5.3 Teck90 Armoured Cable & Industrial Cable Tray Systems

5.3 Teck90 Armoured Cable & Industrial Cable Tray Systems

In Canadian heavy industry—including mining operations, pulp and paper mills, petrochemical refineries, smelters, and chemical processing plants—cabled distribution systems utilizing Teck90 armoured cable and engineered cable tray networks are the dominant infrastructure choice. Compared to rigid conduit, cable tray systems offer superior flexibility, simplified capacity expansion, rapid installation, and excellent heat dissipation. However, maintaining safety and code compliance requires strict adherence to CEC Section 12 rules governing cable bending, termination, support spacing, tray fill, and equipment bonding.

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1. Teck90 Cable Anatomy & Engineering Standards (CSA C22.2 No. 131)

Originally developed in the Canadian mining sector to endure severe physical punishment, subterranean moisture, and acidic rock drainage, Teck90 cable is manufactured to CSA Standard C22.2 No. 131. It is certified for use in wet and dry locations, direct earth burial, outdoor cable trays exposed to sunlight, and Class I, Zone 1 and Zone 2 hazardous locations.

   [Cross-Section of Multi-Conductor Teck90 Cable]
   ┌────────────────────────────────────────────────────────┐  ◄── 1. Outer PVC Jacket (-40°C, FT4, UV/Oil)
   │ ┌────────────────────────────────────────────────────┐ │  ◄── 2. Interlocking Armour (Al or Galv Steel)
   │ │ ┌────────────────────────────────────────────────┐ │ │  ◄── 3. Inner Bedding PVC Jacket
   │ │ │   ┌───┐            ┌───┐                       │ │ │
   │ │ │   │Cu │ (Phase A)  │Cu │ (Phase B)             │ │ │  ◄── 4. XLPE / RW90 Insulation (90°C Wet/Dry)
   │ │ │   └───┘            └───┘                       │ │ │
   │ │ │           ┌───┐            ┌───┐               │ │ │
   │ │ │           │Cu │ (Phase C)  │GND│ (Bare Bond)   │ │ │  ◄── 5. Compact Stranded Copper Conductor
   │ │ │           └───┘            └───┘               │ │ │
   │ │ └────────────────────────────────────────────────┘ │ │
   │ └────────────────────────────────────────────────────┘ │
   └────────────────────────────────────────────────────────┘

The Six Structural Layers

1. Phase Conductors: Concentric or compact stranded Class B annealed copper (or ACM 8000 series aluminum). Available in multi-conductor power configurations (3-conductor with ground, 4-conductor with ground) and multi-pair/triad instrumentation cables.
2. Conductor Dielectric Insulation: Chemically cross-linked polyethylene (XLPE), classified as RW90. Rated 90°C continuous in both wet and dry environments. It provides high dielectric breakdown strength and high thermal short-circuit withstand capabilities.
3. Equipment Bonding Conductor: One or more bare annealed copper bonding conductors installed in intimate contact with the cable interior, sized in accordance with CEC Rule 10-614 and Table 16.
4. Inner Bedding Jacket: Extruded flame-retardant polyvinyl chloride (PVC). Functions as an environmental moisture barrier and provides a smooth, uniform mechanical cushion preventing the metal armour from biting into the conductor insulation.
5. Interlocking Armour: Continuously rolled, flexible interlocking metallic tape—most commonly aluminum (lightweight, highly corrosion resistant) or galvanized steel (superior crush resistance in heavy mining). The armour provides extreme mechanical impact protection, rodent resistance, and an auxiliary electrical bonding path.
6. Outer Protective Jacket: Low-temperature, sunlight-resistant, flame-retardant PVC (certified FT4 flame test). Rated for cold impact and installation down to -40°C (-40°F), with high resistance to acids, alkalis, hydrocarbons, and ozone.

Voltage Classifications

• 600 V Standard: Utilized for standard industrial branch circuits, low-voltage MCC feeds, and lighting distribution.
• 1000 V Heavy Industrial: Required on 600 V ungrounded systems, High-Resistance Grounded (HRG) systems, and pulse-width-modulated (PWM) VFD motor output circuits where reflected wave transients (dI/dt and dV/dt) exceed 600 V peak.
• Medium-Voltage Teck (5 kV to 15 kV): Features semi-conducting strand screens, cross-linked insulation, semi-conducting insulation screens, and helically wrapped copper shielding tape beneath the inner jacket.

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2. Mechanical Installation Guidelines: Bending Radius & Support Spacing

Improper handling during cable pulling or sharp bending breaks the interlocking armour joints, crushes inner conductors, or buckles delicate tape shielding.

Minimum Bending Radius (CEC Rule 12-614)

   Minimum Bending Radius (R) Measured to Inner Curve:
   
   Teck90, finished static bend (CEC 12-614):   Same cable while under pulling tension:
          ┌───────┐                               ┌───────────┐
         /         \                             /             \
        │     R     │                           │       R       │
        │◄─────────►│                           │◄─────────────►│
         \         /                             \             /
          └───────┘                               └───────────┘
         R ≥ 6 × OD                              R ≥ 12 × OD

• Interlocked / continuously welded armoured cable (standard 600 V or 1000 V Teck90), static installed bend: under CEC Rule 12-614 the radius of the inner edge of the bend shall be not less than 6 times the overall outside diameter (6 × OD) of the cable.
• The same cable while it is under pulling tension (being pulled into a raceway or duct, or re-spooled): the radius must be not less than 12 × OD. Bending a cable tighter than this while it is loaded in tension is what separates and buckles interlocked armour.
• Shielded medium-voltage cable (>1 kV): follow the cable manufacturer's published limit and the governing ICEA/AEIC installation standard, which for tape-shielded and wire-shielded constructions is commonly 12 × OD or greater. Shielded cables require a larger radius to prevent crushing or separating the thin copper electrostatic shield tape, which would otherwise concentrate electrical stress and cause dielectric puncture.

Calculation Example: A 3-conductor 500 kcmil 1000 V copper Teck90 cable has an overall outside diameter of 60 mm (2.36 inches). The static code minimum under Rule 12-614 is 6 × 60 mm = 360 mm (14.2 inches), while the radius that must be respected in the sheave and at every direction change during the pull is 12 × 60 mm = 720 mm (28.3 inches). Rigging the pull to the 360 mm figure is the classic field mistake — the code number applies to the finished, unloaded bend.

Support Spacing (CEC Rule 12-618)

• Horizontal & Vertical Runs: Teck90 cable must be securely supported by approved straps, cable cleats, or tray rungs at intervals not exceeding 1.5 metres (5 feet).
• Distance from Terminations: Cables must be securely supported within 300 mm (12 inches) of any electrical enclosure, junction box, conduit fitting, or cable tray exit point.
• Vertical Drops: On vertical risers in open shafts or industrial towers, cables must be secured with certified heavy-duty cable cleats spaced to support the deadweight tension without placing mechanical shear load on the termination glands.

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3. Industrial Terminations: Watertight vs. Explosion-Proof (TMCX) Connectors

Terminating Teck90 cable requires mechanical securing, environmental sealing, and low-impedance electrical bonding of the interlocking metal armour.

   [EXPLOSION-PROOF TMCX BARRIER GLAND]
   Outer Jacket     Armour Grip Ring     Compound Chamber       Hub Thread & Bonding
   Elastomer Seal   (360° Ground Stop)   (Epoxy Putty Barrier)   Bushing to Enclosure
   ┌───────────────┬────────────────────┬──────────────────────┬─────────────┐
   │▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒│  [========]        │▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓│             │==► Inside
   │  Outer PVC    │  Armour Clamped    │Potting Resin Seals   │Ground Lug & │    Enclosure
   │  Sealed       │  for Bonding       │Individual Conductors │Locknut Bite │
   └───────────────┴────────────────────┴──────────────────────┴─────────────┘

Standard Industrial Watertight Teck Connectors

Used in non-hazardous industrial environments (NEMA 4, 4X wet, outdoor, washdown locations):

1. Outer Jacket Seal: An elastomeric neoprene or rubber compression grommet compresses tightly around the outer PVC jacket, preventing moisture, dust, and corrosive water ingress.
2. Armour Ground Stop & Grip Ring: An internal split brass or aluminum ring clamps with 360-degree circumferential contact around the bare interlocking metal armour. This provides high mechanical pullout resistance and ensures a certified fault-current return path.
3. Enclosure Attachment: Features tapered male NPT threads screwed into a threaded hub or secured through a clearance knockout with a serrated grounding locknut and an insulated bonding bushing.

Explosion-Proof TMCX Barrier Glands (Class I, Zone 1 & Zone 2 / Div 1 & Div 2)

In oil refineries, chemical plants, grain elevators, and compressor stations, electrical enclosures are classified as explosion-proof (Flameproof "d" / Explosion-Proof). If an internal spark ignites explosive gases inside the enclosure, hot flames and high-pressure gases could travel through the internal interstitial spaces of a standard cable into unclassified areas.

To prevent this, CEC Section 18 mandates certified barrier connectors (such as TMCX or TMC fittings):

• Potting Barrier Chamber: The outer jacket, armour, and inner jacket are stripped back to expose the insulated phase conductors and ground. The conductors are separated using a central silicone positioning spacer.
• Epoxy Compound Injection: A certified two-part rapid-curing liquid epoxy resin or dense malleable sealing putty is packed void-free into the gland chamber around each individual conductor core and the inner jacket.
• Explosion Containment: Upon curing, the rock-hard barrier blocks all gas, vapor, and flame migration through the cable core, maintaining the explosion-proof integrity of the enclosure.

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4. Industrial Cable Tray Systems (CEC Rule 12-2200 Series)

Cable trays provide structural support for high-density cable networks. CEC Section 12 establishes installation standards across three primary tray architectures:

Cable Tray Classifications

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5. Cable Tray Fill Rules & Conductor Ampacities

Conductor ampacity in cable trays depends on whether cables are arranged in a single layer with open spacing (facilitating natural convective cooling) or bundled together.

   SINGLE LAYER WITH MAINTAINED SPACING (Rule 12-2210(1) / Table 5D):   TOUCHING / MULTI-LAYER:
   ┌────────────────────────────────────────────────────────┐           ┌────────────────────────────────┐
   │  [Cable 1]     ◄─ d ─►     [Cable 2]     ◄─ d ─►       │           │  [Cable 1][Cable 2][Cable 3]   │
   │  (Diam = d)                (Diam = d)                  │           │  (Heat Trapped Between Cables) │
   └────────────────────────────────────────────────────────┘           └────────────────────────────────┘
   Free Air Ampacity (Table 1 / Table 3 / Table 5D)                     Raceway Ampacity (Table 2 / Table 4)
   NO Bundling Derating (Factor = 1.0)                                  WITH Table 5C Derating Applied!

Multi-Conductor Cables in Ladder Tray (CEC Rule 12-2202 & Rule 12-2210)

1. Single Layer with Maintained Spacing (Rule 12-2210(1)): Where multi-conductor cables (such as 3-conductor Teck90) are installed in a single layer in open ladder tray, and a clear spacing of not less than one cable diameter is maintained between adjacent cables:
   • Conductor ampacity is determined using the free air ratings of Table 1 (copper) or Table 3 (aluminum), modified by Table 5D.
   • Mutual heating between cables is negligible; Table 5C derating factors do not apply.
2. Cables Installed Without Maintained Spacing (Touching): Where multi-conductor cables are laid touching in a single layer or randomly bunched in the tray:
   • Conductor ampacity must be taken from Table 2 (copper in raceway/cable) or Table 4 (aluminum in raceway/cable).
   • Furthermore, if more than three current-carrying conductors are present in the grouping, Table 5C derating factors must be applied.
3. Tray Depth & Projection (Rule 12-2202(1)): Cables installed in cable tray must not project above the top edges of the tray side rails. Cables must be arranged neatly and secured with approved clamps or heavy-duty nylon-coated stainless steel banding.

Single-Conductor Cables in Cable Tray (CEC Rule 12-2202(2) & Rule 4-004)

Single-conductor cables (e.g., 500 kcmil or 750 kcmil single-conductor copper Teck90 or RW90) introduce severe inductive reactance and circulating eddy currents:

• Size Restriction: Single conductors installed in cable tray must be No. 1/0 AWG or larger.
• Trefoil (Triangular) Configuration: Three-phase single conductors must be bundled in triangular (trefoil) groups (Phase A, B, and C strapped together every 1.0 m) or flat grouped closely together. This ensures mutual magnetic field cancellation, balancing phase reactances and preventing inductive heating in the steel tray side rails.

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6. Cable Tray Bonding, Expansion Joints & Structural Continuity (CEC Rule 12-2208)

Under CEC Section 10 and Section 12, metal cable tray networks are classified as equipment bonding conductors. In the event of an insulation failure or phase-to-tray fault, the tray must conduct ground-fault current back to the source to trip the upstream circuit breaker instantaneously.

   [Tray Section 1]                                 [Tray Section 2]
   ═══════════════════════╗                 ╔═══════════════════════
                          ║   EXPANSION GAP ║
                          ╚═════╗     ╔═════╝
                                ║     ║
                        ┌───────╨─────╨───────┐
                        │ Sliding Splice Plate│ (Structural sliding only;
                        └───────┬─────┬───────┘  NOT certified for bonding)
                                │     │
                                ▼     ▼
                  ┌─────────────────────────────────┐
                  │ Flexible Braided Copper Jumper  │  ◄── MANDATORY BONDING JUMPER
                  │ Sized per Table 16              │      (CEC Rule 12-2208)
                  └─────────────────────────────────┘

Bonding Requirements Across Structural Expansion Joints

Industrial cable trays frequently traverse structural building expansion joints or require expansion splice plates on long outdoor runs to absorb thermal expansion:

• Sliding Splice Plates Are Insufficient: Mechanical expansion splice plates utilize loose sliding bolts and nylon washers to allow longitudinal movement. These sliding surfaces oxidize, corrode, and collect debris, creating a high electrical resistance that will arc or burn open under ground-fault currents.
• Mandatory Bonding Jumpers: CEC Rule 12-2208 mandates that all expansion joints, hinged vertical/horizontal fittings, and mechanical discontinuities must be bridged with an approved flexible copper bonding jumper.
• Sizing the Bonding Jumper (Table 16): The bonding jumper must be sized in accordance with CEC Table 16, based on the ampere rating of the largest overcurrent protective device protecting the conductors installed within that cable tray system.

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7. Inspecting and Maintaining Industrial Cables, Glands and Tray (RSOS C-16.02 / C-16.06)

Installing the cable is half of the Red Seal sub-task; the standard also requires the industrial electrician to maintain conductors, cables, raceways, boxes and enclosures. In a plant, that work is scheduled, not reactive.

Visual and mechanical inspection

Electrical testing

• Infrared thermography on terminations under load. A cable termination that runs hot relative to its two neighbours on the same feeder has a high-resistance joint, and the comparison between phases is what makes the finding reliable.
• Insulation resistance (megohmmeter) testing on de-energized, isolated and discharged cable. Compare against the installation baseline and against the other phases rather than against a single pass/fail number; a trend is the diagnostic.
• Medium-voltage cable testing does not use DC hipot on service-aged solid dielectric cable. Very low frequency (VLF) withstand testing, partial discharge measurement and tan-delta testing are the modern methods, for the reasons set out in the high-voltage section of this guide.
• Retorque terminations to the equipment's marked value on the schedule the equipment manufacturer specifies, after the connection has been through thermal cycling.

Failure patterns worth recognizing

• Water in the gland. A Teck gland fitted with the wrong sealing ring for the cable's outer diameter lets water wick down the interstices of the cable and into the enclosure, sometimes metres away and years later. The symptom is moisture inside a sealed enclosure with no visible entry point.
• Jacket chemical attack. PVC jackets in a solvent or oil area soften and swell; the correct answer is a jacket compound rated for the chemistry, not more tape.
• Single-conductor cables in steel. Single conductors of a three-phase circuit passing individually through separate steel plate openings or separate steel clamps induce heavy circulating currents and heat the steel. All conductors of a circuit pass through the same opening, and non-magnetic clamps are used where the code requires it.