Short answer: Part VII of Article 440 covers cord-and-plug-connected room air conditioners and similar units that are single-phase and rated 250 V or less (NEC 440.60). A unit by itself on a branch circuit can be up to 80 percent of the circuit rating. If the same circuit also feeds lighting outlets, general-use receptacles or other appliances, the unit is limited to 50 percent, unless the circuit is interlocked so the unit and the other outlets can’t be energized at the same time (NEC 440.62). The attachment plug and receptacle can serve as the disconnecting means when the manual controls on the unit are readily accessible and within 6 ft of the floor, or when an approved disconnect is installed within sight of the unit (NEC 440.63). The supply cord is generally no longer than 10 ft at 120 V and 6 ft at 208 V or 240 V (NEC 440.64), and single-phase cord-connected units have factory-installed leakage-current detection, arc-fault or heat detection protection (NEC 440.65).
PSI lists Equipment and Devices (10 scored NEC Knowledge and 2 scored Calculations questions) as a subject area of the Texas Journeyman exam, and names air conditioning, refrigeration and heating in it. PSI does not say how many questions cover room air conditioners. The Texas Journeyman Practice Pack includes 1,000 original questions and 10 timed mock exams in the real two-part format, plus step-by-step solutions for every calculation. You can try free practice questions with no sign-up. The full pack is US$39, paid once.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the rules in plain language and do not copy NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
Plug-in units have their own part
The HVAC and appliance circuits page covers hard-wired equipment: minimum circuit ampacity, maximum overcurrent protection from the nameplate, and appliance disconnects. A window or through-wall unit that plugs into a receptacle follows its own part of Article 440, and that part is what we cover here.
What counts as a room air conditioner (440.60)
Part VII applies to an air-cooled room air conditioner of the window, console or in-wall type, installed in the room it conditions, that has a hermetic refrigerant motor-compressor, is single-phase, and is rated 250 V or less. These units are permitted to be cord-and-plug-connected. Three-phase units and units rated over 250 V fall outside Part VII, so check the other parts of Article 440 for those.
Grounding (440.61). Room air conditioners are grounded under the rules for cord-and-plug-connected equipment, so the cord has an equipment grounding conductor and a grounding-type plug.
Branch-circuit limits (440.62)
Treated as a single motor unit. A room air conditioner is treated as a single motor unit when it is cord-and-plug-connected, rated not more than 40 A and 250 V single-phase, has its total rated-load current marked on the nameplate, and is on a circuit whose short-circuit and ground-fault protective device is rated no higher than the branch-circuit conductor ampacity or the receptacle rating, whichever is less.
| Circuit | Unit limit |
|---|---|
| Unit is the only load on the branch circuit | Marked rating not more than 80 percent of the branch-circuit rating |
| Branch circuit also supplies lighting outlets, general-use receptacles or other appliances | Total marked rating of the unit not more than 50 percent of the branch-circuit rating (80 percent if the circuit is interlocked so the unit and the other outlets can’t be energized at the same time) |
Disconnecting means (440.63)
For a single-phase room air conditioner rated 250 V or less, the plug and receptacle can serve as the disconnect if either of these is true:
- The manual controls on the unit are readily accessible and located within 6 ft of the floor.
- An approved manually operable disconnecting means is installed in a readily accessible location within sight of the unit.
If the controls are 7 ft above the floor, they miss the 6 ft condition. The plug can still serve as the disconnect once an approved disconnect is installed within sight of the unit.
Supply cord length (440.64)
| Nameplate voltage | Maximum cord length |
|---|---|
| 120 V | 10 ft |
| 208 V or 240 V | 6 ft |
Leakage-current and arc-fault protection (440.65)
Single-phase cord-and-plug-connected room air conditioners come with one of these from the factory:
- Leakage-current detector-interrupter (LCDI)
- Arc-fault circuit interrupter (AFCI)
- Heat detecting circuit interrupter (HDCI)
The device is factory-installed as part of the attachment plug, or located in the power supply cord within 12 in. of the plug. Adding a breaker at the panel doesn’t replace it.
Worked example: a window unit on an existing circuit
A 120 V window air conditioner has a nameplate rating of 12 A. The bedroom receptacle is on a 20 A branch circuit.
- Alone on the circuit: 80 percent of 20 A = 16 A. The 12 A unit passes the 80 percent limit.
- Same circuit also supplies the bedroom lights and other receptacles: 50 percent of 20 A = 10 A. A 12 A unit is too large, unless the circuit is interlocked as described above.
- Fix: give the 12 A unit its own 20 A circuit, or pick a unit rated 10 A or less for the shared circuit. Either way, check the receptacle rating and the unit’s instructions too.
- Cord: at 120 V, the cord can be up to 10 ft. Do not add an extension cord to reach a receptacle farther away.
Four quick questions
- A 15 A individual branch circuit. Largest room air conditioner rating allowed? 12 A (80 percent).
- A 20 A circuit that also supplies lights. Largest room air conditioner rating? 10 A (50 percent).
- Maximum cord length for a 240 V room air conditioner? 6 ft.
- Unit controls 5 ft above the floor and readily accessible. Can the plug serve as the disconnect? Yes.
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Put “80 / 50” in the margin at 440.62
NFPA 70, National Electrical Code, 2026 Edition (softcover). Write “80 alone, 50 shared” next to 440.62 and “10 ft at 120 V, 6 ft at 208/240 V” next to 440.64, so the two numbers are visible together. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
Does a window air conditioner need its own circuit?
Not always. Alone on a circuit, the unit can be up to 80 percent of the circuit rating. On a circuit that also supplies lights, general-use receptacles or other appliances, it is limited to 50 percent, or 80 percent with an interlock.
Can the plug be the disconnect for a window AC?
Yes, when the unit’s manual controls are readily accessible and within 6 ft of the floor, or when a disconnect is installed within sight.
How long can the cord on a room air conditioner be?
Up to 10 ft at 120 V and up to 6 ft at 208 V or 240 V.
What is the LCDI on an air conditioner cord?
A leakage-current detector-interrupter built into the plug, or into the cord within 12 in. of the plug. Room air conditioners have an LCDI, AFCI or heat detecting circuit interrupter installed by the manufacturer.
Does Part VII cover a three-phase unit?
No. Part VII covers single-phase cord-and-plug-connected units rated 250 V or less.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, Article 440
