Most homeowners obsess over BTUs.
“How many BTUs do I need?”
“Will 15,000 BTUs cool my room?”
“Should I size up just to be safe?”

Tony hears this every week. And while BTUs matter for comfort, electrical capacity is what decides whether the system actually runs — safely, reliably, and without burning the place down.

“A PTAC doesn’t run on BTUs. It runs on electricity.
Get the electrical wrong, and the BTUs won’t even turn on.” — Tony

Before you install a 15,000 BTU PTAC, the one Tony sees most often — like the Amana 15k PTAC here:
https://thefurnaceoutlet.com/products/amana-j-series-model-15-000-btu-ptac-unit-with-3-5-kw-electric-heat-ptc153j35axx —
you need to confirm three things:

• Voltage

• Amperage

• Wire gauge

Because a 15k PTAC isn’t a lightweight machine.
It’s basically a wall-mounted power plant.

This article breaks down Tony’s entire electrical checklist — the one he uses BEFORE he even lets someone order a PTAC — and explains why ignoring this stuff is what destroys compressors, trips breakers, melts wires, and sends entire hotels into “Why is half the building cold?” panic mode.

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⚡ Why Electrical Specs Matter More Than Cooling Capacity

You can have:

• the perfect cooling load

• the ideal BTU rating

• the best PTAC brand

• premium heat kit

• brand-new sleeve

…but if your electrical infrastructure can’t handle the actual amp draw, the entire system:

• fails early

• overheats

• trips constantly

• runs weak

• produces low CFM

• burns out contactors and relays

• damages heat strips

• stresses the compressor

Tony puts it like this:

“BTUs tell you what the room needs.
Voltage and amps tell you whether the equipment can survive.”

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🔌 Electrical Reality #1 — Voltage Isn’t Optional, It’s the Backbone

A 15,000 BTU PTAC almost always requires 230/240V power, not 115V.

Why?

Because:

• 115V can’t deliver enough wattage for both cooling AND heating

• Voltage drop is higher on 115V circuits

• 230V allows higher amp loads without overheating

• Electric heat kits (3.5 kW – 5 kW) NEED 230V

• Startup currents are too high on 115V

The U.S. Department of Energy breaks this down in their electrical heating guidance:
https://www.energy.gov/energysaver/electric-resistance-heating

Tony’s rule:

“If you’re buying a 15k PTAC, you’re running 230 volts. Period.”

Installing a 15k unit on the wrong voltage is the #1 cause of early compressor death Tony sees in DIY installs.

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🔌 Electrical Reality #2 — Amps Decide What Your Breaker Needs to Be

A typical 15k PTAC draws:

• Cooling: 6–9 amps

• Heating (3.5 kW kit): ~15–17 amps

• Heating (5 kW kit): ~21–23 amps

• Total circuit requirement: Usually 20A or 30A

If you pick the wrong amperage model, you:

• overload your circuit

• trip breakers

• melt wire insulation

• damage the heat kit

• reduce PTAC lifespan

This is why Amana, GE, Friedrich, and LG make multiple electrical versions of the exact same BTU PTAC.

And this is why Tony ALWAYS asks a customer:

**“Do you have a 20-amp or 30-amp circuit?

And what wire gauge is on it?”**

If you don’t know, you’re not ready to buy a PTAC.

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🧵 Electrical Reality #3 — Wire Gauge Matters MORE Than Breaker Size

This is the rule most homeowners (and many contractors) get wrong.

A 30-amp breaker means NOTHING
if the wire gauge is too small.

Tony has seen fires started because someone ran:

• 14-gauge wire on a 20A breaker

• 12-gauge wire on a 30A breaker

• 16-gauge extension cords to PTACs (which should NEVER exist)

The National Fire Protection Association (NFPA) specifies wire sizing safety requirements in the National Electrical Code:
https://www.nfpa.org

Here’s Tony’s quick reference chart:

Wire gauge protects:

• the walls

• the insulation

• the breaker

• the PTAC

• the people living in the room

You NEVER size wire based on load alone — you size wire based on ampacity, temperature rating, and continuous use.

Tony’s rule is non-negotiable:

“Breakers protect wires.
Wires protect equipment.
If your wire is wrong, your whole system is wrong.”

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🔥 The Heat Kit Changes EVERYTHING (Tony’s 3-Minute Explanation)

Cooling amps are nothing compared to HEATING amps.

A 15k PTAC with a heat pump might pull:

• 6–9 amps cooling

• 4–6 amps heating (heat pump only)

But add a 3.5 kW electric heat kit?

You just added 15 amps.

Add a 5 kW heat kit?

You just added 21+ amps.

This is why Tony always checks the HEAT kit amps before installation — not just cooling load.

Electric heat is brutal on wiring. It's pure resistance heating. The DOE breaks down resistance heating power draw here:
https://www.energy.gov/energysaver/electric-resistance-heating

Tony never installs a PTAC heat kit unless:

• the panel can support it

• the circuit is properly sized

• the wire gauge is correct

• the outlet and plug match the amperage

• the run length doesn’t exceed voltage-drop tolerances

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🪫 Voltage Drop — The Silent PTAC Killer

Voltage drop happens when:

• the wire run is too long

• the wire gauge is too small

• too many devices share the circuit

• connections are loose

• breakers are worn

The farther the voltage has to travel, the more it drops before reaching the PTAC.
When voltage drops, amperage spikes.
When amperage spikes, wires get hot.

Tony sees this weekly in older buildings with long wire runs.

Symptoms of voltage drop:

• PTAC sounds weak

• fan runs slow

• compressor struggles to start

• lights flicker when heat kicks in

• unit trips randomly

• heat kit overheats

• cooling capacity drops 20–30%

• you hear buzzing at outlets

• the unit runs hot to the touch

ASHRAE provides guidelines for ensuring electrical supply stability for HVAC equipment:
https://www.ashrae.org/technical-resources/ashrae-handbook

Tony’s solution?

He oversizes wire gauge by one step anytime a run exceeds:

• 50 feet on 20A

• 75 feet on 30A

Because bigger wire = less voltage drop.

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🔥 Here’s What Happens When You Ignore Wire, Voltage, and Amps

Tony has replaced too many PTACs that were installed electrically wrong.
Here are real consequences:

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🔥 1. Burned-Out Heat Kits

Heat kits short out fast when voltage drops or wire gauge is undersized.

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🧊 2. Weak Cooling & Low CFM

Low voltage = low motor torque = low airflow.
The PTAC can’t throw air far enough into the room.

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🚫 3. Breakers Trip Constantly

Breaker trips aren’t “annoying.”
They’re the breaker preventing a fire.

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⚡ 4. Melted Wires Behind the Wall

Overheating wire insulation can smolder for weeks before igniting.

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💨 5. Compressor Failure

Under-voltage causes the compressor to stall or run hot.
This kills it years early.

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🔥 6. “Hot Plug Syndrome”

This is Tony’s name for plugs that get too hot to touch.

Cause?
Loose connections + high amperage.

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💸 7. You Think the PTAC Is Bad… But It Was the Wiring All Along

Tony replaces “broken” PTACs that work perfectly…
once installed on the correct circuit.

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📐 Tony’s Electrical Checklist BEFORE Choosing a 15k PTAC

Tony never installs a 15k PTAC until he answers THESE questions:

1. What voltage is available? (115 vs 230/240)

If it’s 115V, STOP.
Upgrade or choose a smaller unit with no big heat kit.

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2. What size breaker is on the circuit?

• 20A? Use 12-gauge wire.

• 30A? Use 10-gauge wire.

• If it doesn’t match, fix the wiring.

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3. What OTHER devices are on the circuit?

A PTAC must be on a dedicated circuit.

Tony refuses installs where the PTAC shares power with:

• mini-fridges

• microwaves

• TVs

• outlets

• lighting

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4. What is the TOTAL amp draw with the heat kit?

Tony calculates this BEFORE ordering the unit.

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5. What gauge wire is in the wall RIGHT NOW?

He checks the actual wire.
Never trusts breaker labels.
Never trusts the homeowner’s memory.

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6. How long is the wire run?

Longer runs → thicker wire.
Tony refuses to accept voltage drop.

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7. Does the outlet match the PTAC plug type?

Different amperage PTACs use different plug shapes.
Wrong outlet = no-go.

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8. Is the panel capable of supporting the load?

Sometimes the panel is already maxed out.
Then Tony gives the customer TWO choices:

• downsize the PTAC

• upgrade the panel

No exceptions.

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🛠️ Real-World Scenarios (Tony’s Fixes)

🏨 Hotel Room: 15k PTAC kept tripping at night

Cause:
12-gauge wire on a 30A circuit.

Fix:
Replace branch circuit with 10-gauge.

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🏠 Apartment: Heat kit burned out in 6 months

Cause:
Low voltage from long wire run.

Fix:
Oversize wire gauge + new dedicated circuit.

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🏬 Office: PTAC cooling weak on hot afternoons

Cause:
Voltage drop when office equipment surged.

Fix:
Separate circuits + tighten panel connections.

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🧊 Basement: PTAC fan weak, compressor overheating

Cause:
115V on a long run, voltage fell to 108V.

Fix:
Convert circuit to 230V and shorten run.

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🧠 Tony’s Golden Rule of PTAC Electrical Design

“The electrical system MUST be sized for the heater, not the air conditioner.”

Cooling amperage is the smallest part of the equation.

Electric heat is the monster.
And a 15k PTAC with a 5 kW heat kit is a BEAST electrically.

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🏁 Final Word — BTUs Don’t Matter If the Power Supply Can’t Feed Them

Tony respects BTUs.
But he respects electricity more.

Because BTUs are math…
Electricity is safety.

If you choose a PTAC based only on BTUs, you risk:

• overheating

• breaker trips

• weak cooling

• fire hazards

• burned heat kits

• premature compressor failure

But if you size:

• voltage

• amps

• wire gauge

• heat kit load

• circuit capacity

• outlet type

correctly, your PTAC will:

• run quieter

• cool stronger

• heat faster

• last longer

• cost less to operate

• stay safe

Tony’s final say:

“If the wire isn’t right, the PTAC isn’t right.
BTUs don’t matter if the power can’t get there.”

Buy this on Amazon at: https://amzn.to/47cH9ut

In the next topic we will know more about: Your Return Air Is the Real Thermostat — Fix That and Your System Behaves - Tony’s airflow-first plan for PTAC installs that never short cycle or freeze