Motor Locked-Rotor Current from Code Letter (NEC 430.7(B))
Starting current from the nameplate code letter, not '6x FLA': NEC Table 430.7(B) maps the code letter (A-V) to a locked-rotor kVA/hp band, and locked_rotor_kva = hp x kVA/hp, LRA = kVA x 1000 / (sqrt(3) x V). A 25 hp code-G 460 V motor tops out at 6.29 kVA/hp -> 157 kVA -> 197 A (5.8x its 34 A FLA, so the rule of thumb fits); the same motor as code J (7.99 kVA/hp) draws 251 A -> 7.4x FLA, and an instantaneous-trip breaker or voltage-dip check sized on '6x' would be undersized. The code letter is about starting kVA and is NOT the design letter (A/B/C/D) for the torque-speed curve. A design aid; the nameplate and measured inrush govern.
Formula and source
kVA/hp = upper bound of the Table 430.7(B) code-letter band; locked_rotor_kva = hp x kVA/hp; LRA = kVA x 1000 / (sqrt(3) x V) three-phase, kVA x 1000 / V single-phase.
The NEC 2023 Table 430.7(B) locked-rotor indicating code letters, mapping the nameplate code letter to a locked-rotor kVA/hp band, by name; the motor nameplate and measured inrush govern.
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