There are basically three types of lugs:
Plain type: It is used for general purpose seamless electrical terminals where installation characteristics are not required. They are available in various pad widths to accommodate most stud sizes.
With sight hole: This is used as the general purpose terminal and permits inspection of cable insertion depth and solder flow. The advantage of the sight hole is that it does not create a weak spot under severe vibration.
Connectors: These are seamless connectors for wire size #8 through 4/0AWG and are also available as flared or chamfered barrels.
Mechanical lugs are available bolted with two screws or with four screws. They are typically ring shaped and are usually made of high-grade electrolyte copper or aluminum. They are suitable for big wires and cables and are available in three varieties: plain type, sight hole type (which is similar to the plain types, but with a bigger hole), and the connector type.
Mechanical lugs are suitable for brass lightning protection and where there may be plenty of vibration. These are also designed to be corrosion and abrasion resistant. The EX Burndy mechanical lugs act as conductors made with aluminum or copper. They can be single hole, double hole, or stacked with screws.
Compression lugs are stud-type input power connection that are generally made of high conduction wrought copper or aluminum. They may have one or two holes in order to provide automatic connection and also come with an electro tin plate to reduce corrosion. The different types of Blackburn compression lugs available are one hole, two holes, and speciality compression lug. A short barrel lug has only the single-holed compression lug, which is usually used for switch gears and motor controls. They are mainly preferred for telecommunication equipment and devices, welding equipment, and power distribution equipment.
Ilsco manufactures grounding lugs of varied types such as ground clamps, ground grid system, ground strip, flexible braid, and bronze service post among others. Grounding lugs are heavy duty lugs that are used for wires on transformers or steel structures. They have a threaded stud that fits all types of transformers and offers high clamping force, which prevents the wire from pulling out the grounding lugs. These are generally made of bronze material and connects the grounding conductor to the grounding electrode. They are useful for assembling a grounding kit with an integrated cable lug. The single-holed grounding lug is suitable for grounding line hardware or switchgear to a transmission structure. They are the most important part of the solar photovoltaic systems.
While compression lugs and grounding lugs are suitable for small scale connections, mechanical lugs support big electrical connections. Mechanical lugs are significantly larger than the other two, while compression lugs are preferred by people who like tinkering with the mechanical fitting themselves. Mechanical lugs are also used in automobiles, while grounding lugs are preferred for both indoor and outdoor uses on flexible metallica and liquid tight conduits when copper or aluminum installations are required.
Different types of lugs offer different conductivities and some can conduct electricity much better than others, irrespective of the material used (copper or aluminum). Choosing the right lugs can help in preventing accidents from fire or electrocution.