Engineer Tool · NEC Article 700
Load & Voltage-Drop Calculator
Per-circuit emergency-load aggregation + DC voltage-drop check against the 5% industry ceiling. Uses copper resistance from NEC Chapter 9, Table 8. Recommends wire upsize when a circuit fails. Auto-sizes the Sage central battery.
Central battery bus
System Summary
144 W
Total load
6.0 A
Total current @ 24V
180 W
Sized (+25%)
Keystone
Recommended
⚠ 2 circuit(s) exceed the ceiling — see upsize recommendations below
Per-circuit analysis
| Circuit | W | A | Run | AWG | VD | VD % | Pass |
|---|---|---|---|---|---|---|---|
Circuit 1 10 × 8W | 80 | 3.33 | 150′ | 12 AWG → try 8 AWG | 1.93V | 8.04% / 5% | ✗ |
Circuit 2 8 × 8W | 64 | 2.67 | 220′ | 12 AWG → try 8 AWG | 2.26V | 9.44% / 5% | ✗ |
Engineering notes
- 2 circuits exceed the 5% voltage-drop ceiling. Upsize recommendations shown per circuit.
- Resistance values from NEC Chapter 9, Table 8 (copper, uncoated, DC, 75°C).
- NEC 700.26: "Emergency system wiring shall not be mixed with normal-system wiring." Install DC emergency runs in a separate raceway from AC circuits.
Disclaimer:This calculator uses standard NEC-referenced resistance values and assumes uniform load across each circuit. Final branch sizing, OCPD selection, and raceway fill are the Engineer of Record's responsibility.