WireGaugeCalc Free calculator · NEC cited · works offline
Heat Pump Voltage Drop 240
Heat pump voltage drop 240 is quick with WireGaugeCalc, since the tool runs the drop from your load amps, run length, and wire size on a 240 volt circuit.
You enter the one-way distance and conductor, so the calculator returns the percent drop at the unit.
That tells you if the run stays inside the 3% branch-circuit guideline before you pull wire.
Open the calculatorUses Vd = (phase factor × K × I × L) / circular mils, K = 12.9 copper, 21.2 aluminum. Field aid only, verify against the current NEC and your local authority having jurisdiction.
How the 240 volt heat pump drop is figured
Voltage drop rises with distance and current, so a long run to a heat pump can fall below the voltage the compressor needs to start.
The NEC keeps branch-circuit voltage drop near 3% as a guideline, so the tool flags runs that pass it.
Copper and aluminum read differently, since aluminum has higher resistance per size.
What drives the drop on a 240 volt heat pump run
WireGaugeCalc weighs the inputs behind heat pump voltage drop on a 240 volt circuit:
- One-way run length to the condenser
- Heat pump load amps from the nameplate MCA
- Copper versus aluminum conductor
- Wire gauge from 10 AWG up
- The 3% branch-circuit voltage drop guideline
- 240 volt single-phase reference
One app for every NEC calculation
WireGaugeCalc keeps the calculations you reach for most in one place:
- Voltage drop and wire sizing for any run
- Conduit fill for EMT, PVC, and RMC
- Box fill and junction box sizing
- Ampacity and temperature derating
- Motor circuit and load calculations
- Conduit bend offsets and saddles
Built for the field, works offline
The whole app runs on your phone, so it keeps working in a basement, an attic, or a job site with no signal.
There is no account to create and nothing to load. Open it, run the number, and get back to work.
- No signup and no signal needed
- Answers in a tap, not a spreadsheet
- Same tool on phone, tablet, and desktop
Every result cites the NEC article
Each answer shows the table or formula it came from, so you can check the method and learn the code as you go.
That makes the app useful on the job and during exam prep, since the reasoning is right next to the number.
Switch the code year your job runs on
Jurisdictions adopt the NEC at different times, so you can match the calculation to the code in force:
- NEC 2017, 2020, and 2023 tables
- Copper and aluminum conductors
- 60, 75, and 90 degree C terminations
- Single-phase and three-phase systems
Run the number, then get back to work
Stop flipping through a paper book or hopping between calculator sites. Enter your values, read the code-cited answer, and move on. Free to use, no signup.
Open the calculatorFrequently asked questions
What voltage drop is acceptable for a 240 volt heat pump?
The NEC recommends keeping branch-circuit voltage drop at or below 3 percent, which protects compressor starting. Treat this as a guideline and confirm any local requirement with your authority having jurisdiction.
Should I use MCA or running amps for the heat pump drop?
Size the conductor from the nameplate minimum circuit ampacity, then check voltage drop at the running load for a realistic figure. The tool accepts the amps you enter, so use the value that matches your purpose.
Is WireGaugeCalc free to use?
Yes. Every calculator is free to run with no signup. A paid tier adds saved projects, PDF reports, and extra code years, but the core math stays free.
Does it work without internet?
Yes. The app runs on your device, so it keeps working with no signal on a job site, in a basement, or in an attic.
Are the results code accurate?
Results follow published NEC tables and standard formulas, and each answer shows the article it came from. It is a field aid, not a stamp of approval, so verify against the current code and your local authority before you wire anything.
Which NEC code year does it use?
You can switch between NEC 2017, 2020, and 2023, since jurisdictions adopt the code at different times. Pick the year your job runs on.