What is the difference between solid wire and stranded wire? What are their respective applications?

①. Core Structural Difference

• Solid wire (single-strand rigid wire, BV): A single thick copper conductor, not stranded.

• Stranded wire (multi-strand flexible wire, BVR): Made by twisting together multiple thin copper wires.

Project	Solid line	Twisted pair
Flexibility	Hard, prone to deformation after bending, and likely to break when repeatedly bent (metal fatigue)	Soft, capable of withstanding repeated bending and resisting vibration
Connector	Sturdy, easy to insert into the terminal block and screw terminal connection, and does not loosen easily.	The fine wires are prone to splitting. Generally, wire caps and tin plating are required to firmly secure them.
Cost	The processing is simple and the price is lower.	Multiple strands twisted together, with a higher cost
Electrical characteristics (power frequency 50/60Hz)	The current carrying capacities of the two are basically the same. At high frequencies, ordinary twisted wires do not significantly reduce the skin effect. Only special Litz wires are specifically designed to handle high frequencies.
Life expectancy	In a fixed wiring environment, it is resistant to oxidation and has a long lifespan; however, it is prone to breaking in a vibrating environment.	Longer fatigue resistance life under dynamic operating conditions

✅ Solid Wire (Hard Wire, BV): Fixed and permanent wiring

1. Hidden wiring inside walls for home decoration, sockets, main lighting circuits (most common)

2. Distribution boxes, conduits, cable routing fixed installation, straight line / few bends

3. Fixed wiring in industrial distribution cabinets, long-term static power supply circuits

4. Cost-sensitive, one-time permanent installation engineering wiring

Not suitable: Equipment that is frequently bent, shaken, or dragged.

✅ Twisted Wire (Soft Wire, BVR / Multi-strand Cable): Requires bending, vibration, and movement

1. Power lines for household appliances, extension cords, internal connections of power strips

2. Automotive wiring, ship wiring, robots, motion equipment, internal wiring of vibrating machines

3. Locations in distribution boxes where frequent bending and compact wiring are required

4. Audio cables, signal cables, instrument connection cables, etc. Soft and portable cables

5. Large cross-sectional power cables (Large hard wires are too stiff to be installed, commonly use twisted wires)