Table value or nameplate?
Both, for different jobs. Conductors and short-circuit protection come from the table; overload comes from the nameplate. Swapping them is the classic motor-circuit error.
Every motor has two current figures and they usually disagree. The code is emphatic about which one to use where, and the rule is neither arbitrary nor a trick question once you see what each number is for.
Step-by-step
- Look up the table FLC for your horsepower and voltage in NEC 430.248 (single-phase) or 430.250 (three-phase).
- Read the nameplate FLA off the motor itself, along with its service factor.
- Size conductors at 125% of the table value for a continuous-duty motor.
- Size overload from the nameplate — 125% where the service factor is 1.15 or greater, otherwise 115%.
Why two sources
They describe different things, and the code uses each where it belongs.
The table value is a standardised figure for a motor of that horsepower and voltage, and it is deliberately generic. Conductors and short-circuit protection size from it precisely because it is generic: the wiring should not need redoing when the motor is replaced with a different make of the same size, and the installation should be safe for any motor that could legitimately go in that spot.
The nameplate value is the actual current of the actual motor in front of you. Overload protection sizes from it because overload protection has exactly one job — keeping this motor's windings from running hot — and a generic number cannot do that job. A setting based on a table value that happens to run high would let the real motor cook.
So: size the wiring for the class of motor, size the overload for the individual.
The gap between them is not an error
An efficient modern motor commonly draws less than its table figure. It is tempting to treat the smaller nameplate number as the more accurate one and size everything from it, which produces conductors and protection tighter than the code intends. The gap is the margin the standardised value is supposed to carry.
Starting current is a third thing
Neither figure describes the first second. Locked-rotor current can be six times full-load or more, which is why motor short-circuit protection may be set far above the conductor ampacity: it has to ignore inrush and still clear a fault. A breaker much larger than the conductor would normally allow, plus a separate overload device sized close to running current, looks wrong to anyone used to ordinary branch circuits — and it is correct. Two devices, two jobs, which is the same theme as the two current values.
What this tool will not do
It contains no code tables. It does not know which edition your jurisdiction has adopted, what local amendments apply, or anything about your job, and it makes no determination of compliance. A licensed professional and the authority having jurisdiction decide that, and where they or the published code differ from the page, they are right.