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Electrical wiring simulator

Wire it wrong. See why.

Build a circuit, switch it, break it. Wirewhy solves the real currents, so you see exactly why the RCD trips, the breaker holds, or the lamp stays dark.

Open the canvas: free, no sign-up Watch the demo
  • Free to use
  • No account needed
  • English, Polski, Português
  • Computers, tablets, and phones
A traced RCD trip: numbered wires show the current that bypasses the RCD's neutral.

The devices of a real installation, drawn as in your textbook

See it in action

A lamp, an RCD trip traced wire by wire, a motor started and stopped by a contactor, a staircase timer, and an exercise from both sides: built by a teacher, solved by a learner.

It solves the circuit, not just the connections

Real currents

Every wire, contact, and load is solved as a circuit. Faults that only currents reveal are caught: a borrowed neutral, a lost PEN, a neutral touching earth.

Traced, wire by wire

A short circuit, an earth fault, or current bypassing an RCD is numbered on the canvas from the supply, so the cause is never a guess.

Protection that behaves

Breakers with curves B, C, and D, RCDs from 10 to 500 mA, fuses, and selectivity: devices trip when and why the real ones would.

Everything on one canvas

What you can do in Wirewhy today, in the browser, for free.

How it works

  1. BuildDrag devices onto the canvas and join their terminals with wires.
  2. Switch and testFlip switches, press buttons, let timers run; the simulation follows every change live.
  3. See whyEach finding explains what happened in plain words and shows where on the circuit.

From a lamp switch to motor control

Start and stop buttons with a contactor that holds itself in, impulse relays, and staircase timers that count down on the canvas. Supplies in TN-C-S, TN-S, and TT; one-way, two-way, and intermediate switches; sockets, heaters, and motors.

A start/stop circuit with a contactor holding itself in, and a staircase timer counting down.
The exercise builder: checks in plain sentences, one ending with a button pressed and released.

Exercises that check themselves

Wire the answer, pick the checks ("the lamp is on when Switch is closed", "only the RCD trips"), choose the starting point, and publish. Learners get instant, fair feedback; any wiring that passes every check counts.

Made for

Learners and exam candidates

Practise with exercises that check your wiring, and find-the-fault puzzles. Mistakes cost nothing here.

Teachers

Build an exercise with checks in minutes, share it as a link, and let a whole class follow your canvas live.

Electricians

Check an idea before it goes into a wall: what trips, what stays live, and what a customer's odd wiring really does.

Questions

Is it free?

Yes. The canvas, the simulation, exercises, sharing, and picture export are free to use.

Do I need an account?

No. Open the canvas and start. Your circuit is kept in your browser until you share it.

Which rules does it follow?

Generic training assumptions based on IEC 60364: earthing systems, protective devices, and touch voltage. Country rulesets (such as PN-HD 60364 and NBR 5410) are planned.

Does it work on a phone or tablet?

Yes. Devices, wires, and the simulation work by touch; a larger screen is more comfortable for big circuits.

Can I use it with my class?

Yes. Share an exercise or a puzzle as a link, or start a follow-along session: the class joins with a short code and sees your canvas live.

Can it replace practice on real equipment?

No. Wirewhy is a training tool for understanding circuits and faults, not a design or certification tool. Work on real installations needs a qualified electrician.

No account. Nothing to install.

Your circuits stay in your browser until you share them.

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