Class 2 Voltage Drop Calculator (24V)
How do I calculate voltage drop on a 24V thermostat wire?
This calculator uses the NEC Chapter 9 Table 8 K-method on a 2-wire loop: Vd = 2 × K × I × L / circular mils, where L is the one-way length. For an 18 AWG copper run it pulls K and the 1,620 circular-mil area, computes the volts dropped, and divides by your supply voltage for percent drop. It then flags whether the result stays within your device tolerance.
Run the numbers for your project
Use the Class 2 Voltage Drop Calculator (24V) to get an exact answer for your inputs.
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