ElectraSim is a free online electrical wiring simulator for building and testing realistic circuits directly in your browser.
A complete electrical circuit toolkit — all running locally in your browser, no server, no cloud, no account needed.
Place MCB breakers, switches, light bulbs, fans, motors and sockets from the palette. Components snap to a grid for clean, professional layouts.
Hit Run and watch electricity flow instantly. Energised wires animate, bulbs light up, fans spin. Toggle switches and see changes propagate live.
Trace open and short circuits, then inject reverse-polarity and missing-earth faults for practice. Fault states highlight clearly for faster diagnosis.
Click a port to start wiring — ElectraSim auto-routes orthogonal wires around components. Custom multi-step wiring also supported.
Shift-click or drag-select multiple components. Align left, center, right, top or bottom with one click for professional diagrams.
Save your circuit as JSON, export as SVG or PNG, or generate a shareable URL. Your work is autosaved locally and survives page reloads.
No account, no download, no setup. Open ElectraSim and start building immediately.
Click "Launch the Simulator". It loads instantly — works offline after the first visit.
Open the Components panel and click any component — MCB, switch, bulb, fan — to place it on the canvas.
Click a port dot on one component, then a port on another. ElectraSim routes the wire automatically.
Press Run to simulate. Toggle switches, add faults, and see exactly how your circuit behaves.
ElectraSim is designed for anyone who wants to understand or teach how electrical circuits work.
Use a beginner-friendly circuit simulator free of charge. Practice house wiring online without risk of shocks or blown fuses.
Create live circuit demonstrations in the classroom. Share circuits via URL for homework assignments.
Use it as electrician training software to prototype layouts, demonstrate fault scenarios, and validate circuit logic before going on-site.
Experiment with circuit ideas, test different configurations, and learn by doing at your own pace.
Step-by-step guides to help you learn electrical wiring online — from household circuits to fault detection. Written for beginners and professionals alike.
ElectraSim v1.6 adds dark mode across the app and website, a new RCBO component, a realistic push button, and a clearer simulator comparison guide.
Read article → Beginner GuideLearn how momentary push buttons work, the difference between normally open and normally closed contacts, and how they control doorbells and machinery.
Read article → Electrical SafetyFlickering lights can mean a loose bulb, an LED and dimmer mismatch, or a wiring fault. Learn safe checks, warning signs, and when to call an electrician.
Read article → Wiring GuideReverse polarity, missing earths, overloaded rings — these five wiring mistakes are found in thousands of UK homes. Learn what they are, why they're dangerous, how to spot them, and how to test your own circuits safely.
Read article → Wiring GuideRing circuits and radial circuits are the two ways to wire socket outlets in UK homes. This guide explains how each works, when to use each, cable sizes, spur rules, and how to simulate both topologies in a free browser-based circuit simulator.
Read article → Beginner GuideWhat do the brown, blue and green-yellow wires actually do? This complete guide explains the roles of live, neutral and earth in UK wiring, what happens when they're mixed up, and how to safely explore all three conductors in a free circuit simulator.
Read article → Wiring GuideTwo-way switching lets you control one light from two locations — the classic staircase circuit. This guide explains exactly how two-way switch wiring works, the role of COM, L1, and L2 terminals, strapping wires, and how to simulate the full circuit in a free electrical circuit simulator.
Read article → Beginner GuideThe distribution board is the heart of every electrical installation. This guide explains what's inside a consumer unit, how it distributes power to every circuit in a building, and how to simulate a multi-circuit distribution board using a free electrical circuit simulator.
Read article → Beginner GuideA contactor is an electrically controlled switch built for high-power loads. This guide explains how contactors work, where they're used, how they differ from relays and MCBs, and how to simulate a contactor circuit in a free electrical circuit simulator.
Read article → Beginner GuideAn RCD can disconnect a dangerous earth fault fast enough to save your life. This guide explains exactly how Residual Current Devices work, why they're mandatory in modern wiring, and how to test RCD protection safely using a free electrical circuit simulator.
Read article → How-to GuideNew to ElectraSim? This step-by-step guide shows you how to place components, draw wires, run a simulation, and read the fault log — all in your browser, for free.
Read article → Beginner GuideLearn how household electrical wiring works — from the main circuit breaker panel to your light switch. Understand live, neutral and earth wires, how MCBs protect your home, and what causes common faults.
Read article →The free virtual electrical lab used by students, teachers and electricians. Simulate circuits online — no download, no sign-up, no risk.
⚡ Launch ElectraSim Free