I am replacing 2 light switches that are in the same box each controlling a separate light, one was a dimmer switch and the other was a regular so now I want to replace both with new dimmer switches. But when I opened up the box there was a secondary black wire that connected the switches together. Do I still need to leave this 2nd black wire in place or can I remove it and put a nut on the end?
The wire that connected to both switches is likely the line (power source). One circuit and cable comes into the electrical box with a hot and neutral. The hot is connected to both switches, and then each switch has its own cable to the circuits they control. If you remove it, you likely won't have any power to your fixtures. The configuration will be the same regardless of if its a switch or dimmer.