While working on selections of wire, I was introduced to the "current rating" of wires. Is this current rating dependent on voltage as well?
Example: A 10 AWG wire is rated to handle up to 30 A. Does it also depend on voltage levels as well like (100 V, 30 A) and so on?
Also, is there any significant difference between silicone and PVC wires of the same gauge (example: 10 AWG silicone vs 10 AWG PVC insulation wire)?
Any input on how to select wire size?
The voltage rating is related to the type and thickness of the insulation. Very high voltage wire may not be able to handle as much current because the thick insulation will slow down the heat dissipation.
The current ratings in the tables are based on what they consider to be an acceptable temperature rise. They do not consider voltage drop, and voltage drop is often a more important factor. A common beginner mistake is to ignore the voltage drop.
The current rating tables are a good starting point, but you do need to take the installation environment into account as well. Most tables are a convenient rule of thumb guide for common types of wire with standard temperature ratings; only the datasheet for your particular wire will be able to tell you exactly what you need to know. The voltage ratings and current ratings are not intrinsically related, but voltage rating will influence the material and thickness of the insulation, which will have some maximum temperature rating. The current flowing through your wire will heat it up, and that heat needs to be released to the environment through the insulation.
In your case, silicone-insulated wire is generally more flexible than PVC-insulated wire and has a wider range of operating temperature, but is more expensive and more difficult to find. You need to look at the whole system to make a well-informed decision. Aside from finding an appropriate wire for the voltage/current, you need to be thinking about:
