electrician.wiki
Every electrical calculation, reference and circuit.
Instant, offline, code-aware, and it shows its work. Type a question the way you would say it.
Shows its work
Every result comes with the formula, the numbers substituted and the code section behind it.
Code-aware
NEC 2017–2026 by state, plus IEC 60364 and BS 7671. When editions differ, the result says how.
Free and offline
No account, no ads, no licence checks. Install it and it keeps working in a basement.
Calculators
All calculatorsNEC field tools
IEC and BS 7671
Power and conversions
Learn the concepts
All guides- What is a transformer and how it worksWorking principle, parts, the EMF equation and turns ratio, losses, efficiency, types and who invented it.22 min read
- Ohm’s lawThe statement, V = IR and the triangle, the class 10 experiment, solved numericals and where the law breaks down.18 min read
- Power factorThe formula PF = kW ÷ kVA, lagging vs leading, what a low power factor costs and how to correct it.17 min read
- The 555 timerPinout, the inside of the chip, astable and monostable circuits and the formulas behind them.17 min read
- Voltage dropWhat causes it, the 3 % and 5 % figures under the NEC, IEC 60364 and BS 7671, and how to reduce it.16 min read
- Grounding and bonding (NEC Article 250)Grounding electrodes and rods, the main bonding jumper, EGC and GEC sizing, and subpanels.15 min read
- Earthing systems: TN-S, TN-C-S, TT and ITHow each system clears a fault, the broken-PEN risk, RCDs and disconnection times.14 min read
- All guides and code explainers →
Codes, edition by edition
As of 2026-10-14, 9 states enforce the 2026 NEC and 20 the 2023 edition. Our calculators preselect the edition used where you work.
- NEC adoption by stateWhich edition every state enforces, with sources and free data.
- 2026 NEC changesArticle 120, the 2 VA/ft² dwelling load and every number that moved.
- GFCI requirements by editionEvery 210.8 location and limit from 2017 to 2026.
- Codes by countryNEC, CEC, BS 7671, IEC 60364 and how they differ.
Pinouts
All pinoutsReference
Resistor colour codes by value
Simulator
Online circuit simulator
Animated current, oscilloscopes, logic and motors, with 360+ examples. Free, with no component limit.
Trust
Checked against published examples
Every calculator is tested against cited worked examples before each release. See the cases and our results.
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Save the tools to this device once and they keep working in basements, plant rooms and anywhere without signal. No licence check, ever.
All calculators
Every calculator page, ready to use with no signal.
Circuit simulator
The simulator and its example library, for the lab or the train.