NEC 440 — Air-Conditioning Equipment: Disconnects, Conductor Sizing, and the Maximum Overcurrent Rating

NEC 440 covers air-conditioning and refrigerating equipment — split-system condensers, heat pumps, mini-splits, and similar hermetic-motor-compressor equipment. Different from general motor rules because A/C equipment has its branch-circuit sizing pre-calculated by the manufacturer and printed on the nameplate.

Read the nameplate, not the table. Every A/C condenser and heat pump unit is labeled with two key numbers:

• MCA — Minimum Circuit Ampacity: the minimum conductor ampacity required. Size your conductors to this number.
• MOP — Maximum Overcurrent Protection: the maximum breaker or fuse rating allowed. Size your breaker to this number or smaller (next standard size down).

Example: a Carrier 3-ton heat pump nameplate shows MCA 22 A, MOP 35 A. Branch circuit:

• Conductors: 22 A → #10 CU THHN/THWN-2 minimum (30 A capacity)
• Breaker: 35 A maximum, but standard sizing → 30 A (or 35 A if you have it)

You ignore the regular 125% motor multiplier on A/C — the manufacturer already applied it when calculating MCA.

Condenser disconnect (440.14): every air-conditioning condenser unit needs a disconnect WITHIN SIGHT of the condenser. "Within sight" per NEC 100 means visible AND not more than 50 ft away. For typical residential outdoor condenser installs, this means a NEMA 3R-rated outdoor disconnect mounted on the wall next to the condenser.

The disconnect can be:

• Non-fused safety switch (most common for residential, ~$30 at supply houses)
• Pull-out fuse disconnect (slightly more, allows local fusing)
• Listed lockable circuit breaker at the panel (only if the panel is within sight of the condenser — rare on outdoor installs)

GFCI required at outdoor A/C disconnect (210.8(F) — added in 2020 NEC, NJ adopted Sept 2026): all outdoor 125V/250V receptacle AND OUTLETS within 50 ft of the dwelling now require GFCI protection. The 2023 NEC explicitly extends this to A/C disconnects, even when hardwired. Big change for NJ permit reviews on heat-pump installs going forward.

Mini-split outdoor condenser disconnect: same rule applies. The condenser unit needs a disconnect in sight. Whip from disconnect to unit is typically LFMC (liquidtight flexible metal conduit) for the last 3-4 ft to absorb vibration.

Heat pump WITH strip heat backup: NEC 220.82(C) treats this as the LARGER of A/C or HEAT for load calc purposes, BUT the manufacturer's installation manual may specify a combined-mode load (compressor + strips) during defrost. Always check the manufacturer's load specifications before quoting service-upgrade work.

For HVAC load calc, the free Malfettone Load Calculator at /tools/load-calculator has central A/C, heat pump, mini-split, and electric furnace presets that apply the larger-of-A/C-or-heat rule.