How to Specify a Custom DLO Lug Jumper: Gauge, Lugs, Length, Tolerance

A lug jumper is a length of cable with a lug on each end. Once it is bolted into a battery cabinet, UPS, or switchgear bus, every detail left off the spec becomes a field call or a rework. This guide lists what belongs on a complete DLO lug jumper specification, in the same order the Conversions Tech Custom Cable Builder walks you through.

1. Conductor size and the ampacity basis

Start with the conductor size and say which ampacity you sized it to. Most jumper specs reference NEC Table 310.16, which lists allowable ampacities for not more than three current-carrying conductors in a raceway, cable, or earth at a 30 °C ambient. For copper, the 75 °C and 90 °C columns read as follows:

Type DLO carries a 90 °C rating, but the equipment terminal usually limits you. Under NEC 110.14(C), conductors larger than 1 AWG or circuits over 100 A are generally held to the 75 °C column unless the equipment is listed and marked for higher temperature terminations. Ambient correction, bundling, and duty cycle are the engineer of record's call. The builder displays both the 75 °C and 90 °C values for the size you pick so the basis is visible on the quote and the drawing. It is not a substitute for the project's load calculation.

Instant pricing covers 8 AWG through 4/0. DLO from 262 to 777 kcmil and THHN at 750 kcmil are quoted, with a budget price shown during configuration so you can carry a number while the formal quote is prepared.

2. Conductor type and stranding class

Name the cable type and the stranding class, not only "flexible cable." Type DLO is a 2 kV flexible power cable built on fine, rope-lay stranded tinned copper. Manufacturer data sheets such as Southwire's describe its conductor as Class I stranding per ASTM B172, with EPDM insulation and a CPE jacket. Cables that carry the dual RHH/RHW-2 marking are recognized for 90 °C wet and dry locations. Tinned strands resist corrosion in battery rooms and outdoor enclosures.

The class matters because NEC Chapter 9, Table 10 defines Class B and Class C as the reference stranding for building wire. Anything finer, including Class I and Class K, is outside what a standard compression lug is evaluated for.

3. Lugs rated for fine-strand conductors

This is the line item most often left off a spec and the most common source of failed jumpers. NEC 110.14 requires connectors and terminals for conductors more finely stranded than Class B and Class C to be identified for the specific conductor class or classes. UL 486A-486B, the standard for wire connectors, requires connectors tested with finer classes to be marked with those classes on the connector, the unit container, or an enclosed information sheet. As NEMA's bulletin on fine-stranded connections notes, an unmarked connector is limited to Class B, Class C, or single input wire stranding.

A standard lug crimped on fine-strand DLO can end up under-compressed, then run hot or loosen under vibration and thermal cycling. Specify "flex-rated" lugs that are marked for the cable's class. In the Custom Cable Builder, selecting DLO automatically assigns flex-rated tinned copper long-barrel lugs. They are priced 10% above standard lugs, and the drawing calls them out by class.

4. Hole pattern, stud size, and tongue angle

Define each end separately. A jumper from a battery post to a bus bar often needs different terminations at each end.

• One-hole lugs: state the stud size. The builder offers 1/4 in through 5/8 in.
• Two-hole lugs: state stud size and center spacing. Common patterns are 1/4 in on 5/8 in centers for telecom grounding, and the NEMA patterns of 3/8 in on 1 in and 1/2 in on 1-3/4 in centers. Two-hole lugs resist rotation on bus connections.
• Tongue angle: 0, 45, or 90 degrees. A 90 degree lug often saves a tight bend radius at a cabinet wall. A 45 degree lug can clear an adjacent terminal.
• Relative orientation: if both ends are angled, note whether the tongues point the same way. The 3D preview shows it before you order.

All Conversions Tech jumper lugs are tinned copper long-barrel compression lugs that receive two crimps. The long barrel gives more contact length and room for the second crimp. If you are matching lugs to existing hardware, the lug applications guide and the copper battery cable lug collection list the stock patterns.

5. Length and how it is measured

"36 inches" means different things to different shops. Specify the measuring convention. Conversions Tech measures lug jumpers from bolt-hole center to bolt-hole center, which is the dimension that matters when the jumper lands on fixed studs. For two-hole lugs, the reference is the hole nearest the cable unless your drawing says otherwise. That convention is printed on every engineering drawing the builder generates.

6. Tolerance

Standard tolerance on lug jumpers is ±1/4 in up to 36 in and ±1% above 36 in. If your equipment needs tighter, request a quote before releasing the PO.

7. Jacket and heat shrink color

DLO jackets are typically black, with polarity or function identified by colored heat shrink over the lug barrel. Red and black for DC positive and negative is the common convention. Equipment grounding conductors follow NEC 250.119, so confirm colors against the project drawings. The part number encodes jacket and shrink color.

8. Labels and identification

Options include printed heat-shrink ID labels, self-laminating wrap labels, and sequential numbering matched to the one-line or rack elevation.

9. Packaging and paperwork

Specify the paperwork with the parts: individual poly bags labeled with part number, lot, and barcode; kitted sets by cabinet or string; a certificate of conformance; and a lot test report. Each is a line item, so list only what your quality plan requires.

The spec checklist

From spec to part number

Every configuration in the builder resolves to a permanent part number that encodes the spec. For example, CTJ-10DLO-1H38-1H38-036-BKRD is a 1/0 DLO jumper with a 1-hole 3/8 in lug on both ends, 36 in long, black jacket, red shrink. Put that number on the PO and the next order matches the first. Each build also generates an engineering drawing with title block, bill of materials, dimensions, and tolerances that can go straight into a submittal package. Volume breaks apply at 10, 25, and 100 pieces, and approved trade accounts can order on PO and net terms.

Ready to spec one? Open the Custom Cable Builder, configure your jumper, and download the drawing before you send the PO. Assemblies are Assembled in USA from components that carry their own UL listings.

FAQ

Can I use standard compression lugs on DLO cable?

Not unless the lug is identified for the cable's stranding class. NEC 110.14 requires terminations for conductors finer than Class B and Class C to be identified for that class. DLO is fine-strand, so the builder assigns flex-rated lugs whenever DLO is selected.

Which ampacity column should I use?

It depends on the equipment terminals and installation conditions. Many terminals are rated 75 °C, which limits the conductor to the 75 °C column even though DLO is rated 90 °C. The builder shows both values. Your engineer of record makes the final call.

How is jumper length measured?

From bolt-hole center to bolt-hole center. Tolerance is ±1/4 in up to 36 in and ±1% above.

Is the finished assembly UL listed?

The cable and lugs carry their own UL listings. The finished assembly is not represented as UL listed. A certificate of conformance and lot test report are available.