Do you need a licenced electrician to hang conduit for low voltage cable?

In most places, for residential, no. For commercial, most jurisdictions require a contractors license for anyelectrical work. Where I live, there is a low-voltage license that is less than a full-blown electrical license that is used by fire alarm, security, and telecommunications contractors. The NEC and most jurisdictions define low voltage as less than 30 volts. Check with your local building department to be sure!