Red, black, green: the 3 wires in your home

Red, black, green: every home has these 3 wires. But what does each one actually do? 🔌

⚡ THE JOURNEY: power is made at about 11 kV, stepped UP to 400 kV to travel far (high voltage = low current = less loss on the way), stepped DOWN at substations to 33 kV and 11 kV, and finally by the pole transformer on your street to 230 V.

🔶 STAR POINT: inside the pole transformer, 3 coils (the R, Y, B phases) are joined at one point. That point is the NEUTRAL, and it is connected to earth right there at the transformer. Phase to neutral = 230 V. Phase to phase = 400 V. Your home gets 1 phase + neutral.

🔴 RED = PHASE (live): 230 V, it pushes the current. A neon tester glows on it. Your MCB and switches go on this wire.

⚫ BLACK = NEUTRAL: about 0 V, it carries the current back to the transformer. Current flows in a loop: out on red, back on black (AC, so it swings back and forth 50 times a second).

🟢 GREEN = EARTH: bolted to the metal body of your geyser, iron or fridge and run down to the earth pit. It carries 0 A… until something goes wrong. If the phase touches the metal body, the fault current runs down the green wire and the RCCB cuts the power. No earth wire? That current goes through YOU.

Note: newer wiring uses brown (phase), blue (neutral) and green-yellow (earth). Same jobs.

Stay safe: never touch live wires. Switch the MCB OFF and call an electrician.