Capacitor sign convention
I hope this is the correct answer that you need:

There are 2 types of capacitors, polarized and not polarized. 

The polarized capacitor has its signs on it. If you switch them and connect the capacitor - to the wire +, then the capacitor will get charged with negative voltage compared to ground. 

The not polarized capacitor charges depending on which end is connected to the + of the power supply. The + end will be positive compared to ground.

This of course is accepting the capacitor is in paralel to the power supply + and ground.