0.5 square means that the cross-sectional area s of the cable is 0.5 square millimeter. According to the formula of circular area s and diameter d: S = 1/4 π d 2, we can know that:

d=√(4S/π)

=2√(S/π)

=2√(0.5/3. 14)

About 0.8 mm

Extended data:

Wires and cables refer to materials used for power, electricity and related transmission purposes. Usually, products with few cores, small product diameter and simple structure are called wires, those without insulation are called bare wires, and others are called cables; A conductor with a larger cross-sectional area (greater than 6 square millimeters) is called a large cable, and a conductor with a smaller cross-sectional area (less than or equal to 6 square millimeters) is called a small conductor, which is also called a distribution wire.

Wires and cables mainly include bare wires, power cables for wiring and electrical equipment, cross-linked cables and communication optical cables.

Common failure causes:

1, insulation is affected with damp:

This kind of situation is very common, which usually occurs at the cable joint in the direct buried or exhaust pipe. For example, unqualified cable joints and joints made in humid climate conditions will make water or steam enter the joints and form water branches under the action of electric field for a long time, which will gradually destroy the insulation strength of cables and cause failures.

2, chemical corrosion:

When cables are directly buried in acid and alkali areas, the armor, lead skin or outer sheath of cables are often corroded. Due to long-term chemical corrosion or electrolytic corrosion, the protective layer will fail, which will also lead to cable failure. Chemistry: The cable corrosion of the unit is quite serious.