DTL-F Square Head Bimetal Cable Lug 10-500mm2

Product Overview

The DTL-F is the square-palm member of our DTL bimetal lug family. Where the standard DTL carries a round palm, the F variant terminates in a flat square head — a shape chosen when the terminal pad is narrow, when lugs must sit side by side without fouling, or when the joint has to resist rotation under load.

The aluminium barrel and copper palm are joined by induction-assisted friction welding, producing a metallurgical bond instead of a mechanical contact. There is no crevice for moisture to enter, which is what removes galvanic corrosion at the copper-aluminium interface. Conductor range is 10 mm2 to 500 mm2, covering DTL-F-10 through DTL-F-500 in the dimension table below.

Type testing follows IEC 61238-1, and the product carries CE marking. Rated for low and medium-voltage systems up to 10 kV.

Why a Square Palm

It Fits Where a Round Palm Will Not

Look at the dimension table and one figure stands out: palm width W is consistently narrower than barrel diameter D — 14 mm against 16 mm on the DTL-F-10, 32 mm against 40 mm on the DTL-F-500. That is deliberate. A round palm has to be wide enough in every direction to clear the bolt hole; a square palm puts material only where it carries current and clamping force.

The practical result is a lug that lands on narrow terminal pads and tightly pitched busbar drillings where a round-palm lug of the same rating would overhang its neighbour. On a crowded switchboard, this is often the difference between a clean termination and a reworked one.

Flat Edges Resist Rotation

A single-hole round palm can pivot around its bolt if the joint is disturbed — during retightening, or when cable weight pulls on the termination. The square head's straight edges seat against adjacent hardware or the pad shoulder, so the palm stays where it was set. In panels where cables are dressed under tension, this keeps the contact face aligned instead of slowly twisting off-centre.

Larger Flat Contact Area for the Same Width

Square geometry uses its footprint more efficiently than a circle. Within the same palm width, the flat head presents more usable contact surface around the bolt hole, which spreads clamping pressure across a broader area of the mating busbar. Lower interface pressure per unit area means the joint is less prone to relaxation over thermal cycles.

Construction and Materials

Material Grades Stated on Certificate

The barrel is drawn from 1070 industrial-pure aluminium — chosen for ductility, so the barrel wall flows into the conductor strands during compression rather than cracking. The palm is T2/T3 electrolytic copper. Both grades appear on the mill certificate supplied with each batch, so a project QA engineer can verify the material instead of taking the claim on trust.

One Body Size Covers Several Conductor Sizes

A detail worth understanding before ordering: DTL-F-10, -16, -25 and -35 share identical external dimensions (D 16, W 14, L 87, S 4.2) and differ only in bore diameter d, which steps from 4.5 to 8.5 mm. The same applies to the 50/70/95 group and the 120/150 group.

Two consequences follow. First, the crimping die is shared across each group — fewer die changes on site. Second, you must order by conductor size, not by external appearance, because four different parts look the same in the hand. Every lug is stamped with its size for this reason; check the marking, not the shape.

Dual Corrosion Protection

The copper palm is tin plated against oxidation and salt spray. The aluminium barrel receives a chromate conversion coating and ships with anti-oxidation compound pre-filled in the bore, sealed under a cap. The pre-fill is intentional — brushing and greasing aluminium is the step most often skipped on site, and skipping it is a common reason aluminium terminations start heating up a year or two after commissioning.

Operating Temperature

Rated for continuous service from -40°C to 110°C. The number matters less as a headline than as a thermal-cycling claim: a friction-welded interface does not open as copper and aluminium expand at different rates, which is exactly where a bolted copper-to-aluminium contact eventually fails.

Where the DTL-F Is Used

• Compact distribution boards and MCC panels — narrow terminal pads and closely pitched busbar holes, where round palms overhang.

• Motor and drive terminal boxes — confined enclosures needing several terminations in a small footprint.

• Process plant and heavy industry — chemical, refinery, steel and mining installations combining humidity, contaminants and vibration.

• Retrofit work — replacing terminations on existing equipment where the original pad drilling leaves little clearance.

Installation Notes

1. Order and check by conductor size. Because one body size serves several conductor sizes, always read the stamped marking before crimping. A DTL-F-35 and a DTL-F-10 are indistinguishable by eye.

2. Brush the aluminium conductor. Aluminium re-oxidises within seconds of stripping. Wire-brush the strands and crimp promptly; the compound already in the bore seals the cleaned surface.

3. Match the hexagon die to barrel diameter D, not to the conductor size. An oversized die under-compresses the barrel and leaves joint resistance high.

4. Seat the square head flat and torque to the equipment manufacturer's figure. Confirm the palm sits flush before final tightening — the flat edges make misalignment easy to spot.

FAQ

What does the F in DTL-F mean?

F denotes the square head (flat square palm). A standard DTL has a round palm; the DTL-F terminates in a square one. Electrical performance and the welded bimetal joint are the same — the difference is palm geometry and where it can physically fit.

When should I choose DTL-F over a standard round-palm DTL?

Choose the square head when terminal pad space is tight, when several lugs must sit side by side, or when the termination needs to resist rotation. For open switchgear and substation work with generous pad clearance, the standard round-palm DTL is perfectly adequate and usually easier to source.

Why do several DTL-F sizes have the same external dimensions?

Sizes within a group (10/16/25/35, then 50/70/95, then 120/150) share one body and differ only in bore diameter. This lets one crimping die serve the whole group. Order and verify by the stamped conductor size — the parts are not interchangeable even though they look alike.

What conductor preparation is required before crimping?

Cut the conductor end square, strip to the barrel depth marked on the lug, and remove the oxide film with a wire brush. The bore already contains anti-oxidation compound, so no extra paste is needed. Insert the conductor fully until it seats, then crimp.

Which standards does the DTL-F meet?

Type testing follows IEC 61238-1, the international standard for compression connectors on power cables, and the product carries CE marking. Type test reports and material certificates are available on request for project submittals.