NG-A BTLY 4x35+1x16mm2 Mineral Insulated Fire Resistant Aluminum Sheath Cable for Emergency

Cable Designation & Meaning

Construction: Copper conductors, XLPO (cross-linked polyolefin) or mineral ceramic insulation, continuous corrugated aluminium sheath, LSZH outer sheath, flexible design.

NG-A(BTLY) 4×35+1×16 mm² (flexible mica-tape mineral-insulated Al-sheathed fire-resistant cable) — Specification & Engineering Data 

1. Overview & Ratings. NG-A(BTLY) 4×35+1×16 — flexible mineral-insulated fire-resistant cable with corrugated aluminum tube sheath, four 35 mm² copper power cores (L1/L2/L3/N) plus one 16 mm² PE core, wrapped in synthetic phlogopite mica tape and enclosed in a continuous corrugated aluminum tube, rated 0.6/1 kV; built and tested per GB/T 19216 / GB/T 13033. The cable maintains circuit integrity at 750 °C for 90 minutes. Ø ≈ 36.5 mm, ≈ 2450 kg/km, wooden drums.

2. Construction Stack (Conductor → Outer).

3. Electrical Characteristics. R ≤ 0.524 Ω/km (35 mm²) / ≤ 1.15 Ω/km (16 mm²) at 20 °C; routine test 3.5 kV AC / 5 min; insulation resistance ≥ 100 MΩ·km. Reference ampacity ≈ 130 A (4×35 loaded, free air, 30 °C).

Insulation & Sheath Data

Electrical Parameters

Reference values: 35 mm² Cu at 140 A, 3-phase 400 V → max balanced load ≈ 97 kVA. Voltage drop at 140 A ≈ 93.4 V/km per core (≈3.8% per 100 m at 400 V).

4. Thermal & Fire. 90 °C continuous conductor temperature; short-circuit 250 °C; fire rating 750 °C / 90 min per GB/T 19216 — the cable remains energised during fire with impact and water spray. Mica tape is non-combustible; PVC outer sheath contains halogen (LSZH outer available for halogen-free).

Temperature Characteristics

Fire Performance (NG-A / BTLY — Mineral Insulated, Fire Resistant)

BS 6387 Classification:

5. Installation Practice & Handling. Install fire cable end seals at both ends. Bend ≥ 12 × OD ≈ 440 mm fixed. Use Cu compression lugs + end sealing kits. The Al tube is the primary fire barrier; the thin PVC outer sheath is for corrosion protection. Lighter than Cu-sheathed BTTRZ — easier to handle.

Mechanical & Installation Parameters

6. Typical Service Applications. Fire pump power supply, emergency lighting circuits, smoke control systems, fire alarm circuits, evacuation signalling, critical life-safety power — any circuit that must remain operational during a fire.

7. Testing & QA Regime. Routine: conductor DC resistance, 3.5 kV AC withstand, insulation resistance ≥ 100 MΩ·km. Type: GB/T 19216 fire test (750 °C / 90 min with impact and water spray), crush resistance, halogen test, end seal integrity.

Cable Parameters

Cable Test Parameters

Cable Cross Section Structure

Construction Description

8. Standards & Conformity. GB/T 19216 (fire resistance test); GB/T 13033 (mineral-insulated cables); GB/T 3956 (conductors). Rated 0.6/1 kV fire-rated power circuit.

9. Packaging, Storage & Logistics. 100 m per wooden drum with sealed ends. Continuous marking: NG-A(BTLY), 4×35+1×16, 0.6/1 kV, 750 °C, GB/T 19216, metre marks. Store dry, indoor, with factory end seals intact.

10. Procurement Specification. State "NG-A(BTLY) 4×35+1×16, 0.6/1 kV, 750 °C/90 min" + length. Order matching end sealing kits. Confirm against factory fire test certificate. Do not substitute ordinary YJV for fire-rated circuits.

11. Cable Industry FAQ.

• Q1: What makes NG-A(BTLY) fire-resistant? Unlike RVV (PVC insulation which burns at 70 °C), NG-A(BTLY) uses synthetic mica tape (phlogopite) wrapped around each conductor, and a corrugated aluminum tube as the sheath. Neither mica tape nor aluminum burns. The cable maintains circuit integrity at 750 °C for 90 minutes.
• Q2: What is the difference between BTTRZ and NG-A(BTLY)? BTTRZ uses a copper tube + MgO powder insulation (950 °C/180 min, 105 °C, 3850 kg/km). NG-A(BTLY) uses an aluminum tube + mica tape insulation (750 °C/90 min, 90 °C, 2450 kg/km). BTTRZ has higher fire rating and higher temp, but is heavier and more expensive. BTLY is lighter, easier to install, and sufficient for most fire-rated circuits.
• Q3: Why is the aluminum tube used instead of copper? Aluminum is ~1/3 the density of copper, making the cable much lighter (2450 vs 3850 kg/km). This reduces installation labor and support structure load. Aluminum also does not burn and provides a water-tight seal.
• Q4: What is mica tape? Mica tape is a thin sheet of phlogopite mineral paper backed with glass cloth. It is non-combustible, heat-resistant to 750 °C, and flexible. It is wrapped around each conductor to provide fire-resistant insulation without the MgO powder fill of rigid mineral cables.
• Q5: Can NG-A(BTLY be used outdoors? Yes — the PVC outer sheath protects the Al tube from corrosion. For direct burial, the Al tube is water-tight. No additional armor needed.
• Q6: What is the fire rating difference between 750 °C and 950 °C? 750 °C/90 min (GB/T 19216) is the standard fire rating for most building emergency circuits. 950 °C/180 min (BS 6387 class C) is a higher rating for critical industrial fire pumps. BTTRZ meets 950 °C; NG-A(BTLY) meets 750 °C.
• Q7: Does NG-A(BTLY) need armor? No — the corrugated aluminum tube itself provides crush and impact resistance. This is why it is the standard for fire-rated circuits.
• Q8: Can RVV be used for fire pump circuits? No — RVV's PVC insulation burns at ~250 °C and releases toxic smoke. Fire pump circuits MUST use mineral-insulated cable (BTTRZ/BTLY) or fire-rated silicone cable.
• Q9: What is the difference between BTLY and BTTW? BTLY uses an aluminum tube sheath. BTTW uses a copper tube sheath (similar to BTTRZ). BTLY is lighter and cheaper; BTTW has higher fire rating.
• Q10: How do I terminate NG-A(BTLY)? Cut the cable square, remove the outer PVC, slide on the end seal gland, install the Cu lug, and crimp. The seal must be moisture-tight. Improper termination is the #1 failure point.
• Q11: Is NG-A(BTLY) halogen-free? The PVC outer sheath contains halogen. For halogen-free applications, specify the LSZH outer sheath version (BTLY with LSZH). The mica tape itself is halogen-free.