NSGAFÖU and NSGAFCMÖU 1.8/3 kV Short-Circuit-Proof Single-Core Rubber Cables: DIN VDE 0250-602 Ampacity & Busbar Sizing.

By TEBAOFLEX Jyen, Senior Cable Application Specialist at TEBAOFLEX. Reviewed by the TEBAOFLEX Engineering Review Board. Fact-checked on October 19, 2026.

TL;DR: Wiring the unprotected zone between main transformer terminals, copper busbars, and incoming circuit breakers in 400 V, 690 V, or 1,000 V AC (1,500 V DC) switchgear requires cables certified as inherently short-circuit-proof and earth-fault-proof (kurzschluss- und erdschlussfest) under DIN VDE 0100-520. TEBAOFLEX NSGAFÖU 1.8/3 kV Single-Core Rubber Cable (DIN VDE 0250-602) satisfies this rule with a 1.8/3 kV dual-layer elastomer wall (90 °C 3GI3 EPR insulation + oil-resistant 5GM2 polychloroprene sheath) tested at 6.0 kV AC (TEBAOFLEX Lab, 2026). At 45 °C internal cabinet ambient, NSGAFÖU delivers +41% to +45% higher ampacity than 70 °C H07V-K PVC wire. For IGBT / SiC inverter drives and rail traction converters, NSGAFCMÖU Screened 1.8/3 kV Single-Core Wire adds an >= 85% tinned copper braid screen (transfer impedance under 15 mOhm/m, TEBAOFLEX Lab, 2026).

Case at a Glance: DIN VDE 0250-602 NSGAFÖU vs. NSGAFCMÖU vs. H07V-K Specification Matrix.

This engineering guide explains the DIN VDE 0100-520 short-circuit-proof installation rule, compares unscreened NSGAFÖU and braided NSGAFCMÖU, and provides complete 45 °C cabinet ampacity and 250 °C adiabatic short-circuit sizing tables across our Rubber Cable Portfolio.

Engineering Parameter.

Primary Product Page.

• NSGAFÖU (1.8/3 kV Unscreened).: NSGAFÖU 1.8/3 kV Rubber Cable.
• NSGAFCMÖU (1.8/3 kV & 3.6/6 kV Screened).: NSGAFCMÖU Screened Single-Core Wire.
• Standard H07V-K (450/750 V PVC Wire).: Standard EN 50525-2-31 panel wire (Reference).

Governing Standard.

• NSGAFÖU (1.8/3 kV Unscreened).: DIN VDE 0250-602 (VDE 0100-520).
• NSGAFCMÖU (1.8/3 kV & 3.6/6 kV Screened).: DIN VDE 0250-602 (Screened EMC Variant).
• Standard H07V-K (450/750 V PVC Wire).: EN 50525-2-31 (Not short-circuit-proof).

Nominal Voltage (U₀/U).

• NSGAFÖU (1.8/3 kV Unscreened).: 1.8/3 kV AC (max 2.1/3.6 kV AC, 2.7/5.4 kV DC).
• NSGAFCMÖU (1.8/3 kV & 3.6/6 kV Screened).: 1.8/3 kV AC and 3.6/6 kV AC options.
• Standard H07V-K (450/750 V PVC Wire).: 450/750 V AC (Single thermoplastic layer).

Conductor Stranding.

• NSGAFÖU (1.8/3 kV Unscreened).: Class 5 tinned copper (IEC 60228).
• NSGAFCMÖU (1.8/3 kV & 3.6/6 kV Screened).: Class 5 tinned copper (IEC 60228).
• Standard H07V-K (450/750 V PVC Wire).: Class 5 bare copper (tarnishes at high temp).

Dielectric & Sheath.

• NSGAFÖU (1.8/3 kV Unscreened).: Dual layer: 3GI3 EPR (90 °C) + 5GM2 PCP.
• NSGAFCMÖU (1.8/3 kV & 3.6/6 kV Screened).: 3GI3 EPR + >= 85% tinned Cu braid + 5GM2 PCP.
• Standard H07V-K (450/750 V PVC Wire).: Single layer: TI1 PVC (70 °C softening limit).

Max Short-Circuit Temp.

• NSGAFÖU (1.8/3 kV Unscreened).: 250 °C (5 s thermoset crosslinked wall).
• NSGAFCMÖU (1.8/3 kV & 3.6/6 kV Screened).: 250 °C (5 s thermoset crosslinked wall).
• Standard H07V-K (450/750 V PVC Wire).: 160 °C (Thermoplastic melt & flow risk).

Routine AC Test Voltage.

• NSGAFÖU (1.8/3 kV Unscreened).: 6.0 kV AC (5 min water tank FAT, 2026).
• NSGAFCMÖU (1.8/3 kV & 3.6/6 kV Screened).: 6.0 kV AC (1.8/3 kV) / 11.0 kV AC (3.6/6 kV).
• Standard H07V-K (450/750 V PVC Wire).: 2.5 kV AC (Spark test only).

Why Standard 450/750V PVC Wires Are Prohibited on Unfused Busbar Drops.

Inside a low-voltage main distribution board (LV-MDB), wind turbine converter cabinet, or diesel-electric locomotive traction bay, flexible single-core cables must tap directly onto the main copper busbars (400 V, 690 V, or 1,000 V AC, and up to 1,500 V DC in battery/solar inverters) to feed auxiliary transformers, surge arresters, voltage-sensing fuses, and active harmonic filters.

Because these tap conductors sit upstream of the branch fuse or circuit breaker, any insulation fault to the grounded steel cabinet frame creates an un-cleared bolted earth fault fed by the full 50 kA to 100 kA prospective short-circuit current of the main transformer. If wired with single-insulated 450/750 V H07V-K PVC wire, the thermoplastic wall softens at 70 °C, flows away under clamping pressure at sharp sheet-metal bends, and triggers a catastrophic arc flash.

To prevent cabinet arc flashes, DIN VDE 0100-520 (Section 521.11) and IEC 61439-1 (Section 8.6.4) require conductors in un-fused switchgear zones up to 1,000 V AC / 1,500 V DC to be inherently short-circuit-proof and earth-fault-proof. Specifying NSGAFÖU 1.8/3 kV Rubber Cable achieves this compliance without external plastic conduits:

1. 1.8/3 kV Over-Insulated Dielectric Margin: Operating a 1,800 V phase-to-earth / 3,000 V phase-to-phase rated cable on a 400 V or 690 V busbar provides a 4.3x dielectric safety factor, verified by a 6.0 kV AC factory water-tank withstand test.
2. Thermoset Crosslinked 3GI3 + 5GM2 Dual Wall: Even if a downstream overload drives the copper core to 250 °C, the crosslinked 3GI3 EPR insulation and 5GM2 polychloroprene sheath cannot melt or drip (hot-set elongation max. 58.4% at 200 °C under 20 N/cm2 load per IEC 60811-507, TEBAOFLEX Lab, 2026).

[UNIQUE INSIGHT] In our thermal-cabinet benchmark at 45 °C ambient temperature (the standard internal design ambient inside enclosed IP54 switchgear panels), replacing 70 °C H07V-K PVC cables with 90 °C NSGAFÖU 1.8/3 kV Cable increases allowable continuous current by +41.2% to +45.8% across all cross-sections (e.g., 297 A vs 207 A on 1x95 mm2, DIN VDE 0298-4, TEBAOFLEX Lab, 2026). This lets panel builders drop one full copper gauge size (e.g., using 1x95 mm2 NSGAFÖU instead of 1x150 mm2 H07V-K for a 280 A feeder), cutting bending radius and copper weight by 36%.

Core Engineering Definitions for Short-Circuit-Proof Rubber Wires.

To ensure unambiguous specification in switchgear, locomotive, and inverter bills of materials (BOM), we define four essential technical terms below:

• NSGAFÖU 1.8/3 kV cable is a flexible single-core rubber-insulated, polychloroprene-sheathed cable built to DIN VDE 0250-602 (U0/U = 1.8/3 kV). Its dual-layer thermoset wall (3GI3 EPR + 5GM2 PCP) qualifies it as inherently short-circuit-proof and earth-fault-proof in installations up to 1,000 V AC and 1,500 V DC per DIN VDE 0100-520.
• NSGAFCMÖU screened single-core wire is the electromagnetically shielded derivative of NSGAFÖU (available in 1.8/3 kV and 3.6/6 kV ratings). It incorporates a concentric >= 85% optical-coverage tinned copper wire braid screen (CM) between the 3GI3 core insulation and the 5GM2 outer sheath to suppress PWM inverter common-mode noise and protect against touch voltage.
• Inherently short-circuit-proof routing (kurzschluss- und erdschlussfeste Verlegung) is an electrical installation method under DIN VDE 0100-520 and IEC 61439-1 where single-core double-insulated cables (such as NSGAFÖU) may be routed directly over grounded metal brackets ahead of overcurrent protective devices with zero risk of a ground fault or phase-to-phase short.
• Adiabatic short-circuit current factor (k) is the thermal capacity constant (143 A.s^(1/2)/mm2 for 90 °C 3GI3 EPR rising to 250 °C per IEC 60364-5-54, versus 115 A.s^(1/2)/mm2 for 70 °C PVC) used to calculate the maximum prospective fault current (Isc = k · S / √t) a single-core busbar lead can survive.

When to Upgrade from Unscreened NSGAFÖU to Screened NSGAFCMÖU.

While unscreened NSGAFÖU Cable is ideal for 50/60 Hz AC busbars, DC battery racks, and electroplating rectifiers, modern 690 V and 1,000 V IGBT / SiC variable frequency drives (VFDs), wind-turbine nacelle converters, and railway propulsion cubicles switch at 2 kHz to 16 kHz with voltage rise times (dv/dt) exceeding 5,000 V/us.

When unscreened single-core phase leads (U, V, W or DC+ / DC-) run inside a converter cabinet or along a locomotive underframe, their high-frequency electric field couples into nearby 24 V gate-driver fibers, CANbus harnesses, and current transducers (CTs). Specifying NSGAFCMÖU Screened Single-Core Wire solves three high-frequency converter hazards:

1. Controlled Phase-to-Ground Capacitance & Field Containment: The >= 85% tinned copper braid screen confines 100% of the radial electric field inside the 3GI3 EPR dielectric, eliminating corona discharge against sharp steel cabinet corners at 1.8/3 kV and 3.6/6 kV.
2. Low Surface Transfer Impedance (ZT ≤ 15 mOhm/m at 10 MHz): Terminating the NSGAFCMÖU copper braid with 360-degree EMC earth clamps at both ends provides a low-inductance return path for high-frequency common-mode currents, cutting radiated cabinet EMI by > 55 dB (TEBAOFLEX Lab, 2026).
3. Earth-Fault Touch Protection: If mechanical damage penetrates the outer 5GM2 jacket, the grounded copper screen trips the converter earth-fault relay immediately.

View full-size ampacity chart

Switchgear Busbar Ampacity at 45°C Ambient (A). grouped bar data: 16 mm2 Core: NSGAFÖU 90C (A) 96, H07V-K 70C (A) 68; 35 mm2 Core: NSGAFÖU 90C (A) 156, H07V-K 70C (A) 110; 50 mm2 Core: NSGAFÖU 90C (A) 194, H07V-K 70C (A) 134; 95 mm2 Core: NSGAFÖU 90C (A) 297, H07V-K 70C (A) 207; 150 mm2 Core: NSGAFÖU 90C (A) 401, H07V-K 70C (A) 275.Source: DIN VDE 0298-4 & TEBAOFLEX Thermal Rise Lab 2026.

Source: DIN VDE 0298-4 & TEBAOFLEX Thermal Rise Lab, 2026.

Complete NSGAFÖU 1.8/3 kV Dimensional, Ampacity & 1-Second Short-Circuit Table.

[ORIGINAL DATA] Using our testing method and test setup on 2026 production batches of NSGAFÖU 1.8/3 kV Cable, we compiled the dimensional, 20 °C DC resistance (IEC 60228 Class 5 tinned copper), free-air ampacity (30 °C and 45 °C cabinet ambient per DIN VDE 0298-4), and 1-second adiabatic short-circuit withstand current (Isc, 1s = 143 × S) table below.

Cross-Section (NSGAFÖU).

1x1.5 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 13.7
• Nominal Outer Diameter (mm).: 6.0
• Net Copper Weight (kg/km).: 14.4
• Approx. Total Weight (kg/km).: 55
• Ampacity at 30 °C (A).: 30 A
• Cabinet Ampacity at 45 °C (A).: 26 A (vs 18 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 0.21 kA

1x6 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 3.39
• Nominal Outer Diameter (mm).: 7.9
• Net Copper Weight (kg/km).: 57.6
• Approx. Total Weight (kg/km).: 115
• Ampacity at 30 °C (A).: 63 A
• Cabinet Ampacity at 45 °C (A).: 55 A (vs 38 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 0.86 kA

1x16 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 1.24
• Nominal Outer Diameter (mm).: 10.3
• Net Copper Weight (kg/km).: 153.6
• Approx. Total Weight (kg/km).: 235
• Ampacity at 30 °C (A).: 110 A
• Cabinet Ampacity at 45 °C (A).: 96 A (vs 68 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 2.29 kA

1x35 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 0.565
• Nominal Outer Diameter (mm).: 13.4
• Net Copper Weight (kg/km).: 336.0
• Approx. Total Weight (kg/km).: 460
• Ampacity at 30 °C (A).: 179 A
• Cabinet Ampacity at 45 °C (A).: 156 A (vs 110 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 5.01 kA

1x50 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 0.393
• Nominal Outer Diameter (mm).: 15.8
• Net Copper Weight (kg/km).: 480.0
• Approx. Total Weight (kg/km).: 630
• Ampacity at 30 °C (A).: 223 A
• Cabinet Ampacity at 45 °C (A).: 194 A (vs 134 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 7.15 kA

1x95 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 0.210
• Nominal Outer Diameter (mm).: 20.2
• Net Copper Weight (kg/km).: 912.0
• Approx. Total Weight (kg/km).: 1,130
• Ampacity at 30 °C (A).: 341 A
• Cabinet Ampacity at 45 °C (A).: 297 A (vs 207 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 13.59 kA

1x150 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 0.132
• Nominal Outer Diameter (mm).: 24.5
• Net Copper Weight (kg/km).: 1,440.0
• Approx. Total Weight (kg/km).: 1,740
• Ampacity at 30 °C (A).: 461 A
• Cabinet Ampacity at 45 °C (A).: 401 A (vs 275 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 21.45 kA

1x240 mm2

• Max DC Resistance at 20 °C (Ohm/km).: 0.0817
• Nominal Outer Diameter (mm).: 29.8
• Net Copper Weight (kg/km).: 2,304.0
• Approx. Total Weight (kg/km).: 2,720
• Ampacity at 30 °C (A).: 632 A
• Cabinet Ampacity at 45 °C (A).: 550 A (vs 378 A PVC)
• 1-Second Short-Circuit Rating (Isc, 1s).: 34.32 kA

For multi-core heavy-duty field feeder cables connecting to these switchgear panels, see our NSSHÖU, NSSHKCGEÖU & NSHXÖU Heavy-Duty Rubber Cable Guide and NSSHÖU & H07RN8-F FAT Testing & PO Checklist.

All lab tests follow IEC, DIN VDE, and ISO 9001 quality rules.

Key Takeaways & Frequently Asked Questions (FAQ).

Key Engineering Takeaways for Switchgear & Traction Busbar Wiring.

1. Use NSGAFÖU 1.8/3 kV for Unfused Switchgear Zones (DIN VDE 0100-520). Its dual-layer thermoset elastomer construction eliminates the need for external insulating conduits on busbar tap-offs up to 1,000 V AC / 1,500 V DC.
2. Exploit the +41% Ampacity Advantage at 45 °C Cabinet Ambient. Sizing busbar jumpers with 90 °C NSGAFÖU instead of 70 °C H07V-K PVC allows a one-step reduction in copper cross-section and tighter 4 x D fixed bend radii.
3. Specify NSGAFCMÖU Inside High-Frequency IGBT / SiC Inverter Cubicles. Its >= 85% tinned copper braid screen suppresses dv/dt common-mode interference and prevents cabinet corona.

Frequently Asked Questions (FAQ).

Below are direct engineering answers grounded in DIN VDE and IEC test standards (2026).

Why is a 1.8/3 kV rated NSGAFÖU cable used inside 400V, 690V, and 1000V switchgear cabinets?

Under DIN VDE 0100-520 (Section 521.11), single-core wires installed ahead of the first overcurrent protection device (between main transformer busbars and air circuit breakers) must be inherently short-circuit-proof and earth-fault-proof. NSGAFÖU achieves this status in systems up to 1,000 V AC and 1,500 V DC by combining a 1.8/3 kV nominal voltage rating with dual-extruded 3GI3 EPR insulation and a flame-retardant 5GM2 polychloroprene outer sheath.

When should I specify screened NSGAFCMÖU instead of standard NSGAFÖU?

Specify NSGAFCMÖU when routing single-core power leads between high-frequency IGBT or SiC frequency converters, DC link capacitor banks, active front-end rectifiers, or railway traction motors. Its >=85% tinned copper wire braid screen contains radiated PWM electromagnetic interference and safely drains capacitive common-mode currents to ground.

Can NSGAFÖU be installed directly on grounded metal cable trays or steel cabinet walls?

Yes. Because NSGAFÖU carries a dual-layer 1.8/3 kV elastomer wall tested at 6.0 kV AC for 5 minutes under DIN VDE 0250-602, it is certified for direct contact with grounded metallic switchgear frames, busbar supports, and rail vehicle chassis without risk of earth faults.

How much higher is the ampacity of NSGAFÖU compared to standard H07V-K PVC panel wire?

Because NSGAFÖU uses 90 C rated 3GI3 EPR insulation instead of 70 C PVC, its current-carrying capacity at a typical 45 C internal switchgear cabinet ambient is 41% to 45% higher than an identical cross-section of H07V-K PVC wire per DIN VDE 0298-4.

Request a Custom NSGAFÖU or NSGAFCMÖU Factory Quote.

Designing IEC 61439 switchgear panels, VFD inverter cabinets, or railway traction jumpers? Contact the TEBAOFLEX Engineering Team or reach us via WhatsApp +86 185 9591 3361. We supply full reels and cut-to-length NSGAFÖU 1.8/3 kV Cable and NSGAFCMÖU Screened Single-Core Wire across 1.5 mm2 to 300 mm2 with 6.0 kV / 11.0 kV AC routine FAT certificates under our DIN VDE Cable Standards program.