What Is a Crocodile Clip? Types and Selection Criteria

A crocodile clip is a metal clamp with spring-loaded, toothed jaws that attaches to a conductor or measuring point to make a temporary electrical connection.

A crocodile clip (alligator clip) is a metal clamp with spring-loaded, toothed jaws that attaches to a conductor, terminal or measuring point to make a temporary electrical connection. It is used on measuring instrument and test leads, in laboratory and workshop test set-ups, and on low-current supply leads for quick connections without soldering or screws. A crocodile clip is a temporary connection element; in permanent installations it does not replace a terminal block or a cable lug.

Types

Type	Construction	Use
Insulated crocodile clip	The body is covered with a plastic sleeve	Test and lab connections where clips lying side by side must not touch
Long-jaw (alligator-mouth) crocodile clip	Long body, wide grip	Holding thick terminals and leads
Test clip with banana socket	Has a socket at the back for a 4 mm banana plug; a measurement category is stated	Fitted to multimeter and test leads for measurements on the mains side

Selection criteria

Length and jaw opening: Choose a short clip for thin wires and circuit board leads, and a long-jaw clip for thick terminals and connection points. The jaw must grip the part without slipping.
Insulation: If several clips are used at the same time, insulated models reduce the chance of clips touching each other and causing a short circuit.
Measurement category and voltage: If you will measure at mains voltage, use a test clip marked with a voltage and measurement category (CAT II, CAT III, CAT IV). Use clips without this marking for low-voltage electronics, lab and test work.
Current: The jaw of a crocodile clip grips with a small contact area; it is not suitable for high-current connections.

Common mistakes

Measuring on the mains with a clip that has no measurement category: An insulating sleeve alone does not make use at mains voltage safe.
Leaving the clip as a permanent connection: The spring loosens over time, contact resistance rises and the clip can fall off under vibration.
Clipping onto the conductor's insulation: The jaw tries to pierce the insulation and the contact is unreliable; clip onto the bare end of the conductor or onto a terminal.

IEC 61010-031 sets the safety requirements for hand-held probe assemblies and test accessories for electrical test and measurement. A test clip to be used on the mains side should comply with this standard and state a measurement category.

Clips in the catalog

The Clips category has 7 active products: KSN 6 and Hirschmann 1. All are sold per piece.

Model	Length	Colour and stock code
KSN HWA-248A insulated crocodile clip, medium	35 mm	red `KSN9896`, black `KSN9896S`
KSN HWA-248B insulated crocodile clip, large	42.5 mm	red `KSN9897`, black `KSN9897S`
KSN HWA-243 alligator-mouth crocodile clip	66 mm	red `KSN9891`, black `KSN9891S`
Hirschmann HWA-263 crocodile clip AK-2S	—	`KSN9890`

The product names do not state a voltage or measurement category; for measurements on the mains side, Unit crocodile clips and test lead sets with CAT III 1000 V / CAT IV 600 V in the name (UT-C02A, UT-C05B, UT-L33) are in the Measuring Instrument Accessories category. The sockets that test leads plug into are in the Banana Jacks category.

Frequently asked questions

Is a crocodile clip the same as an alligator clip?

Yes. Both names describe the same clamp with spring-loaded, toothed jaws; in the catalog, "alligator-mouth" is used for models with a longer jaw.

Can a crocodile clip be used for mains measurements?

Only if it is a test clip that states a voltage and measurement category and complies with IEC 61010-031. Clips without this information are for low-voltage electronics and lab work.

Why are red and black clips sold separately?

Colour is for polarity: red is used on the positive lead and black on the negative lead. A circuit usually needs one of each colour.