No it's not.
If you have an open starter and are going to utilize the line terminals for your control power where is the
fusing at if you dont field install it?
That'd be a new one on me.
I've never worked with/on a
motor starter that was not in an enclosure. I've modified and repaired plenty of motor starters... I've even built a few
motor starters from scratch.
To me, field installed is outside the enclosure for the motor starter. The majority have control circuit fusing inside the motor starter enclosure. The ones that did not, used a remote power source for the control circuit, such as PLC controlled starters, with control circuit protection at the power supply... but the majority of the PLC controlled starter setups I've worked on used the starter incorporated control circuit and the PLC just switched the circuit.
A standard off-the-shelf motor starter (MCC bucket or stand-alone enclosure) will have control circuit protection in the enclosure (with the exception of small motor starters that the motor GF/SC protection is adequate for the control circuit protection).