You are reading through a project specification or a bill of material and you find a cable called out as STA. It looks like the SWA cable that you are familiar with, but the cost is lower. Is this a misprint? Will this product crack or otherwise fail underground?
Confusion between SWA and XLPE STA Armored power cable is one of the most common issues in cable procurement. While they both provide protection, treating them as interchangeable can lead to snapped cables during installation or structural failure in vertical runs.
If you are a cost estimator looking to save budget, or an engineer verifying a spec, this guide breaks down exactly what steel tape armor is. We will explain why it is the superior “static” choice, why you should never pull it hard, and how it compares to its wire-armored cousin.
What is XLPE STA (Steel Tape Armored) Cable?
XLPE STA armored power cable is a high performance electrical cable for power transmission and distribution applications, designed for use in applications in which the cable is subjected to the risk of being crushed.
The acronym breaks down as follows:
- XLPE (Cross-Linked Polyethylene): This is the material that insulates the copper or aluminum conductor. XLPE is better than ordinary PVC due to its higher allowable operating temperature (90ºC) and higher resistance to water and chemicals.
- STA (Steel Tape Armor): This is the defining feature. Instead of a ring of round wires, this cable is wrapped in two layers of galvanized steel tape. The tapes are applied helically (in a spiral) so that the top layer covers the gap of the bottom layer, ensuring 100% coverage.
Unlike SWA, which uses round steel wires twisted around the cable,STA cable uses two layers of helical galvanized steel tape wrapped around the inner bedding. In many technical circles, you might hear this referred to as Double Steel Tape Armor (DSTA) or under the specific code YJV22 armored cable or N2XBY armoured power cable.
The Construction of YJV32 armored cable
To see what it could do, you have to peel back the layers:
- Conductor: Stranded Normally stranded, Copper (Cu) or Aluminum (Al).
- Insulation (XLPE): This compound enables the cable to be used at elevated temperature of 90°C as against PVC and thereby the current rating of the cable is increased.
- Inner Sheath/Bedding: A soft PVC layer, which buffers the hard steel tape from the fragile insulation.
- Armor (The Critical Layer): Two separate layers of galvanized steel tape. The second layer overlaps the gaps the first layer leaves behind so that you have 100% coverage.
- Outer Sheath: Normally PVC for the inner jacket and PE (Polyethylene) for the outer jacket to resist to rust and water.
STA vs. SWA: The Critical Differences
This is where the decision is made. Choosing the wrong armor type can be an expensive mistake.
Tensile Strength (Pulling Force)
This is the number one difference.
- SWA (Wire): Round wires act like a steel rope. You can attach a pulling sock to the armor and pull this cable through long ducts with significant force. The wires distribute the tension.
- STA (Tape): The tapes are wound spirally. If you pull this cable hard, the tape acts like a slinky—it stretches and effectively “unwinds” or snaps.
- The Rule: STA armored cable serves as a “laying” cable, not a “pulling” cable. It has strictly limited tensile strength.
As for more information about SWA, you can read our this article:
N2XRY / YJV32 Guide: Best XLPE SWA Armored Power Cable Specs
Crush Resistance & Vermin Proofing
While SWA is strong, it has tiny gaps between the wires. Steel tape armored cable provides 100% coverage.
- Crush: STA offers excellent radial protection. It resists heavy weight pressing down on it (like soil or concrete).
- Vermin: Rats and termites find it much harder to penetrate the overlapping steel layers of an STA cable compared to wedging teeth between wires.
Magnetic Shielding & EMI
For circuits sensitive to interference, tape armor can sometimes offer a slight advantage. The continuous overlap of the steel creates a more effective magnetic screen than the wire gaps in SWA, reducing electromagnetic interference (EMI) escaping or entering the cable.
Cost and Weight
STA armored cable is almost always cheaper and lighter than SWA. The manufacturing process uses less steel by weight to achieve the same crush protection rating. For projects with miles of cabling, switching to YJV22 0.6/1kV XLPE STA armoured power cable can save 10-20% on material costs.
| Feature | XLPE SWA (Wire Armor) | XLPE STA (Tape Armor) |
|---|---|---|
| Tensile Strength | High (Can be pulled) | Low (Do not pull) |
| Crush Resistance | Good | Excellent |
| Flexibility | Moderate | Stiff / Less Flexible |
| Vermin Protection | Good | Superior |
| Ideal Use | Vertical runs, Ducts, Pulling | Direct Burial, Trays |
| Cost | Higher | Lower (Budget Friendly) |
Technical Specifications & Standards
When ordering N2XBY armoured power cable, you need to ensure compliance with international standards. Professional engineers will look for adherence to:
- IEC 60502: The global standard for power cables with extruded insulation.
- BS 5467: While usually associated with SWA, many specifications derive their bedding and armoring thickness requirements from British Standards.
- IEC 60228: Specifies the copper or aluminum conductors.
The “Single Core” Exception
You will rarely see single-core XLPE insulated STA cable used for Alternating Current (AC). Why? A magnetic field surrounds any wire carrying current.
- If you wind a magnetic material (steel tape) around a single core carrying AC, the steel becomes the transformer core.
- That induces “Eddy Currents” in the armor making the cable to get hot and possibly melt.
- Solution: For single-core cables you have to use Aluminum Wire Armor (AWA), because aluminum isnon-magnetic. STA is exclusively multi-core cable (2-core, 3-core, 4-core etc) where the magnetic fields cancel out each other.
Applications: Where to Use STA Cable
If you are looking for cost-effective alternative to SWA, here are the “Green Light” scenarios where STA excels.
1. Direct Burial in Loose Soil
This is the sweet spot for XLPE STA armored power cable. If you are digging a trench, laying a sand bed, and placing the cable on top (without dragging it through a long pipe), STA provides the necessary armor against the weight of the backfill. It is the perfect direct burial cable for environments where the earth is stable.
2. Areas infested with rodents
Agricultural environments, farms, and food production facilities are also plagued by the problem of rats gnawing on cables. The spirally wrapped steel tape works as a metal barrier and is so rodent resistant that you could not get to the XLPE insulation if you tried.
3. Auxiliary and Control Circuits
For N2XBY control cables laid in troughs or trays where there is no mechanical tension, STA provides shielding and protection at a lower weight than SWA.
Where NOT to Use STA (The “Red Light” Zones)
Despite the cost savings, using steel tape armored cable in the wrong place is dangerous.
1. Vertical Runs and Risers
Never use STA for long vertical installation (e.g., up a mine shaft or a tall building riser). The steel tape cannot support the weight of the copper conductors inside. Over time, gravity will pull the conductors down, causing the armor to unravel or the internal insulation to stretch and tear. SWA is mandatory here because the wires act like a suspension bridge cable.
2. High-Flexibility Areas
STA Armoured Cable is thicker and more rigid than SWA. When running the cable around tight corners (tight bend radius) the steel tape could buckle or kink which could cut the inner bedding.
3. Areas with Heavy Vibration
Industrial plants with heavy shaking machinery should avoid connecting STA directly to the equipment. Constant vibration can cause the spiraled tape to fatigue or loosen over time compared to the tighter bind of steel wire.
Need a cable for high-tension pulling?
If your project requires pulling cable through long conduits or ducts, STA is likely to fail. You should consider the SWA alternative. For a detailed look at wire-armored options, read our description on YJV32 Steel Wire Armored Cable.
Purchasing Guide: What to Specify
To get the right product from suppliers, use the correct terminology. A vague request gets you vague quotes.
Copy-Paste Specification Template:
“Low Voltage (0.6/1kV) Power Cable, Copper Conductor, XLPE Insulation, PVC Bedding, Double Steel Tape Armored (DSTA/STA), PVC Outer Sheath. Flame Retardant to IEC 60332.”
Key Variations to watch for:
- N2XBY: The VDE (German) code for Copper/XLPE/Steel Tape/PVC.
- YJV22: The Chinese standard code for the same construction (very common in global markets).
- Aluminum Conductor: If you want to save even more money, ask for Aluminum STA Cable (often coded as NA2XBY or YJLV22).
Conclusion: The Smart Strategy for Armored Cable
XLPE STA Armored power cable is not just a “cheap alternative” to SWA; it is a specialized tool. It sacrifices tensile strength to offer superior crush resistance, vermin protection, and reduced material costs.
The Bottom Line:
- Choose STA if you are laying the cable into a trench, burying it directly, or laying it in a tray where it won’t move. It is the champion of underground power cable solutions for budget-conscious projects.
- Avoid STA if you have to pull the cable through 50 meters of conduit or run it vertically up a wall.
Are you lost in the selection of the best YJV22 armored cable for your project? Choosing between STA and SWA is more than just a cost comparison – it’s a consideration for the life expectancy of your infrastructure. At ANPU CABLE, We are professional manufacturer of XLPE STA Armored power cable (YJV22 or N2XBY), our products comply with the IEC international standards with high quality. Whether you’re working on a direct burial project, or you need a bulk quote for commercial distribution, our tech team can get you the specs you need. Contact us now for best price and best service.
