If an electrical wire is exposed and could electrocute someone, what type of material should you use to cover the exposed wires?
Any form of insulator that won't melt easily. For example rubber.
Cut the circuit breaker or turn off the circuit, and repair the wire properly. You can use duck tape or electrical tape as a temporary fix. How many volts? If 120V RMS, it should be taken care of, but more than 240V RMS, you REALLY NEED to get a qualified electrician to repair it.