They may be small components, but terminal connectors are also essential ones for joining wires to equipment safely and reliably.
This crucial status does, however, mean that in the event of the wrong type of terminal connector being used (or even simply a poor crimping technique), there can be a range of adverse consequences, such as high resistance, overheating, and/or failure.
What Are Terminal Connectors?
You might have seen terminal connectors referred to as “crimp terminals”, “wire terminals”, or simply “terminals”. These components serve the purpose of terminating a conductor, so that it can be joined to a device, terminal block, or another cable.
Terminal connectors can be permanent or removable, and they see use across domestic, commercial, automotive, and industrial systems alike.
So, it isn’t only qualified electricians – working in accordance with the IET Wiring Regulations, or BS 7671 – who need to know what terminal connectors are. You might well be reading this, for instance, as a DIY enthusiast upgrading your home’s lighting, or someone involved in the maintenance of automotive, marine, or caravan electrics.
5 Types of Terminal Connectors and What They Are Used For
So, let’s take you through some of the most common forms that terminal connectors take, across the UK’s workshops, sheds, and vans.
We are aiming this guide largely at UK audiences. Nonetheless, much of what we state here is likely pertinent to you even if you are working elsewhere in the world.
- Ring Terminals
Ring terminals are distinguishable by their circular ring of metal at the end; this is designed to slip over a screw, stud, or bolt prior to tightening. They are available in such common sizes as M4, M5, M6, and M8 in the UK.
Once secured, ring terminals can be counted on to provide excellent vibration resistance. This makes them ideal for applications where it is crucial for connections not to come loose.
These terminal connectors, then, are much-valued as battery terminals in cars, leisure batteries, and solar setups. They also see use as earthing points and grounding studs, and for connecting to busbars, distribution blocks, or equipment with screw posts.
- Spade (Fork) Terminals
The open-ended “U” or fork shape of spade terminals allows for quick slide-on, slide-off attachment to screw terminals, without the need for full removal of the screw.
Female push-on spades, together with matching male tabs, are ubiquitous in UK automotive and white goods repairs.
You might see spade terminals being used for connecting to terminal blocks, relays, switches, and circuit breakers. They also see widespread use in automotive fuse boxes and lighting circuits, and for quick-disconnect wiring in control gear.
- Butt Connectors (Butt Splices)
These insulated, cylindrical crimp terminals are used to permanently join or splice two wires together end-to-end. This is typically done for the purpose of repairs or extending wiring.
Common applications for butt connectors encompass the likes of automotive loom repairs, the joining of wires in junction boxes, and marine or outdoor applications. In the latter context, heat-shrink versions are crucial for ensuring moisture resistance.
- Bullet Connectors
Typically consisting of a male pin and a female socket that push together, bullet connectors are extensively used in automotive, marine, and radio-controlled (RC) applications to join wires securely. All the while, these connectors also allow for easy, reusable, and fast disconnection.
Bullet connectors are commonly available in 4mm and 5mm diameters. They are frequently used for removable connections in car audio, trailer wiring, and lighting.
- Terminal Blocks (Choc Blocks/Strip Connectors)
The use of these screw-based blocks allows for the joining of multiple wires without crimping. They take a variety of forms, such as traditional screw choc blocks (polyethylene), modern lever connectors (such as “Wago-style” components), and push-in connectors.
For applications ranging from junction boxes and lighting circuits in domestic wiring, right through to control panels, distribution boards, and the extension of cables during home renovations, terminal blocks continue to show their worth during the 2020s.
Make Sure You Choose the Right Terminal Connectors for Your Needs!
If you’re reading this article with a view to using terminal connectors in a particular project of yours, you will need to take the time to select the component of the right size and type for the job. It will also be necessary to consider the environment in which the connectors will be used, in addition to ensuring your terminations comply with the aforementioned BS 7671.
Choose wisely, and make sure you crimp (or clamp) properly. Taking these steps will help ensure your connections stay safe and dependable for years to come.
