Tools · Field Calculators
Electrical Tools
Practical, NEC-based calculators from a contractor that self-performs the work. Free to use — no sign-up, and nothing is stored. Pick a calculator to get started.
Free Calculators
Built by people who pull the wire
Quick estimates for the field and the takeoff. Each tool shows its method and the code reference it’s based on. For design and permit documents, rely on a stamped engineering calculation — our engineering team runs the full studies.
Voltage Drop Calculator →
Copper or aluminum, 14 AWG to 1000 kcmil. Single- or three-phase, any voltage, length, and current — with NEC 3% / 5% recommendation flags.
RacewayConduit Fill Calculator →
THHN/THWN-2 in EMT, IMC, Rigid, or PVC, checked against NEC Chapter 9 (53/31/40%) — plus the smallest conduit that fits.
AmpacityWire Ampacity Calculator →
NEC Table 310.16 ampacity for copper and aluminum, with ambient-temperature correction and conductor-bundling adjustment.
BoxesBox Fill Calculator →
NEC 314.16 box volume from conductors, devices, clamps, and grounds — compared to your box’s cubic-inch capacity.
Service SizingResidential Load Calculator →
Whole-house load and service size by the NEC 220.82 optional method — a free educational tool (we’re a commercial contractor).
PanelsPanel Schedule →
Build a printable panel schedule — main breaker or main lug, any size and spaces, with breaker, poles, and description per circuit. Print or save as PDF.
NEC & Fire CodeCode Assistant →
Ask NEC and fire-code questions and get plain-language answers with section citations and worked examples. NEC 2017/2020/2023 — verify with your AHJ.
Tucson Electric PowerTEP Standards →
TEP service requirements, meter/grounding guidance, and an AI assistant grounded in TEP's published guidance — built for local contractors.
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