A crimp terminal is pressed onto the end of a wire so the wire can be connected to a stud, a terminal strip or another terminal. They look alike, but the shape of the tip decides where they fit and how they are handled. Here are the four tip shapes in the Allpum terminal range and how to read their sizes.
The tip shape decides where it fits
Ring
The round eye goes over a stud and is tightened down. The screw must come out to fit it, but the terminal cannot slip off even if the screw loosens a little. Available bare and insulated.
Fork
The open end slides under a loosened screw without taking it out, which speeds up work where wires are often removed and refitted. Available bare and insulated.
Blade
A flat pin that is inserted into a terminal strip and clamped by its screw. Supplied as an insulated terminal.
Quick disconnect
A female (REC) and male (TAP) pair that plug together and pull apart. Used where a connection must come apart without tools. Supplied as an insulated terminal.
Bare or insulated
On a bare terminal the crimp barrel is exposed metal; on an insulated terminal it is covered by a PVC sleeve. Ring and fork types come in both versions, while blade and quick-disconnect types are insulated. Use insulated terminals where the barrel could touch a neighboring terminal or metal surface, and finish bare terminals with insulation such as a terminal cap where needed.
Size ranges by type
| Type | Wire (SQ) | Stud | Sizes |
|---|---|---|---|
| Bare ring | 1.5 ~ 10 | 3 ~ 8 mm | 14 |
| Insulated ring | 1.5 ~ 6.0 | 4 ~ 6 mm | 11 |
| Bare fork | 1.5 · 2.5 | 3 ~ 5 mm | 4 |
| Insulated fork | 1.5 · 2.5 | 3 ~ 5 mm | 4 |
| Insulated blade | 1.5 · 2.5 | — (for terminal strips) | 4 |
| Insulated disconnect REC · TAP | 0.5 ~ 2.5 | — (female / male mating) | 8 |
Reading the size code
- Ring and fork 2.5-5R is a ring for 2.5 SQ wire and a 5 mm stud; 1.5-4Y is a fork for 1.5 SQ wire and a 4 mm stud. The first number is the wire, the second the stud diameter, and the letter the shape.
- Blade 152 and 153 are for 1.5 SQ; 252 and 253 for 2.5 SQ. Pin width (B) and length (L) differ within each wire size, so match them to the terminal strip.
- Quick disconnect REC is female and TAP is male. The 187 series is red, for 0.5–1.5 SQ wire; the 250 series is blue, for 1.5–2.5 SQ. Also check the size of the tab it will mate with.
Choosing step by step
- Look at what it connects to: a stud, a terminal strip or a mating tab.
- Decide whether it will be removed: often means fork or quick disconnect; held firmly means ring.
- Pick the size for the wire cross-section (SQ). Wire outside the range will not crimp properly.
- For rings and forks, match the hole to the stud diameter.
- Use an insulated terminal if the barrel could touch nearby metal.
Even with the right type and size, the connection is only as good as the crimp. Use a crimping tool suited to the terminal size, and tug the wire gently afterwards to confirm it holds. For joining wires end to end, look at butt sleeves; for covering spare wire ends, terminal caps.
