HVAC circuits on a Texas paper, where a national answer and a Texas answer come apart

What the exam asks about HVAC

Air conditioning and heating equipment reaches the exam from three directions at once. In our 500 question bank, seven questions mention air conditioning and six of those sit in the load calculation area, where the equipment appears as a number in a dwelling total. One question asks which article governs a sealed compressor. One question asks what a Texas candidate should do with an exception the national code retires. Another covers the limit on a cord connected room air conditioner sharing a circuit.

So the topic tests three different skills. Load calculation questions want the noncoincident rule and the demand factors. Equipment questions want Article 440 and its two marked currents. The Texas adoption question wants you to know that the book in your hands was amended before it got to you.

Where Texas and the national text disagree

This is the clearest conflict between two official documents anywhere on a Texas paper, and it is worth setting out in full because both sides are correct about their own jurisdiction.

The national text. NEC 210.8(F) covers outdoor outlets at dwellings and carries an exception for listed heating, ventilation and air conditioning equipment. Printed inside that exception is a sentence saying it expires on 1 September 2026.

The Texas adoption. 16 TAC 73.100(b) adopts that exception with the expiration sentence left out. A state adoption is free to amend what it adopts, and this one did. So on 2 September 2026 the exemption in Texas is doing exactly what it did on 31 August.

A proposal to move the national date back is pending at NFPA and nothing about it has been decided, which is a different situation from the amendment Texas has already made.

The third exception, which most summaries skip

Relief stays available in other states anyway, because the 2026 edition added a third exception to 210.8(F) and it carries no expiry at all. It permits a listed Class C special purpose ground-fault circuit interrupter on listed HVAC equipment, and where one is fitted the disconnect serving that equipment carries a warning label stating that Class C protection is provided for the unit.

A Class C device is a different animal from the Class A GFCI in a bathroom. It is a listed special purpose device for circuits with no conductor over 300 volts to ground, used where reliable equipment grounding or double insulation is provided, and it passes more leakage current before opening than a Class A device does. An informational note alongside it points at special purpose devices marked HF, built for the high-frequency leakage current that inverters and variable speed drives put on a circuit.

Texas adopted the rest of the subsection as written, so the Class C route is open here as well. One more figure moved in the same subsection this cycle: the ceiling on the branch circuits it reaches went from 50 amperes to 60.

Why Article 430 does not fit this equipment

The compressor in a condensing unit or a heat pump is sealed in one housing with its motor, so there is no shaft coming out of it and no horsepower on the plate. That is what a hermetic refrigerant motor compressor means.

The ordinary motor method begins by looking a horsepower up in a full-load current table, and with nothing to look up it has no starting point. Article 440 works from what the manufacturer measured, which arrives on the nameplate as a current in amperes. The article modifies Article 430 and says which of the general motor requirements still apply, so a question about a rooftop unit can send you to two articles, and answering out of the motor article alone produces a confident wrong number.

The wording of the stem is the tell. Hermetic, compressor, condensing unit, rated-load current and branch-circuit selection current all point at Article 440. Horsepower, service factor and a table lookup point at Article 430. Fixed electric space heating in the same cabinet belongs to Article 424, and an appliance with a motor in it belongs to Article 422.

What the nameplate hands you

Article 440 works from two currents printed on the nameplate.

Rated-load current is what the compressor draws running at its rated load, voltage and frequency, and it is the base figure the article works from. Branch-circuit selection current appears on some equipment and stays absent on others. Where it is printed, it takes the place of the rated-load current when you size conductors, the disconnect, the controller and the protective device, and it is always the larger of the two.

That is why the sizing rules in Article 440 keep saying whichever is greater. A nameplate printing both figures is handing you a decision, and a question printing both is checking whether you noticed the second one.

The two marked numbers

Packaged equipment arrives with a minimum circuit ampacity and a maximum overcurrent protective device rating marked on it. Between them they are the manufacturer handing you the result of a calculation you would otherwise build yourself.

Where a nameplate gives no maximum, the branch-circuit short-circuit and ground-fault rules in Article 440 do the work. They take you to 175 percent of whichever of the two currents is greater, and permit a move up toward 225 percent only where the equipment will not start on the lower figure. Where a nameplate does give a maximum, that marking governs wherever it sits below what the percentages would allow, and on packaged equipment it usually does.

The habit that costs the point comes from the motor branch circuit, where you calculate a device rating and round up to the next standard size. Here the printed maximum is the end of the road, and the rounded-up answer will be among the options.

Cord connected room air conditioners

Article 440 carries a part written for cord connected room air conditioners, which treats the unit as a single motor load. The marked rating is held to 80 percent of the branch circuit rating where the circuit supplies nothing else, and to 50 percent where lighting units or other appliances share it.

The reason is starting current arriving on a circuit that is already carrying load, and the 50 percent figure is the one candidates skip. On a 20 ampere circuit shared with the room lighting, the unit's rated current stays at or below 10 amperes.

Where HVAC enters a load calculation

Six of the seven air conditioning questions in our bank sit in the load calculation area. Heating and air conditioning are noncoincident loads, and the calculation carries the larger of the two. Adding them together is the most common error on dwelling calculations.

Two refinements generate the harder questions. An air handler blower that runs whenever either system operates belongs in both groups when you compare them, and gets counted once in the answer. And the standard method and the optional method can select different winners for the same house, because the optional method discounts the heating enough that the air conditioning can come out ahead. One bank question walks the same dwelling through both and lands on the heating under one method and the cooling under the other.

Air conditioning equipment also sits outside the appliance demand factor. The rule counts appliances fastened in place other than ranges, clothes dryers, space heating equipment and air conditioning equipment, because each of those four already has a demand rule of its own elsewhere. The load calculation area covers the rest of that sequence.

The disconnect, and the receptacle beside it

NEC 440.14 puts the disconnecting means within sight from the equipment and readily accessible from it. Those are two separate requirements and a question will usually test the second, because the first is the one everybody remembers. It may sit on or within the equipment itself. It is barred from a panel that has to come off to reach the equipment, and from any position that would obscure the nameplate.

Within sight is a defined term in Article 100 with a distance inside it, and readily accessible is a second defined term about what stands between a technician and the handle. Look both up.

NEC 440.15 is new this edition, and small new sections get written into questions early. On a split system in other than a one- or two-family dwelling, the outdoor disconnecting means is marked with the location of the indoor units it feeds.

NEC 210.63 puts a servicing receptacle outlet near heating, air conditioning and refrigeration equipment so a technician has somewhere to plug in, and the section states the distance and the location. Where that equipment sits outdoors at a dwelling, the servicing outlet is an ordinary general use receptacle in an outdoor location, so the listed equipment exception has nothing to say about it. Two outlets four feet apart on the same wall can be answered differently because one serves the listed equipment and one is there for a person with a drill.

What to do before test day

Article 440 is short and most candidates have never opened it, which makes twenty minutes with it one of the better returns available. Tab it at the disconnecting means part and at the branch circuit rules, and mark 440.15 while the book is open.

Put a second tab on 210.8(F) and write 16 TAC 73.100(b) beside it. Read all three exceptions under that subsection while you are there, because the third answers a question the second cannot reach. Then check that whatever update material you are using names the 2026 edition, since Texas examinations reference it from 1 September 2026.

For the sizing worked through with figures on the page, the question sets carries the HVAC circuits page, which is where the worked arithmetic lives. Then run the thirty free questions timed. If a stem describes a rooftop unit and offers you a feeder sum, check the packaged equipment rule before you start adding motors, because 430.25 takes that calculation off your hands.

Questions people ask

Did the GFCI exception for outdoor HVAC equipment expire in Texas?

No. The national text at NEC 210.8(F) carries an exception for listed heating, ventilation and air conditioning equipment with an expiration date of 1 September 2026 printed inside it. Texas adopted that exception at 16 TAC 73.100(b) with the expiration sentence removed, so the exemption has no expiry here. A proposal to move the national date has been filed with NFPA and nothing about it is settled, which is separate from what Texas has already done. National courses and national trade writing will tell you this lapsed, and in Texas it did not.

What is a Class C SPGFCI and when does it apply?

It is a listed special purpose ground-fault circuit interrupter, permitted by the third exception added to NEC 210.8(F) in the 2026 edition, and that exception carries no expiry anywhere. It suits circuits with no conductor over 300 volts to ground where reliable equipment grounding or double insulation is provided, and it passes more leakage current before opening than the Class A device in a bathroom receptacle. Where one is fitted on listed HVAC equipment, the disconnect serving that equipment carries a warning label saying Class C protection is provided for the unit.

Why does a rooftop unit use Article 440 and not Article 430?

Because the compressor is hermetic. It runs sealed in one housing with its motor, so there is no shaft and no horsepower marking, and the general motor method has no horsepower to carry into a full-load current table. Article 440 works from the rated-load current and the branch-circuit selection current printed on the nameplate. It modifies Article 430 and states which general motor requirements still apply, so a question about this equipment can reach two articles at once and the stem wording tells you where to start.

Which way do the minimum circuit ampacity and the maximum device rating round?

In opposite directions, and reversing them is the common miss. The minimum circuit ampacity is a floor, so the conductor is selected at or above it after your own ambient and bundling corrections and the termination temperature check. The maximum overcurrent protective device rating is a ceiling, so you take the largest standard device at or below the marking. The motor branch circuit habit of rounding a calculated device rating up to the next standard size produces an answer that will be sitting among the options here.

How are heating and air conditioning handled in a dwelling load calculation?

As noncoincident loads, so the calculation carries the larger and leaves the smaller out. Adding both is the most common error on dwelling calculations and no demand factor rescues it. An air handler blower that runs with either system belongs in both groups while you compare them and gets counted once in the result. The standard method and the optional method can pick different winners for the same house, because the optional method discounts the heating enough that the air conditioning at full value can come out ahead.

What limits a room air conditioner plugged into a shared circuit?

Fifty percent of the branch circuit rating. Article 440 carries a part for cord connected room air conditioners that treats the unit as a single motor load, and it holds the marked rating to 80 percent of the branch circuit rating where the circuit supplies nothing else, dropping to 50 percent where lighting units or other appliances share it. The reason is starting current arriving on a circuit already carrying load. On a 20 ampere circuit shared with room lighting, that puts the unit at or below 10 amperes.