Cables and Wire

Cable... flex... lead... wire...
What do all these terms mean?

Single core equipment wire

single core wire

This is one solid wire with a plastic coating available in a wide variety of colours. It can be bent to shape but will break if repeatedly flexed. Use it for connections which will not be disturbed, for example links between points of a circuit board.

Typical specification: 1/0.6mm (1 strand of 0.6mm diameter), maximum current 1.8A.

Rapid Electronics: 1/0.6mm wire reels

Rapid Electronics: 1/0.6mm wire pack

Stranded wire

stranded wire

This consists of many fine strands of wire covered by an outer plastic coating. It is flexible and can withstand repeated bending without breaking. Use it for connections which may be disturbed, for example wires outside cases to sensors and switches. For general low current use in projects 7/0.2mm wire is a good choice. A very flexible version with many strands (called 'extra-flex') is used for test leads.

Typical stranded wire specifications:
10/0.1mm (10 strands of 0.1mm diameter), maximum current 0.5A.
7/0.2mm (7 strands of 0.2mm diameter), maximum current 1.4A.
16/0.2mm (16 strands of 0.2mm diameter), maximum current 3A.
24/0.2mm (24 strands of 0.2mm diameter), maximum current 4.5A.
55/0.1mm (55 strands of 0.1mm diameter), maximum current 6A, used for test leads.

Rapid Electronics: 7/0.2mm | extra-flex

'Figure 8' (speaker) cable

'Figure 8' cable consists of two stranded wires arranged in a figure of 8 shape. One wire is usually marked with a line. It is suitable for low voltage, low current (maximum 1A) signals where screening from electrical interference is not required. It is a popular choice for connecting loudspeakers and is often called 'speaker cable'.

Rapid Electronics: speaker cable

figure 8 cable
Photograph © Rapid Electronics

Signal cable

Signal cable consists of several colour-coded cores of stranded wire housed within an outer plastic sheath. With a typical maximum current of 1A per core it is suitable for low voltage, low current signals where screening from electrical interference is not required.

The picture shows 6-core cable, but 4-core and 8-core are also readily available.

Rapid Electronics: signal cable

signal cable
Photograph © Rapid Electronics

Screened cable

The diagram shows the construction of screened cable. The central wire carries the signal and the screen is connected to 0V (common) to shield the signal from electrical interference. Screened cable is used for audio signals and dual versions are available for stereo.

Rapid Electronics: screened cable

Construction of a screened cable:

screened cable

screened cable
stereo screened cable
Screened cable (mono and stereo)
Photographs © Rapid Electronics

Co-axial cable

This type of screened cable (see above) is designed to carry high frequency signals such as those found in TV aerials and oscilloscope leads.

Rapid Electronics: screened cable

coaxial cable
Photograph © Rapid Electronics

Mains flex

Flex is the proper name for the flexible cable used to connect appliances to the mains supply. It contains 2 cores (for live and neutral) or 3 cores (for live, neutral and earth). Mains flex has thick insulation for the high voltage (230V in UK) and it is available with various current ratings: 3A, 6A and 13A are popular sizes in the UK.

Mains flex is sometimes used for low voltage circuits which pass a high current, but please think carefully before using it in this way. The distinctive colours of mains flex should act as a warning of the mains high voltage which can be lethal; using mains flex for low voltage circuits can undermine this warning.

Rapid Electronics: mains flex

mains flex, 3 way
Photograph © Rapid Electronics

Rapid Electronics have kindly allowed me to use their images on this website and I am very grateful for their support. They stock a wide range of connectors and cables for electronics and I am happy to recommend them as a supplier.