Electrician Calculator and Code Table Reference

Voltage drop depends on the load current, the one-way circuit length, the conductor size and material, and whether the circuit is single or three phase. The standard method multiplies current and distance against the conductor's resistance characteristics and divides by its circular mil area. Voltbook does this live: set the load, distance, wire gauge, and phase, and the drop appears as both volts and a percentage with the full equation shown underneath.

The NEC treats voltage drop largely as a recommendation: informational notes suggest keeping branch circuit drop to about 3 percent and the combined feeder plus branch drop to about 5 percent, though some jurisdictions and specs make limits mandatory. Voltbook shows your computed drop against these thresholds with a clear pass-or-fail verdict, and stamps the code edition on the result so you know which basis was used.

Yes. Voltbook bundles all calculators and reference tables on the device, so nothing requires a signal — it works the same in a basement panel room, a shielded mechanical space, or a rural site. There is no account and no login either.

Conductor sizing starts from the load current, the termination temperature rating, and the ampacity tables, then gets checked against voltage drop for the run length. Voltbook's wire gauge calculator walks those inputs and returns a gauge with the reasoning shown, and the ampacity reference tables let you verify the numbers at 60, 75, and 90 degrees C yourself.

Voltbook has an explicit code edition selector covering 2017, 2020, and 2023. Tables and verdicts follow the edition you select, and every exported result carries that edition on the stamp, so an answer computed under one code year is never mistaken for another.

Conduit fill compares the total cross-sectional area of the conductors against the allowable percentage of the conduit's internal area, which depends on the number of wires. Voltbook computes it from the conduit type and size plus your conductor list, and shows whether the fill passes the applicable limit.

Box fill counts volume allowances for each conductor, device, clamp, and ground present in an outlet box, then compares the total against the box's cubic-inch capacity. Voltbook's box fill calculator adds these allowances up for you and shows the arithmetic, so the answer is checkable rather than a bare pass or fail.

Yes. Voltbook bundles searchable ampacity tables with columns for 60, 75, and 90 degree C ratings, along with AWG wire charts, conduit fill tables, and conductor properties. All of it is offline, filterable, and tied to the code edition you select.

Ohm's law relates voltage, current, resistance, and power: enter any two and the rest follow — for example, current equals voltage divided by resistance. Voltbook's solver accepts whichever pair you know, computes the remaining values instantly, and displays the exact formula it applied.

Yes. Every Voltbook result can be copied or shared as a PDF stamped with the inputs, the formula, and the selected code edition. That gives you a clean record to send to a foreman, attach to a job file, or hand to an inspector.

Many do not, which makes their answers hard to trust or verify. Voltbook renders the live equation with your actual numbers substituted in, directly beneath every result, so you can check the math against the published formulas yourself.

No. An app is a calculation aid and quick reference, not a substitute for the official code or your local amendments. Voltbook is built for licensed professionals and says so in the app: verify all results against the currently adopted code and your authority having jurisdiction before acting on them.