Viiu,
14/3 wire.... NM-B cable, Romex example of? Not sure why you spent the extra money for an isolated grounding type receptacle in the first place.
In your case the isolated ground contact of the receptacle works the same as a regular grounding type receptacle. No isolation was needed.
It's on a dedicated circuit. To be more specific, do I need to pull a 14/2 wire to replace the 14/3 wire?
I assume, hope, the safety equipment grounding conductor was terminated on the ground bar in the electrical panel the branch circuit is fed from. If this is the case you need not do anything, just change out the receptacle.
I should point out though if an electrician installed the branch circuit wiring and the isolated grounding type receptacle and used a metal rough-in box for the recept he should of also connected the safety equipment grounding conductor, wire, to the metal box.....
If a plastic box was used everything is code compliant, but in this case by code you must use a non conductive recept cover plate.....
On an isolated grounding type recept the ground contact of the recept is not connected to the metal supporting back strap of the recept. By code the strap must also be connected to a safety equipment ground wire. (The strap of the recept is connected to the metal box by support screws which is connected to an additional safety equipment grounding conductor.)
Jim
