What does this motor's complete circuit look like?
Pick the motor and get the full NEC Article 430 branch circuit, drawn as a one-line — tap any element to see the code path.
Result
- Overload
- ≤ 17.5 A
- Disconnect
- 30 A
- Ground
- 10 AWG
- Conduit
- 1/2″ EMT
Motor — where every number starts
Table 430.250: a 10 HP three-phase motor on the 460 V column draws 14 A full-load. Circuit sizing uses this table value — not the nameplate — by 430.6(A). The nameplate current has exactly one job here: setting the overload.
How is this calculated?
Using the tool
Pick the motor and the designer builds the whole NEC Article 430 branch circuit live — conductors, breaker, overload, disconnect, ground, and conduit — drawn as a one-line. Tap any element in the diagram to see the code path behind its number.
The code
A motor branch circuit is five sizing decisions, each from its own NEC rule, all keyed to the full-load current in Table 430.250 (never the nameplate, except the overload — 430.6(A)): conductors at 125% of FLA on the 75°C column (430.22), checked for ≤3% voltage drop over the actual run; an inverse-time breaker up to 250% of FLA, next standard size allowed (430.52); the overload at 125% — or 115% without service-factor headroom — of nameplate (430.32); a disconnect at 115% of FLA within sight of the motor (430.110); and the equipment ground from 250.122, keyed to the breaker.
The idea that makes motor circuits different: protection is split. The breaker only clears short circuits and lets the starting inrush through; the overload protects the motor and the wire from sustained overcurrent. That split is why a 35 A breaker on a 20 A wire is code-legal here (240.4(G)) and nowhere else in the panel.
New to the math? Learn the concept: Motor circuits