Two-hole copper compression lugs
Two-hole copper compression lugs use a tubular compression barrel and a palm with two mounting holes to terminate copper conductors at bolted electrical connections. Typical applications include transformer terminal pads, switchgear and busbars.
US$ 17.90/Kg
Technical specifications
| Parameter | Specification |
|---|---|
| Hole diameter | both clearances |
| Hole spacing | Centre to centre, from mating pad |
| Palm width | usable landing area |
| Barrel length | qualified crimp pattern |
Metric and American conductor size chart
Metric and American designations are listed separately. Available lug and conductor combinations depend on the approved drawing and tooling.
| Size system | Nominal conductor sizes for enquiry |
|---|---|
| Metric (mm²) | 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400 |
| American (AWG) | 8, 6, 4, 2, 1, 1/0, 2/0, 3/0, 4/0 |
| American (kcmil) | 250, 300, 350, 400, 500, 600, 750, 800 |
Product overview
The second mounting bolt constrains rotation when both holes match the mating pad. Equal bolt diameters alone leave the centre spacing and palm envelope to be matched.
Product variants
Palm configurations differ in hole clearance, hole centre spacing, width and length. Barrel length is a separate design variable.
Crimp barrel and conductor compatibility
The nominal cable size identifies the conductor family. The cable construction and bare conductor diameter determine physical barrel fit. The approved die and crimp sequence apply to the particular conductor and lug combination.
Copper grades and finishes
C11000 electrolytic tough-pitch copper and C10200 oxygen-free copper are candidate grades for conductive components. The approved drawing governs the grade and finish for the ordered part. Tin-plated and bare copper finishes are identified separately on the quotation.
Manufacturing and inspection
A typical tubular lug is formed from a tube blank. Forming creates the palm, after which the hole pattern is produced and the edges are deburred. Drawing inspection covers dimensions such as barrel bore, insertion depth and palm geometry. Electrical and mechanical qualification applies to the complete termination with its specified conductor and tooling.
Two-hole pad geometry
A two-hole palm has to match the equipment pad as a complete bolt pattern. The critical measurements are both hole diameters, their centre spacing, the distance from each hole to the palm edge, and the clearance from the inner hole to the barrel shoulder. This last dimension can affect socket access even when both bolts enter the pad freely. A transformer pad drawing can also show whether the lug overhangs the pad or fouls an adjacent phase barrier.
How the barrel and palm work together
A tubular cable lug brings together two interfaces with different mechanical requirements. Inside the barrel, the conductor strands occupy a defined bore and are compressed by the approved die. At the palm, the lug bears against an equipment contact surface under the specified bolted assembly. The design has to accommodate both interfaces within the space available in the enclosure. A suitable conductor fit therefore addresses only one part of the selection.
The transition between the barrel and palm also affects the installed shape. Its position determines how closely the cable can approach the mounting face and how much room remains around the fastener. A smooth dimensional transition helps the component fit the intended assembly, but photographs seldom show all of the critical clearances. A side view and a plan view together show the relationship between the mounting hole, barrel axis and available contact area.
For repeat purchasing, the complete configuration is more useful than a description such as copper lug or heavy-duty lug. Conductor size, cable construction, mounting hole, barrel length, palm geometry and finish define a reproducible component. This combination allows the purchasing team to compare quotations against the same intended termination.
Cable construction and barrel selection
The conductor within a power cable can be assembled in several ways. Two cables carrying the same nominal cross-section may have different strand counts and different bare bundle diameters. Compaction can change the outer shape of the bundle, while fine stranding changes how the bundle behaves during preparation and insertion. The applicable lug and tooling instructions identify the conductor constructions supported by a particular termination.
Barrel bore is consequently a functional dimension. The cable must enter to the intended depth while remaining within the range covered by the approved crimp process. An oversized barrel does not automatically accommodate a smaller conductor satisfactorily, and a conductor that physically enters a barrel does not automatically qualify the connection. The relationship between the conductor, barrel wall and die geometry determines the finished compression.
For a manufactured cable assembly, the cable part number is useful alongside its nominal size. It connects the lug selection to a specific conductor construction and insulation system. That information also helps control future substitutions. If a purchasing change introduces a different cable, the existing lug and tooling combination can be reviewed against the revised construction before the assembly is released for production.
Understanding dimensional information
A dimensional table should identify what each measurement represents. Overall length describes the complete lug from the palm end to the barrel entrance. Barrel length describes a different portion of the component, and usable insertion depth may differ again where an internal feature limits conductor travel. Treating these values as interchangeable can lead to an incorrect strip length or an unexpected cable exit position.
Palm width is measured across the flattened terminal portion. Palm thickness affects the fastener stack, while the hole centre position determines where the lug sits on the equipment stud. The distance from the hole to the barrel shoulder matters when the mounting pad is narrow or the tightening tool needs to approach close to the barrel. A drawing can show these relationships more clearly than a single product photograph.
Dimensional units also belong with the values. Metric conductor area is expressed in square millimetres, while lug dimensions are commonly expressed in millimetres. AWG and kcmil describe American conductor sizes. Inch dimensions may describe an American mounting fastener. Keeping these units explicit allows the component to be compared with the cable and equipment documentation without assuming that every number represents the same kind of measurement.
Contact surfaces and fastening arrangement
The palm forms the bolted contact surface at the equipment terminal. Its usable footprint depends on the shape and dimensions of the mating pad. A wide palm can still have limited support if it extends beyond the pad, and a barrel shoulder can prevent full seating if it interferes with an adjacent feature. The equipment assembly drawing establishes the intended position of the lug and the associated hardware.
The fastening arrangement includes the bolt or stud, washer arrangement and any specified locking components. These items contribute to the complete joint. Their selection and tightening requirements come from the equipment or connection specification. A general catalogue page cannot establish one torque value for every stud size, fastener material and terminal construction.
Cable routing influences this interface as well. A cable that is forced sideways after the palm has been attached can apply a load to the terminal. Suitable support and a planned cable path allow the lug to sit in its intended position. This is particularly relevant for large conductors, which can occupy substantial space and resist being moved into a tight bend near the barrel mouth.
Applications in machinery and control equipment
Industrial machinery often uses bolted power connections in a limited enclosure space. Straight two-hole tubular lugs provide a defined cable entry direction and two mounting points. Their suitability depends on the terminal layout, conductor construction and qualified connection system. The cable path may pass through ducts, supports or protective sleeves before reaching the termination.
Control equipment can contain terminals of several different sizes within the same assembly. The lug palm and fastening tool need enough space around each connection, and the cable arrangement must respect the equipment layout. A compact lug can simplify the mechanical arrangement where its conductor capacity and tooling are suitable. The available space for a protective cover can be as important as the bare lug envelope.
Production cable assemblies also benefit from consistent identification. A drawing or bill of materials can connect the cable length, lug configuration, orientation and protective sleeve to one assembly revision. When several similar lugs are used in the same panel, that identification helps distinguish a change in stud size from a change in conductor size. Both differences may be difficult to recognise from a packed component alone.
Application planning for large conductors
Large power conductors introduce handling considerations beyond the dimensions of the bare lug. The cable bend radius, cable weight and location of the first support influence how the completed termination fits. An overall length that appears suitable on a component drawing may leave too little room once the insulated cable and its protective covering are included.
A straight lug establishes the direction of the cable immediately beyond the barrel. Where the enclosure requires the cable to turn, the bend begins outside the termination according to the cable assembly requirements. The available routing space can therefore influence whether a straight or angled product is appropriate. The related angled lug pages describe alternative geometries for that equipment layout decision.
Tooling space is another consideration for larger barrels. The crimp head and dies can require more room than the finished lug occupies. Assembly planning includes the sequence in which the conductor is inserted, the crimp is completed, the protective sleeve is positioned and the palm is secured. An accessible finished connection does not necessarily provide access for every earlier manufacturing operation.
Material, finish and document identification
The copper grade and finish form part of the ordered component specification. A grade designation identifies the material requirements associated with the approved drawing. A finish description identifies the surface treatment, while the agreed inspection criteria define how that finish is assessed. These characteristics can be recorded separately so that a coating change is distinguishable from a change in the underlying material.
Material documentation, dimensional inspection and finish records each address a different aspect of the supplied part. Their usefulness depends on their connection to the ordered configuration and production batch. A report describing another size or a different finish does not establish the characteristics of the delivered component. The purchase documentation can identify which records accompany the order.
Product qualification adds another layer of information because it concerns the complete connection under defined test conditions. The lug, conductor and installation tooling must be identified within that evidence. Product descriptions can refer to standards where applicable, while claims of certification require the relevant supporting documentation for the actual supplied product. This distinction helps buyers understand the scope of the records associated with their order.
Variants within a two-hole lug family
Several variants can share a two-hole layout while serving different assembly requirements. Barrel length, palm width, mounting hole and finish can change independently within the limits of the design. The word tubular describes the barrel construction, and the two-hole designation describes the mounting arrangement. Neither term by itself gives every dimension needed to identify the part.
A family table is most useful when it connects each configuration to a clear drawing or part reference. That reference allows the same item to be reordered even when other similar products are listed nearby. It also helps avoid assuming that all stud sizes are available for every conductor cross-section. The combinations offered for an order depend on the available design and its qualification.
For buyers comparing straight, two-hole and angled products, the starting point is the mating equipment. The mounting pattern and cable approach establish the geometry. The conductor and installation requirements then establish the barrel and tooling combination. The related product links provide a way to compare these different lug forms within the Copper Cable Lugs range.
Short-barrel and long-barrel copper lugs
Barrel length affects the space occupied by the completed cable termination. A short barrel can suit a compact panel where the distance between the busbar and the cable support is limited. A long barrel provides additional axial length for the crimp pattern associated with that design. The number and location of crimps follow the qualified tooling instructions for the individual lug. Barrel length alone does not establish the current rating of the connection.
The cable also needs room beyond the barrel mouth. This space accommodates the cable bend radius, insulation sleeve and first mechanical support. A termination can fit on the mounting stud while leaving insufficient room for the cable to approach without side load. Overall length, barrel length and cable exit position therefore belong together in an equipment layout review.
Single-hole palm geometry and stud clearance
A two-hole palm provides two bolted attachment points. Its geometry includes the clearance hole, palm width, palm thickness and distance from the hole centre to the barrel transition. These dimensions affect washer seating, contact area and access for tightening tools. The palm should seat on the intended equipment contact face without interference from the barrel shoulder or adjacent insulating parts.
The nominal stud designation refers to the fastener. The clearance hole is a separate dimension, allowing the lug to pass over that fastener. A metric M8 stud and an 8 mm clearance hole are different specifications. American fasteners likewise use nominal inch dimensions, with the actual clearance governed by the approved drawing. Conductor cross-section and mounting hole size remain independent selection parameters.
Metric, AWG and kcmil conductor designations
Metric conductors are commonly described by nominal cross-sectional area in square millimetres. American conductors use AWG and, for larger sizes, kcmil. These designations help identify the cable, but a nearby numerical conversion does not establish that the same lug accepts both conductors. The barrel and crimp tooling must be compatible with the conductor construction being terminated.
The strand count, individual strand diameter and compaction affect the shape and diameter of the bare bundle. Flexible and compacted conductors can behave differently during insertion and compression. A useful product specification therefore identifies both the nominal size and the supported cable construction. The nominal sizes listed on this page are enquiry designations, with the supplied combination governed by its drawing and installation instructions.
Bare copper and tin-plated finishes
Bare copper and tin-plated copper are finish options that serve different purchasing specifications. The ordered finish applies to defined surfaces and has its own inspection criteria. On a tin-plated lug, coating thickness and coverage are distinct characteristics. A visually bright surface alone does not establish coating thickness or acceptance against an agreed finish specification.
The mating terminal surface is part of the joint design. Plating on the lug does not by itself establish suitability for every conductor material, enclosure environment or equipment terminal. Material compatibility and the complete connection specification govern the application. Packaging and handling also matter because damage or contamination on the palm can affect the condition of the contact surface before assembly.
Panel, switchgear and busbar applications
In distribution panels, a straight tubular lug joins a cable to a bolted terminal while allowing the conductor to approach along the barrel axis. The space occupied by the palm and tightening tool must fit within the terminal compartment. Cable management determines the position of the first support and the path of the insulated cable away from the connection.
Switchgear and industrial busbar assemblies can use several lugs close together. Palm width, insulation clearance and cable routing then become interdependent. The application drawing establishes phase spacing and any protective barriers. Where cables run vertically, the support arrangement carries their weight so that the lug and stud connection are not used as the sole cable support.
Crimp barrel, insertion depth and tool access
The barrel has to accommodate the stripped conductor to the intended insertion depth. The cable preparation length follows the lug and cable assembly instructions. A strand bundle that enters only part of the required depth changes the conductor engagement within the compression zone. Inspection of preparation and insertion is therefore an assembly control before the crimp operation.
Tool access deserves its own layout check. A die set occupies space around the barrel, and a powered crimping head may need room to approach from a particular direction. Some assemblies are crimped before the palm is bolted to the equipment. Others allow crimping in position. The assembly sequence depends on the equipment layout, cable handling requirements and approved tool.
Dimensional inspection and production records
Dimensional inspection can cover the barrel bore, outside diameter, usable insertion depth, overall length, palm width and mounting hole position. The approved drawing defines the dimensions and tolerances that determine acceptance. Material records and finish inspection provide additional information about the ordered component.
Electrical and mechanical qualification concerns the assembled termination. Its result depends on the lug, conductor and tooling combination as well as the test method. A dimensional inspection report establishes conformity with the inspected drawing characteristics. Qualification records address the performance conditions covered by the particular test. The quotation identifies the documentation agreed for the supplied order.
Dual-hole copper terminals for transformer pads
Transformer connections bring together the cable termination, the terminal pad and the equipment enclosure. A two-hole lug occupies a longer mounting footprint than many single-hole configurations. The available pad length therefore influences where the barrel starts and where the cable can leave the terminal compartment. The equipment drawing provides the reference for both mounting holes and the permitted contact area.
The inner bolt, closest to the barrel, needs room for its washer and installation tool. A barrel shoulder that lies too close to this bolt can complicate assembly even where the clearance holes match. The outer bolt needs adequate seating area toward the end of the palm. These relationships explain why a two-hole terminal is identified by its full drawing rather than the conductor size and bolt diameter alone.
Transformer terminal layouts also vary in the orientation of the pad. The same lug can point in different directions depending on how the equipment presents the mounting face. The cable path, protective barriers and access cover determine whether the straight barrel suits that layout. Where the required cable approach changes, an angled lug provides a separate configuration for engineering assessment.
Hole spacing and tolerance relationships
Centre spacing is the distance between the centres of the two mounting holes. It is independent of the clearance diameter. A pair of holes can have the correct individual diameter while their spacing prevents the lug from fitting the mating studs. The approved drawing therefore includes both dimensions and the tolerances needed for the intended assembly.
With fixed studs, the lug must pass over both locations simultaneously. With separate bolts through a pad, the hole pattern must still permit assembly without forcing the palm out of its intended position. The dimensional relationship involves the lug and mating equipment together. A catalogue description such as standard spacing provides insufficient detail unless it is tied to an identified dimensional reference.
Palm flatness and hole location are also related to the manufacturing process. Forming the palm and producing the holes must result in the geometry shown on the approved drawing. Dimensional inspection can measure the mounting pattern from defined reference surfaces. This approach makes it possible to compare a first article, a production sample and a repeat order using the same acceptance basis.
Two-hole lug ordering examples
A busbar assembly may use several conductor sizes while retaining a common terminal pad pattern. Each cable size then needs an appropriate barrel, while the two-hole palm must match the shared equipment interface. The resulting family can contain parts that look similar at the palm but differ substantially at the barrel. Clear part identification helps distinguish these configurations during assembly.
Another equipment range may use the same conductor construction with different terminal pads. In that case, the barrel requirements can remain similar while the mounting pattern changes. Hole spacing, clearance diameter and palm width become the distinguishing features. The product reference links these dimensions to the finish and inspection documentation agreed for the order.
For recurring supply, the purchase order can reference the approved part and drawing revision. This provides a stable identity for the complete component and allows changes to be reviewed explicitly. A revised equipment pad or a substituted cable can then be assessed against the relevant interface. Cable Glands India quotations identify the configuration covered by the offered price and the agreed production documentation.
Frequently asked questions
Does every two-hole lug use the same bolt spacing?
Hole clearances and centre spacing vary with the equipment pad and its drawing.
What does the quotation cover?
The quotation identifies the lug configuration, conductor and stud sizes, finish, order quantity and any agreed inspection documentation.
How is the mounting hole sized?
The clearance diameter follows the mating fastener and lug drawing. The palm also provides room for washer seating and contact with the equipment pad.
Which crimp tool and die are compatible?
The installation instructions for the selected lug and conductor identify the approved tool, die and crimp sequence.
Can I use the same lug for different conductor constructions?
Compatibility is assessed for each conductor construction. Nominal area alone does not establish compatibility with the barrel or die.
How do I specify tin plating?
The finish specification defines the tin thickness, significant surfaces and inspection criteria.
What records can I request with an order?
The quotation can identify the material, dimensional and finish records agreed for the order.
Can a custom drawing be quoted?
Custom geometry can be reviewed against a dimensioned drawing and the mating equipment layout. The quotation can include first-article inspection where agreed.
Request a quote
Cable Glands India provides quotations by lug configuration, conductor size, mounting geometry, finish and order quantity.