alligator clip
A spring-loaded metal clip, usually attached to a wire and used to create a temporary electrical connection.
alligator clip: spring jaw for fast temporary wire bonds
An alligator clip is a small spring-loaded clamp with two metal jaws that pivot open when you squeeze a lever or trigger, then snap shut with strong clamping force when released. The jaws are lined with serrated teeth or knurled surfaces to grip wire, cable lugs, or bare metal terminals firmly without damaging most conductors. Each clip typically weighs 10 to 50 grams and measures 25 to 75 millimeters long, depending on the current rating and conductor size it handles.
These clips earn their name from the resemblance of the hinged jaws and sharp teeth to an alligator's mouth. They attach to stranded or solid copper wire of 12 to 20 AWG gauge, or to heavier battery cables rated for 50 to 300 amperes in automotive and testing work. The internal spring maintains pressure even as metal relaxes or thermal cycling loosens mechanical bonds over weeks or months.
Variants and materials
Insulated clips have a plastic or rubber sleeve covering the metal jaw assembly, color-coded red for positive, black for negative, or yellow for ground in electrical testing. Bare metal clips offer better current flow but pose shock risk if touched while energized. Nickel-plated or tin-plated jaws resist corrosion in damp shops; copper-plated versions maximize conductivity. Specialized clips exist for high-frequency RF work, where capacitive loading matters, but most industrial use involves DC circuits under 300 volts.
The connection is purely mechanical and temporary, not soldered. This makes alligator clips invaluable in test benches, battery jumper cables, automotive diagnostics, and laboratory equipment where connections change frequently. However, the tooth contact area is small, and resistance builds up when jaws loosen or corrode; a properly seated clip typically adds 0.001 to 0.01 ohms to a circuit. High-current work demands tight clamping, clean metal surfaces, and periodic re-seating.
Common failure modes include broken springs, stripped teeth, loss of springback after years of use, and creep of the clip along the wire under vibration. In motorsport and high-reliability testing, engineers often solder a spade lug or ring terminal to the wire end and crimp it, then attach a clip to that termination rather than directly to bare wire, reducing slippage and improving repeatability.