Since I work in the commercial world, it’s very common for actors to wear lab coats and stethoscopes when called in for a doctor, nurse or pharmacist role. However, we did have a casting for “Firemen” types and some of the guys wore full on Firemen suits! Funny enough, the client LOVED this and called back many of the guys who were in full gear.
Yet when I was a casting assistant in the television world, if you came in dressed in full gear, it usually meant you were more concerned about your outfit then your acting. For TV, I would lightly “suggest” the role.
For example, if you’re auditioning for a nurse on Nurse Jackie, what kind of nurse are you? An ER nurse? A nurse in a private office? In these cases, nurses usually wear sneakers, a wrist watch and “warm colors,” ie. blues, pinks, light greens. So, what would I suggest you wear for a TV audition as a nurse? Sneakers, jeans or khakis, polo shirt in one of the above colors a wristwatch and hair in a pony tail as most nurses are on the go. If casting wants you to wear a lab coat and a stethoscope they will usually provide that for you at the audition and call back.