History and Development
Whilst there is an awareness of electricity dating back many hundreds of years, it was not until the late 1800’s that we saw the greatest progress in electrical engineering. This development turned it from a scientific curiosity into an essential tool for modern life and in fact, became a driving force for the second industrial revolution.
The need to distribute electricity in turn drove the development
of insulated wires, subsequently vital to the massive growth in
automotive, electric and electronic industries.
Wire was developed in two main types, solid core and stranded
core, but why?
Solid core wire is cheaper to manufacture than stranded wire and is used where there is no need for flexibility in the wire.
Solid wire also provides strength and protection against the environment.
Multi-strand wires are more flexible and can be routed more easily than wires with solid cores. For instance, it wouldn’t be much good if the wire to your table lamp was not flexible (the origin of the term 'Flex').
But there are drawbacks, unlike solid core wire, the strands tend to spread and splay making it awkward to get them into terminals.
Another being that the individual strands can be quite fine, so if you attempt to tighten a screw down on them (for instance in a connector block), the wires can break leaving a weak connection. One potential solution is to solder the ends of the wire, but this is time consuming, expensive and can result in burns to the wire insulation and your skin!
There were other needs; for instance wires may need to be joined but the joint has to be detachable for maintenance or repair. Electric motors often have terminal posts for connecting wires to – this requires the end of the wire to finish in a ring.
This all drove the development of a wide range of fittings that are attached by squashing them (in a precise way) onto the end of the wire. We will cover this in detail later.
These fittings have a fairly wide range of names including crimps, crimp connectors, crimp terminals, terminals or lugs. We will call them crimp connectors.
In the UK, crimp connectors are used mainly in control panels, car accessory fitting and the like – This is because the majority of domestic and commercial electrical installation work is done using solid core wire (Flat twin and earth wire) which can be connected straight into terminals.
It’s rather different on the continent. There they use multi-strand wire on far more applications, so have a much greater need to use crimp connectors to terminate the wiring.
So let’s now take a look at the different types of crimp connectors commonly used.