DLO cable is one of the most searched-for North American cable types we supply, and one of the most misunderstood. Here is what it is, what the ratings on the jacket mean, how the sizes work, and how it compares with welding cable.
What is DLO cable?
DLO stands for diesel locomotive. The cable was originally designed to carry power inside diesel-electric locomotives, where it has to cope with constant vibration, heat, oil and tight routing. Those same qualities make it a popular choice well beyond the railway, for any heavy-duty application that needs a flexible single-core power cable.
A typical DLO cable, such as the Super Vu-Tron Type DLO cable we stock, is built from:
- Conductor: finely stranded, tinned annealed copper for flexibility and corrosion resistance
- Insulation: premium-grade EPR (ethylene propylene rubber) rated to 90°C
- Jacket: black CPE (chlorinated polyethylene), resistant to oils, acids, alkalis, heat and abrasion
DLO cable ratings and approvals
One reason DLO cable is so widely specified is that a single cable carries several ratings, printed along the jacket:
- 2000 V Type DLO, the cable’s own locomotive rating
- UL Type RHH/RHW, 600 V, for use as building wire in North American installations
- CSA R90, 1000 V, the Canadian approval
- MSHA acceptance as flame resistant, important for mining equipment
- Sunlight resistant and rated for cable tray use on larger sizes, with FT4 flame rating available on request
Which rating applies depends on how the cable is being used and which code the installation must meet. If you are building equipment that needs to satisfy a UL or CSA inspector, the jacket marking is what they will check, so it is worth confirming the exact marking before you order. Our UL and CSA cable sourcing FAQs explain these approvals in more detail.
DLO cable sizes: 4/0, 2/0, 777 and more
DLO is sized in American Wire Gauge (AWG) and kcmil rather than square millimetres, which is often where UK buyers get stuck. In AWG, a larger number means a smaller cable until you reach 1/0. From there the “aught” sizes get bigger (1/0, 2/0, 3/0, 4/0), and above 4/0 sizes are given in kcmil, thousands of circular mils.
Our Super Vu-Tron DLO range runs from 10 AWG through to 777.7 kcmil:
| Size (AWG / kcmil) | Approx. metric (mm²) | Nominal O.D. (mm) | Amps in raceway (1) | Amps in free air (2) |
|---|---|---|---|---|
| 10 AWG | 5.3 | 6.60 | 40 | 55 |
| 8 AWG | 8.4 | 8.64 | 55 | 80 |
| 6 AWG | 13.3 | 10.16 | 75 | 105 |
| 4 AWG | 21.2 | 11.68 | 95 | 140 |
| 2 AWG | 33.6 | 13.21 | 130 | 190 |
| 1 AWG | 42.4 | 16.51 | 150 | 220 |
| 1/0 | 53.5 | 17.53 | 170 | 260 |
| 2/0 | 67.4 | 18.54 | 195 | 300 |
| 3/0 | 85.0 | 20.57 | 225 | 350 |
| 4/0 | 107.2 | 22.10 | 260 | 405 |
| 262.6 kcmil | 133.1 | 25.40 | 296 | 467 |
| 313.3 kcmil | 158.8 | 26.92 | 326 | 522 |
| 373.7 kcmil | 189.4 | 27.94 | 362 | 591 |
| 444.4 kcmil | 225.2 | 31.24 | 400 | 652 |
| 535.3 kcmil | 271.2 | 34.04 | 445 | 728 |
| 646.4 kcmil | 327.5 | 36.83 | 493 | 815 |
| 777.7 kcmil | 394.1 | 38.10 | 546 | 904 |
(1) Based on 90°C conductor and 30°C ambient temperature under the US National Electrical Code, for no more than three current-carrying conductors in raceway, cable or earth. (2) Single conductor in free air, 90°C conductor and 30°C ambient, per the National Electrical Code. Metric sizes are approximate conversions. Dimensions are nominal. Always apply the derating factors and rules that apply to your installation.
So a 4/0 DLO cable, the size we are asked about most, is roughly a 107 mm² conductor rated at 260 A in raceway or 405 A in free air under those conditions.
Where is DLO cable used?
Beyond locomotives, DLO cable is used for:
- Telecom power supply and battery connections
- Mining and earth-moving equipment
- Shipyards and marine power
- Motor leads and generator connections
- Flexible power leads that need to run through conduit or raceways
DLO cable vs welding cable
DLO and welding cable look similar and are often confused. Both are flexible single-core cables with fine copper stranding, but they are built for different jobs.
Welding cable is designed for the secondary circuit of a welding set, usually with bare copper conductors and a 600 V rating. DLO has tinned conductors for better corrosion resistance, a higher voltage rating and multiple UL and CSA listings, which makes it the better choice where the cable forms part of a permanent power installation that has to meet North American codes. If your application calls for a listed power cable, DLO is usually the one to specify.
Frequently asked questions about DLO cable
What does DLO stand for?
DLO stands for diesel locomotive. It is a flexible, rubber-insulated power cable first developed for diesel-electric locomotives.
Is DLO cable UL and CSA approved?
Yes. The DLO cable we supply is UL listed as Type RHH/RHW (600 V) and CSA certified as R90 (1000 V), alongside its 2000 V DLO rating and MSHA acceptance.
What is the ampacity of 4/0 DLO cable?
Our 4/0 Super Vu-Tron DLO cable is rated at 260 A in raceway and 405 A as a single conductor in free air, based on a 90°C conductor and 30°C ambient under the US National Electrical Code. Your installation conditions may require derating.
Can DLO cable be used as welding cable?
It can be used in some welding applications, but welding cable is usually more flexible and is the standard choice for welding leads. DLO is better suited to listed power circuits and permanent installations.
Can I buy DLO cable in the UK?
Yes. Quadrant Cables holds UL and CSA approved DLO cable at our Manchester distribution centre, cut to the lengths you need, with delivery across the UK and Europe. For other heavy-duty flexible options, see our guide to rubber cord cable.
Speak to the Quadrant Cables team
Need UL or CSA approved DLO cable, fast? Tell us the size, length and approvals you need and we will confirm availability and send a quote. Call us on +44 (0)161 879 9898 or contact us online, or view the full DLO cable specification.
Quadrant Cable Services Ltd, Unit 2 Crown Business Centre, George Street, Failsworth, Manchester M35 9BW.
