What Is Diesel Locomotive Cable (DLO)?
Diesel locomotive cable (DLO) is a rugged, highly flexible power cable designed for harsh industrial environments. While it was originally developed for diesel-electric locomotives, it’s now widely used across industries like mining, oil and gas, marine, and renewable energy thanks to its durability and ability to handle movement, vibration, and tight routing.
Construction and Ratings
DLO is built with a dual-extruded design that gives it both strength and flexibility:
- Insulation: EPR (Ethylene Propylene Rubber)
- Jacket: TS-CPE (Thermoset Chlorinated Polyethylene)
- Conductors: Tinned copper, finely stranded (Class I)
This combination provides strong resistance to oils, chemicals, heat, flame, moisture, and abrasion—making it well-suited for tough environments.
Typical electrical ratings:
- Voltage: 2000V
- Temperature:90°C (dry)
- 75°C (wet)
- UL RHW-2 versions: Rated 90°C in both wet and dry conditions
DLO can be installed in conduit, cable tray, ducts, or troughs, and performs reliably in both wet and dry locations. Its flexibility also makes it ideal where cables need to bend, move, or fit into tight spaces.
Common Applications
Although it started in rail, DLO has become a go-to cable for many heavy-duty applications.
Originally used for:
- Powering traction motors in diesel-electric locomotives (where a diesel engine drives a generator, and electric motors turn the wheels)
Today it’s commonly used in:
- Locomotives: Generator-to-motor power connections
- Drilling rigs: Portable power and control circuits
- Marine & offshore: Shipyards and drilling platforms
- Transit systems: Rail cars and auxiliary power systems
- Industrial facilities: Motor leads, jumper cables, and power distribution
- Backup power: UPS systems, battery banks, and generator leads
With UL RHH/RHW-2 and CSA RW90 ratings, DLO is widely accepted for power and motor applications. Larger sizes (typically 1/0 AWG and above) are also tray-rated, making them suitable for industrial installations.
DLO vs. Welding Cable
DLO and welding cable often look similar, but they’re built for different purposes.
- DLO cable:Dual-layer insulation
- Higher voltage rating (up to 2000V)
- More resistant to flame, oil, and mechanical damage
- Welding cable:Single-layer insulation
- Designed for secondary circuits on welders
- Lower voltage rating
Because of its durability, DLO is sometimes used as a heavy-duty alternative to welding cable—especially in high-current applications where extra protection is needed.
How to Terminate DLO Cable
DLO uses very fine strands, which means standard lugs won’t work properly. It requires connectors specifically rated for flexible conductors.
Key tips for proper termination:
- Use flex-rated lugs designed for finely stranded cable
- Strip insulation carefully to avoid damaging strands
- Choose compression lugs with a chamfered barrel entry
- Do not bend or fold strands to make them fit
Per NEC 110.14, conductors finer than standard Class C must use connectors listed for flexible conductors. Following this ensures a solid connection and helps prevent overheating or failure.
Cost and Performance
DLO is more expensive and heavier than standard building wire like THHN or XHHW. That’s mainly due to:
- The fine-stranding process
- Dual-layer thermoset insulation and jacketing
- More complex manufacturing and curing
That said, you’re paying for performance. DLO holds up in environments where standard cable won’t—making it a reliable long-term solution in demanding applications.
Key Takeaway
DLO cable is built for conditions that push equipment to the limit. Its flexibility, durability, and high voltage rating make it a top choice for industrial power applications where reliability matters.
Looking for DLO Cable?
We stock a wide range of UL-listed DLO cable in multiple sizes, colors, and reel lengths—ready to ship.
Reach out for pricing, technical support, or cut-to-length options.
