12.2 HVAC and Refrigeration Disconnects

Why This Matters for the TX Journeyman Exam

HVAC and refrigeration disconnects are a high-frequency exam topic in the NEC Knowledge part. Texas residential and commercial work is dominated by condenser and air-handler installations, and TDLR examiners test Article 440 Part IV relentlessly. The three rules that fail candidates most often are 440.13 (all ungrounded conductors), 440.14 (location), and 440.15 (rating). Learn them as a triad.

Article 440 Part IV — The HVAC Disconnect Triad

NEC 440.13 — What It Must Disconnect

A motor-compressor disconnecting means shall disconnect all ungrounded conductors to the motor-compressor and to any associated control or protective devices. A single-pole disconnect on a 240 V single-phase condenser is acceptable (two ungrounded conductors broken by a 2-pole device); a 3-pole disconnect is required for 3-phase equipment. A disconnect that leaves one ungrounded conductor energized violates 440.13.

NEC 440.14 — Where It Must Be

The disconnecting means shall be readily accessible and within sight of the motor-compressor and the equipment. The disconnect is permitted to be installed on or within the air-conditioning or refrigerating equipment, subject to three conditions:

Exceptions to the within-sight / readily-accessible requirement:

• Exception 1 — Supervised installations having written safety procedures that permit only qualified persons to service the equipment, and where the disconnect is located within sight of the equipment.
• Exception 2 — Where a plug-and-receptacle serves as the disconnecting means per 440.13.

The 'permitted on or within the equipment' rule is the one candidates get backwards. A factory- or field-mounted disconnect on the side of the condenser cabinet is code-compliant under 440.14, provided it is not on an access panel, does not obscure the nameplate, and leaves the 110.26(A) working clearance intact. The 'lockable disconnect not in sight' exception belongs to the 430.102(B) motor rule (Chapter 11), not to 440.14 — do not cite it for HVAC.

NEC 440.15 — Rating of the Disconnect

The disconnecting means shall have an ampere rating not less than 115% of the motor-compressor rated-load current (RLA) or the branch-circuit selection current, whichever is greater.

Minimum disconnect rating = RLA × 1.15

The result is compared to the standard ampere ratings in NEC 240.6(A): 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200 A … (note: 25 A and 35 A are standard ratings). Select the next standard rating at or above the calculated minimum.

Room Air Conditioners — 440.62 and 440.63

NEC 440.62 permits a room air conditioner to be connected to a branch circuit supplying other loads (lighting, receptacles) provided the total locked-rotor current of the A/C plus other loads does not exceed the branch-circuit overcurrent device rating, or to a dedicated branch circuit.

NEC 440.63 permits a cord-and-plug connection to serve as the disconnecting means for a room air conditioner when rated ≤ 250 V and ≤ 40 A. This is the window-unit rule — a 240 V, 20 A window A/C on a cord-and-plug connection satisfies the disconnect requirement without a separate disconnect switch.

Fixed Electric Space Heating — 424.19

NEC 424.19 requires a disconnecting means for fixed electric space-heating equipment. Where the equipment is not in sight of the disconnect, the disconnect shall be capable of being locked in the open (OFF) position (the lockable-remote pattern lives in 424.19, not 440.14). A separate disconnect is not required where the heater is cord-and-plug connected (a listed plug is the disconnect) or where a motor controller with a listed disconnect serves the equipment.

Worked Example: 3-Ton AC Condenser Disconnect

A 3-ton residential split-system condenser has a nameplate RLA = 20.5 A on a 240 V single-phase circuit. Where must the disconnect be, and what is the minimum rating?

Step 1 — Location (440.14)

The disconnect shall be:

• Readily accessible (not behind the condenser, not requiring a ladder to reach).
• Within sight of the condenser (visible and ≤ 50 ft).
• Permitted on or within the condenser enclosure, provided it is not on an access panel, does not obscure the nameplate, and meets 110.26(A) working clearances.
• A separate wall- or pad-mounted weatherproof pullout next to the condenser is also compliant and is the most common installation.

Step 2 — Rating (440.15)

Minimum rating = RLA × 1.15 = 20.5 A × 1.15 = 23.575 A ≈ 23.6 A

Step 3 — Select the Standard Rating (240.6(A))

The next standard ampere rating at or above 23.6 A is 25 A (25 A is a standard rating per 240.6(A)). A 25 A non-fused pullout disconnect satisfies 440.15. In practice, the smallest commonly stocked HVAC pullout is 30 A, and a 30 A disconnect also satisfies the rule — but 25 A is the code minimum.

Step 4 — Disconnect All Ungrounded Conductors (440.13)

A 240 V single-phase condenser has two ungrounded conductors; the disconnect shall be 2-pole to break both. A single-pole disconnect violates 440.13.

Answer: Install a 2-pole, 25 A minimum (30 A typical) weatherproof disconnect within sight of the condenser, readily accessible, breaking both ungrounded conductors. Mounting the disconnect on the condenser cabinet is permitted under 440.14 provided it is not on an access panel, does not obscure the nameplate, and 110.26(A) working clearances are maintained; a separate wall-mounted pullout is the common alternative.

Common Exam Traps

• 'On the equipment' is permitted. 440.14 permits mounting the disconnect on or within the equipment, subject to the access-panel, nameplate, and 110.26(A) restrictions. The older 'not on the equipment' wording was rewritten — do not answer from memory of the old text.
• 115%, not 125%. Motor FLC uses 125% for conductor sizing (430.22); the motor-compressor disconnect rating uses 115% (440.15). Don't cross the multipliers.
• 25 A is standard. Per 240.6(A), 25 A is a standard ampere rating — do not skip from 20 A to 30 A on a 440.15 calculation.
• Cord-and-plug as disconnect is limited to room A/C ≤ 250 V and ≤ 40 A (440.63). It does not apply to a permanent split-system condenser.
• Lockable-not-in-sight is a 430.102(B) motor rule, not a 440.14 rule. The 440.14 exceptions are supervised installations (Exc. 1) and plug-and-receptacle per 440.13 (Exc. 2).