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The basic supply circuitWhere do your 230 volts actually come from?

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The question at the end: Where do your 230 volts actually come from? The answer is in the notes below.

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This diagram comes up again and again. It shows where your 230 V actually comes from.

transformer winding 230 V LINE (brown) NEUTRAL (blue) · 0 V 0 V star point → EARTH LOAD e.g. lamp 230 V 0 V 230 V dropped across the load
One end of the supply transformer's winding is the star point, which is connected to earth and held at 0 V. The other end is at 230 V. The line (brown) carries 230 V to the load, and the neutral (blue) returns at 0 V. The full 230 V is dropped across the load.
  • The star point is where the neutral and earth join at the transformer. From there it goes down into the ground. The electricity doesn't disappear: it's a continuous loop.
  • The coil in this drawing is the transformer's secondary winding. The secondary side is always star.
  • A circle with an X is the symbol for a lamp. Lamps are resistive loads.
  • The symbol with three horizontal lines is earth (ground).
  • It's called line (it used to be called phase), not "live". Both the line and the neutral are live conductors, and you can get a shock from either.
Cable colours (current UK harmonised): Line = brown · Neutral = blue · Earth (CPC) = green/yellow · on 3-phase: L1 brown, L2 black, L3 grey.

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