AC, DC circuit can apply a cable?

AC and DC circuit is not combined with a cable, the main reason is that the AC or DC loop are independent of the system, when a combination of AC and DC cables, AC and DC interfering each other, the insulation resistance of the DC current is reduced; at the same time, insulation system, and the exchange is connected the system between the two old friends, easy to cause a short circuit, DC cannot be combined with a cable.