What's the cause of leaking voltage in this cable?

This is a 7x1 cable, made by some unknown company:

When I connect 220V to two of these wires, other wires also get ~60V. At first I thought I have some short circuit, there so I used a multimeter and checked all wires two by two and there was no short circuit.

How and why does voltage "leak" from two wires to other wires in this cable?

Answer

The wires have a significant capacitance to each other. If your only load on the end is the high impedance of your DMM (at least 1M, often 10M), then it's quite expected to be able to read such a voltage on unconnected wires. When you put a heavier load on them, the voltage will drop to near zero.