Solid-Core Versus Stranded Wire

One of the most frequently asked questions in the field of electrical engineering, about the difference between solid and stranded wire and which one is best for various applications, is actually surprisingly straightforward. Both solid and stranded wire have benefits and disadvantages that make them each suited to particular uses over other applications. Read on to find out everything you need to know to make the best-informed decision for your project.

heater core wire

What’s the Difference?

Solid wire is made up of a single solid core of conductive material which can vary in diameter from around a millimetre up to several centimetres. Wire thickness is referred to as ‘gauge’. Stranded wire, by contrast, consists of multiple lengths of solid wires of a smaller gauge bundled together. Due to the simple nature of solid-core wire, it is generally much cheaper to produce and purchase than a stranded wire of the same gauge.

However, the practicalities of a solid core also restrict the range of gauges available, so it is predominantly manufactured on the smaller end of the scale. Conversely, the fact that the core is solid does allow for a lower gauge of wire than would be required for a stranded wire to achieve the same current rating due to tiny gaps between the separate strands inside a piece of stranded wire.

Advantages and Disadvantages

Stranded wire can be more prone to corrosion. Between the strands of wire there are small spaces which can become clogged with tiny amounts of water which has nowhere to go, leading to corrosion-related failure over time. This is worsened by the much greater amount of surface area available inside a stranded wire by comparison to a solid wire of the same gauge. Solid-core wire, on the other hand, presents fewer problems related to corrosion, but this kind of wire is prone to fatigue and eventual failure in conditions of regular vibration, flexing and movement.

Implications

As a result of these advantages and disadvantages, solid wire is evidently the more sensible choice for applications where the wire remains stationary, such as in domestic electrical set-ups, and in scenarios where the wire will be exposed to environmental elements. Solid-core wire is also used in electrical breadboards and for building circuit prototypes due to the solid nature of the core making it much easier to handle and insert into small holes.

Stranded wire, by contrast, demonstrates much greater durability than a solid wire of similar gauge. This makes it ideal for industrial and commercial applications where the wire will be subject to frequent movement, such as in car-building robot arms or as heater core wire, where the stranded wire functions to lower physical stress in pressure vessels and piping. Heater core wire has to be specially manufactured using a nickel-based alloy to be able to withstand such pressure.

The flexibility of stranded wire also makes the use of it a wise and, indeed, necessary choice for situations where the wire will regularly be flexed, particularly in consumer electronics such as appliance cables, headphones and speaker wires. The additional flexibility also makes stranded wire suitable and easier to use on occasions where it must be routed through a constricted space.

On the other hand, the manufacturing process for stranded wire is more complex and necessitates higher-tech machinery than would be required for simple solid-core wire, driving up the cost of the finished product.