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Diesel Locomotive (DLO) cable was originally developed in the early 1900s to support the electrical demands of diesel-electric locomotives. These systems required a cable that could reliably deliver high currents to traction motors while withstanding severe conditions—intense vibration, oil saturation, high temperatures, and constant mechanical stress. Built for this punishing environment, DLO cable quickly proved to be more than just a locomotive solution.
Today, its rugged construction, flexibility, and 2,000-volt rating have made it a trusted choice in a wide array of heavy-duty applications. From drilling rigs and earth-moving equipment to battery systems, generators, and mobile power units, DLO cable delivers long-lasting performance in environments where standard wire would degrade or fail. Its combination of electrical strength and mechanical resilience continues to meet the evolving demands of modern industrial power systems.
What Makes DLO Cable Unique?
DLO cable is engineered with two layers of protection and a finely stranded conductor to handle both mechanical stress and electrical demand. Its 2,000-volt rating —standard across all sizes—positions it well above most conventional building wire and portable cords.
The conductor consists of rope-lay tinned copper strands that allow for easy bending and maneuverability during installation, even in tight conduit spaces or confined tray systems. Tinning offers the added benefit of corrosion resistance, which is critical in outdoor, damp, or high-sulfur environments.
Surrounding the conductor is a thermoset rubber insulation layer made from ethylene propylene rubber (EPR), which provides strong dielectric performance and thermal stability. A second outer layer made from chlorinated polyethylene (CPE) adds resistance to oil, abrasion, sunlight, chemicals, and flames. Both layers are designed to withstand tough operating conditions without cracking, shrinking, or becoming brittle over time.
Where It’s Used
Though the cable’s origin lies in the rail industry, today it supports many power systems that require durability, high voltage tolerance, and flexibility:
- Mining and drilling operations
- Wind and solar farms
- UPS systems and battery banks
- Shipyards and offshore platforms
- Mobile generators and construction trailers
It’s also used in panel wiring, grounding systems, and tray applications. Because many DLO cables are dual-rated as RHH/RHW-2, they are permitted under NEC Article 310 for use in conduit, ducts, and cable trays, even in wet locations.
Construction and Features
- Conductor: Fine-stranded tinned copper (ASTM B172)
- Insulation: EPR for high dielectric strength and thermal resistance
- Jacket: CPE for abrasion, oil, chemical, UV, and flame resistance
- Operating temperature: up to 90°C (continuous), 130°C (emergency), and 250°C (short circuit)
- Cold weather rating: down to −40°C
- Flame testing compliance: IEEE 1202/FT4, UL 1685
- Available sizes: 14 AWG to 1111 kcmil, with uniform 2,000 V rating across all sizes
Installation Considerations
While DLO cable is exceptionally flexible and rugged, its fine-stranded conductor calls for precision during termination. When stripping insulation, care must be taken not to damage or misalign the individual copper strands. Frayed or bent-back strands can compromise electrical contact and create heat points. Most flex-rated compression lugs for DLO include a flared barrel opening to help guide the conductor smoothly into place—but successful termination ultimately depends on careful handling in the field.
DLO is heavier and more expensive than conventional cables like THHN or XHHW, due to its high strand count and dual-layer rubber jacketing. The additional cost reflects its premium construction—intended for environments where reliability and flexibility are non-negotiable.
Minimum bend radius should be respected per ICEA S-95-658/NEMA WC70 guidelines. This ensures long-term mechanical integrity during and after installation.
Finally, DLO is manufactured with a standard black jacket. Clear external labeling is recommended in multi-circuit applications to support safety and maintenance.
How It Compares
| Feature | DLO Cable | Welding Cable | RHH/RHW-2 Building Wire |
|---|---|---|---|
| Voltage Rating | 2,000 V | 600 V | 600–1,000 V |
| Flexibility | Very High | High | Low–Moderate |
| Conductor Type | Tinned Copper, Fine-Stranded | Bare Copper, Flexible | Copper, Medium-Stranded |
| Insulation System | Dual Layer (EPR + CPE) | Single Rubber or PVC Layer | XLPE |
| Temperature Range | −40°C to 90°C (continuous) | ~−20°C to 90°C | −25°C to 90°C |
| Durability in Harsh Envs | Excellent | Fair | Moderate |
| Termination Method | Flex-Rated Compression Lugs | Clamp or Welding Lugs | Standard Lugs |
| Typical Use Case | Industrial, Rail, Mobile Power | Welding Machines | Building Feeders |
Summary
DLO cable is a premium-grade power cable built to perform in the harshest conditions. With a 2,000 V rating, flexible fine-stranded core, and rugged dual-layer insulation, it offers an unmatched combination of reliability, mobility, and environmental resilience.
Whether it’s routed through a tray in a wind farm, dropped into conduit for a mining installation, or coiled in a mobile generator trailer, DLO is built to last—delivering clean, consistent power in places most other cables can’t.
