Motor Disconnect Rules Chart
The NEC rules that govern motor and HVAC disconnects, in one matrix: how big the disconnect must be (the 115% rule and its HP-rated exception), the seven device types allowed to serve, the small-motor and cord-and-plug shortcuts, the within-sight geometry and its lockable-disconnect exceptions, and the Article 440 variants for air-conditioning equipment. Each row cites its section — the adopted edition and local amendments in your jurisdiction govern.
Disconnect rules, NEC Article 430 Part IX + Article 440
| Topic | Rule | Cite |
|---|---|---|
| Minimum ampere rating | The disconnect for a motor circuit ≤1000 V must be rated at least 115% of the table full-load current (430.248/430.250). Exception: a listed unfused motor-circuit switch with an HP rating at least the motor’s may rate below 115%. | 430.110(A) |
| What qualifies as the disconnect | One of seven listed types: a motor-circuit switch rated in horsepower, a molded-case circuit breaker, a molded-case switch, an instantaneous-trip breaker that is part of a listed combination controller, a self-protected combination controller, a manual motor controller marked "Suitable as Motor Disconnect," or system isolation equipment. | 430.109(A)(1)–(7) |
| Stationary motors ≤ 1/8 HP | The branch-circuit overcurrent device may serve as the disconnecting means — no separate switch required. | 430.109(B) |
| Stationary motors ≤ 2 HP, ≤ 300 V | A general-use switch rated at least TWICE the motor full-load current qualifies; on AC circuits, an AC-only (not AC-DC) general-use snap switch qualifies where the motor FLC is no more than 80% of the switch’s ampere rating. | 430.109(C) |
| Large motors — isolating switch | Motors over 100 HP (AC) or 40 HP (DC) may use a general-use or isolating switch plainly marked "Do not operate under load." | 430.109(E) |
| Cord-and-plug motors | A horsepower-rated attachment plug and receptacle (or flanged inlet/cord connector) rated at least the motor rating can be the disconnect. The HP rating is not required for portable motors of 1/3 HP or less, or for appliances and room A/C covered by 422.33 / 440.63. | 430.109(F) |
| Torque motors | A general-use switch is permitted as the disconnect; the 115% sizing runs on nameplate current per 430.110(B). | 430.109(G) |
| In sight from the controller | Each motor controller needs an individual disconnecting means in sight from the controller location. | 430.102(A) |
| In sight from the motor | A disconnect must also be in sight from the motor and its driven machinery. The controller disconnect can serve if it is in sight from the motor — otherwise a lockable (per 110.25) out-of-sight disconnect is allowed only where an in-sight one is impracticable or adds hazard, or in industrial plants with written safety procedures and qualified-person servicing. | 430.102(B) + Exc. |
| What "in sight" means | Visible and not more than 50 ft (15 m) away, with an unobstructed line of sight — a wall breaks it. | Art. 100 (2017–2023) |
| Readily accessible | At least one of the two — the controller disconnect or the motor disconnect — must be readily accessible. | 430.107 |
| HVAC: rating | A/C and refrigeration disconnects are sized at 115% of the nameplate rated-load current OR the branch-circuit selection current, whichever is GREATER; combination loads use 115% of the summed currents. | 440.12 |
| HVAC: location | Within sight from and readily accessible from the equipment; mounting on or within the unit is fine, but never on access panels or covering the nameplate. The 2023 edition adds 110.26(A) working-space compliance. | 440.14 |
How the pieces fit
Work the disconnect question in three passes. First the rating: 115% of table FLC — pull it from the motor FLA chart — then round up to a standard switch size from the safety switch ratings chart. Second the device: a horsepower-rated safety switch is the workhorse answer, but a molded-case breaker in the panel qualifies too. Third the geometry: one disconnect in sight of the controller, one in sight of the motor, one device wearing both hats whenever the layout allows.
The lockout exception trips people up in both directions. A lockable breaker does NOT erase the in-sight-of-motor rule on ordinary jobs — the exception is reserved for locations where a local switch is impracticable or adds hazard, and for industrial plants with written safety procedures and qualified-only maintenance. If the job is a strip-mall rooftop unit, run the local disconnect.
Common questions
How do I size a motor disconnect?
Rate it at least 115% of the motor full-load current from the NEC tables (430.248 single-phase, 430.250 three-phase) — table current, not nameplate. A 25 HP, 460 V motor draws 34 A from the table, so the disconnect must be rated at least 39.1 A: a 60 A safety switch is the standard pick. An HP-rated switch matching the motor HP also qualifies without the 115% math.
Does every motor need its own disconnect switch?
Every controller needs a disconnect in sight of it, and every motor needs one in sight of the motor — but one device can do both jobs when the controller disconnect is visible from the motor and within 50 feet. The separate local switch at the machine becomes mandatory when the panel is out of sight, unless a lockable-disconnect exception applies (impracticable location, or an industrial plant with written safety procedures).
What does "within sight" actually mean in the NEC?
Visible AND not more than 50 feet (15 m) away. Both halves matter: a switch 40 feet away behind a wall fails, and a visible switch 60 feet down the line fails. Through the 2023 edition the definition lives in Article 100; the 2026 edition relocates it to 110.29.
Can a breaker be the motor disconnect?
Yes — a listed molded-case circuit breaker is one of the seven permitted types in 430.109(A), and it needs no 115% check because breakers qualify by their ampere rating directly. The instantaneous-trip breaker inside a listed combination starter also counts, as does a manual motor controller marked "Suitable as Motor Disconnect."
What are the disconnect rules for air conditioners and heat pumps?
Article 440 tightens Article 430: the disconnect is sized at 115% of the nameplate rated-load current or the branch-circuit selection current, whichever is greater, and it must be within sight of AND readily accessible from the equipment — the reason every condenser has a pull-out disconnect on the wall beside it. Mounting on the unit is allowed, but never on an access panel or over the nameplate.
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