Terminals and Connectors - What are the different types and when should I use them?
What is an Electrical Terminal?
It is a device attached to the end of a conductor to enable it to form a physical connection to another compatible device in order to reliably and safely pass electrical current or signals.
What are the different types of electrical terminals and connectors?
Bootlace ferrules, also commonly known as cord end terminals, are typically used on flexible multi stranded wire that is to be connected to a screw down type of terminal block or connector. They are available in 3 basic versions.
- Uninsulated Bootlace Ferrules
- Insulated Bootlace Ferrules
- Insulated Dual Entry Bootlace Ferrules (to terminate 2 wires in one terminal)
The benefits are as follows.
- Effectively converts a stranded conductor into a solid conductor, for a robust, reliable termination with a screw down style terminal.
- Prevents the conductor from fraying leading to conductor loss and reduction in current carrying capacity.
- Prevents conductor damage during handling, connection, or re-connection.
- Much faster, more convenient, and safer than tinning the ends with solder.
The insulated versions come in 2 main colour coding versions, French and German.
Pre-insulated Crimp Terminals are typically used for low voltage small conductor connections to a variety of different styles of electrical connector. By far the most common insulation material is PVC (or Vinyl) with typically a flared coloured vinyl entry to ease insertion of a stripped wire end.
The Red, Blue, Yellow colours correspond to the size of conductors they accommodate.
- Red is for 0.25 - 1.5mm ² or 22 - 16AWG
- Blue is for 1.5 - 2.5mm ² or 16 - 14AWG
- Yellow is for 4 - 6mm ² or 12 - 10AWG
Typical connector styles are as follows
- Ring Terminals
- Fork Terminals or Spade Terminals
- Pin Terminals
- Blade Terminals
- Hooked Blade Terminals
- Push-on connectors, fast-on or disconnect connectors (male and female)
- Bullet connectors (male and female)
- Butt Splices (for joining)
There are more specialist materials available including halogen free Polycarbonate and PA6.6 Nylon insulation. Vibration resistant designs incorporate an additional copper sleeve between the terminal insulation and the wire insulation which when crimped provides a more secure grip of the wire.
Available but less commonly used by electricians are uninsulated versions of these terminals.
Copper tube terminals also commonly referred to as copper lugs are heavy duty terminals for terminating power cables. These terminals are designed to carry significant electrical current and good crimping practice and secure termination is essential.
These heavy-duty terminals are designed for conductors from 1.5mm all the way up to 1000sq. mm and must be able to cope with sustained loads of the maximum electrical current the conductor is rated to.
They are made from seamless copper tube with a wall thickness specified such that the x-sectional area of the terminal exceeds that of the conductor itself ensuring its current carrying capacity. Typically, these are terminated with an indent style hand crimp tool for the smallest sizes, graduating to a ratchet hex die tool, and ultimately a hydraulic hex die tool for the larger sizes.
You must ensure you use the terminal manufacturers matched crimp tooling as small variances in terminal dimensions will have a very significant effect on the ultimate crimp tool pressure and the resulting crimp performance. Operator awareness of, and adherence to, the manufacturer’s crimp selection/tooling and installation instructions is critical for a safe and reliable termination.
Specialist Terminals
The previous sections covered the most common terminals used by electricians and are covered by our own brand expressTERM product range. There is also a wide array of other less common specialist terminals available for specific situations.
Our premier quality suppliers
Cembre,
Klauke
and
Panduit
in addition to the above, also offer solutions covering the following.
- German DIN 46228/4 bootlace terminals (a second German standard)
- Multi hole copper tube terminals
- 4-hole transformer copper tube terminals
- Angled copper tube terminals
- Narrow palm copper tube terminals
- Insulated copper tube terminals
- Copper pin terminals
- Colour coded copper tube terminals and splices
- C terminals or Sleeve Connectors (for tapping)
- Mechanical fixing lugs
- High voltage copper tube terminals
- Aluminium terminals
- Bimetallic terminals
We don’t list all these specialist terminals on our website, but we can provide you with help, information and pricing.
Terminal Tooling
With such a wide array of terminals there is a correspondingly vast array of tooling available from low-cost hand tools right up to battery or hydraulic tools to terminate the largest terminals.
The most important fact to remember is that terminals and tooling are two parts of a “system” and using the wrong tooling or mixing tooling manufacturer and terminal manufacturer breaks this system and will give unreliable results.
Call us on +44 (0)141 941 3689, or email sales@expresselectrical.co.uk with your inquiry today!