Insulated wire

An insulated wire, comprising:

• a conductor;
• a flame-retardant insulation layer that comprises a resin composition including a flame retardant and is arranged around the conductor;
• a water-blocking layer that is arranged directly on the flame-retardant insulation layer;
• and
• a flame-retardant layer that comprises a resin composition including a flame retardant and is arranged directly on the water-blocking layer,
• wherein each of the resin composition of the flame-retardant insulation layer and the resin composition of the flame-retardant layer comprises polyolefin, and the water-blocking layer has a water absorption of not more than 0.5% at saturation,
• wherein an outer diameter of the conductor is not less than 1.0 mm and not more than 20.0 mm,
• wherein a thickness of the water-blocking layer is not less than 25 μm and not more than 150 μm,
• wherein a total thickness of the flame-retardant insulation layer and the flame retardant layer is not less than 300 μm and not more than 500 μm,
• wherein the resin composition of the flame-retardant layer comprises not less than 150 parts by mass and not more than 250 parts by mass of the flame retardant with respect to 100 parts by mass of a resin,
• wherein the water-blocking layer does not contain the flame retardant, and
• wherein a ratio of the thickness of the water-blocking layer to a combined thickness of the water-blocking layer and the flame-retardant insulation layer is not more than 18%.