A pair of solid, soft-drawn copper conductors are insulated with rugged polyvinyl chloride (PVC). Each conductor is individually rated to operate up to 60°C and 600 V in wet or dry locations. These black and white conductors are twisted together with a suitable lay.
Mine telephone wire is suitable for use as a communication cable for mine telephone hook-ups.
Make sure you can talk to people on the surface while you’re inside a mine.