Stranded Wire

Stranded wire is made up of multiple thinner wires, grouped together and insulated within a non-conducting enamel to form one cable. The use of multiple strands creates small gaps, which have several uses, such as increasing the flexibility of the wire and increasing resistance since the total cross section of the wire is not an uninterrupted metallic material.

Whilst stranded wire is made up of several wires grouped together, solid wire consists of a singular, core wire. Solid wire is a durable wire, thicker and heavier than stranded wire, with decreased dissipation; it is often used for outdoor applications or over long distances because of this. On the other hand, stranded wire, with increased flexibility, is often used for indoor applications. Solid wire, since it is easier to manufacture, is generally cheaper to purchase as opposed to a stranded wire equivalent.

Although theoretically you can mix stranded or solid wire – when, for instance, you prematurely run out of one type – this is not recommended. Mixing stranded and solid wire is a complex process, with many variables which may become hazardous or defective.

The types of stranded wire refer to the configuration of wires within the stranded wire. This includes:

• Concentric strand – in a concentric strand, layers of wire are wrapped around a core, central wire
• Bunch strand – with a bunch strand, there is no specific geometric pattern, with strands being more generally grouped together
• Rope strand – a rope strand involves groups of stranded wire which are twisted together to form a cable reminiscent of a rope
• Annular conductor – braided sets of strands surround a central, typically non-conductive wire
• Compact conductor – groups of bundled strands are compressed together to remove air pockets between the strands

Stranded wire gauge refers to the thickness of the wire – to measure this accurately, the wire must first be removed from its insulation. Once the stranded wire is exposed, an individual strand can be measured using a ruler or specialist wire measuring device. The diameter of the singular strand should then be multiplied by itself, before being multiplied by the number of strands in the wire. This will give the Circular Mil Area, or CMA, which can then be converted into the corresponding SWG value.

Common stranded wire applications include indoor applications. Because of the airspace within a stranded wire increasing dissipation, it is best suited to short lengths; it’s flexibility moreover means it can be easily manipulated – making it a suitable wire for circuit boards and electronic devices.

The benefits of stranded wire include easier installation, due to its flexibility, and a greater flex life because of its ability to endure increased vibration and bending as opposed to solid wire before it breaks. The damage inflicted on a stranded wire is often less severe than on a corresponding solid wire.

The disadvantages of stranded wire include it being a more expensive wire due to a greater tasking manufacturing process than solid wire. Moreover, it has a larger area of cross section compared to a solid wire, yet retains the same carrying capacity. Stranded wire can corrode due to capillary action, meaning it can falter, and the ‘skin effect’ created by magnetic fields can be amplified due to airspace between the strands.