Low-Voltage DC Drop
DC voltage drop and percent at 12 / 24 / 48 V with application-tolerance flags.
Example
You enter
- System voltage 12
- AWG 10
- Run length one-way (ft) 20
- Current (A) 10
- Application led_lighting
You get
- Drop 0.407 V
- Percent 3.39 %
- Status exceeds tolerance
Details, formula, and sources
VD = 2 × I × R × L for 12 / 24 / 48 V DC systems with copper resistance per NEC Chapter 9 Table 8.
NEC 2023 (NFPA 70). Chapter 9 Table 8 (used as a copper-resistance reference, not as a low-voltage code).
Free read-only access at nfpa.org/freeaccess.
Estimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
Field names used by the API: system_V, awg, run_length_ft, current_A, application, drop_V, percent, acceptable
- Application tolerance LED 3% / marine 10% / RV 5% / audio 2%engineering practice by application