stripping Tool: Highly recommended for clean, safe work.Www.adsscable.cn
Torque Screwdriver: For accurate termination.
Safety is paramount. Always assume the cable is live until you have proven it is dead with a dedicated voltage tester. Wear appropriate PPE: gloves, safety glasses, and steel-toe capped boots. Ensure your circuit is isolated and locked out before starting any work.
Follow these steps for a flawless installation:Www.adsscable.cn
Step 1: Prepare the Route.
For direct burial, dig a trench to the recommended depth (typically 450-600mm for a standard power circuit, but always consult local regulations). Remove sharp stones and debris. Many professionals lay a 75-100mm bed of fine sand to provide a soft, level base and prevent mechanical damage to the sheath.
Step 2: Unreel and Position the Cable.
Never drag the cable across the ground. Mount the drum on a lifter and pull the cable off carefully. For longer runs, use cable rollers to reduce friction and strain. Avoid twisting the cable during placement.
Step 3: Mind the Bend Radius.
This is a common failure point. Every armoured cable has a specified minimum bend radius (e.g., 12x the cable diameter). Exceeding this can damage the armour wires and internal insulation, creating a long-term weak spot. Use a bending roller if necessary for tight spaces.
Step 4: Backfill and Protect.
Once laid, cover the cable with another layer of sand. Then, lay coloured warning tape or protective tiles above it before backfilling the trench completely. This warns future excavators of the cable's presence beneath.
Step 5: Terminate and Earth correctly.
This is the most technically sensitive part. Strip the outer sheath, expose the armour wires, and secure them tightly within a compatible gland. The armour must be effectively earthed to provide a safe path for fault current. Our team once investigated a fault where an improperly earthed armour gland caused a terrifying enclosure electrification—a mistake easily avoided with the right gland and a torque screwdriver.
Factor | Above Ground (on Cable Tray/Bracket) | Underground (Direct Buried) |
---|---|---|
Protection | Armour protects from impact | Armour protects from soil pressure & rocks |
UV Exposure | Requires sunlight-resistant sheath (e.g., PVC) | Not an issue |
Corrosion | Risk in damp/chemical environments | Risk from specific soil types |
Installation Ease | Often easier, no digging required | More labour-intensive |
Aesthetic Impact | Visible, requires careful routing | Hidden, neater final appearance |
Using the Wrong Gland: An SWA gland on an AWA cable (or vice versa) will not grip correctly, compromising mechanical strength and electrical earthing. This is a critical safety defect.
Ignoring Corrosion: In corrosive environments (e.g., coastal, agricultural), standard galvanized steel armour may degrade. Specify stainless steel glands or AWA cable for better resilience.
Poor Earthing: The entire point of the armour is fault protection. Failing to create a solid, low-resistance earth connection at both ends renders this safety feature useless.
Termination is where the installation is finalized. Seal the gland properly to maintain the IP rating of the enclosure. Connect the internal conductors to the terminals with the correct torque settings. Once everything is connected, but before energizing, conduct rigorous tests. These must include insulation resistance testing between all conductors and between conductors and the earthed armour. Finally, a continuity test to verify the armour's earth path is essential. A 2023 NICEIC report noted that 25% of initial failed inspections were due to inadequate earth continuity on arLisääd systems.
☐ Cable type/size verified for current and voltage drop.
☐ Route planned and utilities marked.
☐ Correct depth trench dug and prepared with sand.
☐ Correct bending radius maintained.
☐ Cable protected with warning tape.
☐ Correct glands for cable and enclosure type used.
☐ Armour properly earthed and terminated.
☐ Insulation resistance and continuity tests passed.
☐ Circuit clearly labelled at both ends.
1. Q: What is the minimum depth to lay armoured cable?
A: For a standard 230V domestic power circuit, the UK Wiring Regulations (BS 7671) typically recommend a minimum depth of 450mm. However, this can vary based on the presence of additional protection like concrete slabs or warning tape. Always check the latest regulations.
2. Q: Can I bury armoured cable without a conduit?
A: Yes, that is a primary purpose of armoured cable. Its robust steel or aluminium wire armour provides mechanical protection, allowing it to be buried directly in the ground without a conduit, saving significant time and cost.
3. Q: How do I connect two lengths of armoured cable together?
A: You should never simply splice armoured cable underground. Use a certified, waterproof, and resin-filled joint kit designed for armoured cables. This maintains the cable's mechanical protection, electrical continuity, and moisture resistance at the joint.
4. Q: Why must I use a specific armour stripping tool?
A: While you can use a hacksaw, a dedicated tool makes a clean, square cut around the armour wires without nicking the inner bedding or insulation underneath. This prevents moisture ingress and protects the cable's integrity, making termination safer and easier.
5. Q: Does the armour need to be earthed at both ends?
A: Yes, the armour must be effectively earthed at both ends of the run to ensure a safe path for fault current. This is a fundamental safety requirement of the wiring regulations.