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Staircase light: two 3-way switches

Bench build · Power, transformers and three-phase · Intermediate · about 25 minutes

A 15 W lamp switched from two places with a pair of 3-way (2-way in British terms) switches. Switch one lamp from the bottom and the top of the stairs. Each 3-way switch has a COM and two travellers (L1, L2). The line goes to COM of switch A, the two travellers run between the switches, and COM of switch B feeds the lamp. The lamp is on when both switches point at the same traveller.

Staircase light: two 3-way switches: the finished build running on the simulator's bench

Build it in the labGuided build, test sheet and fault finding, free in your browser.

Parts list

Test procedure

Each test has an expected value and a pass range, like a factory test sheet:

  1. A at L1, B at L1: lamp on
  2. A at L2, B at L1: lamp off
  3. A at L2, B at L2: lamp on
  4. A at L1, B at L2: lamp off
  5. Lamp off: its holder is dead

How it works

What it does: A 15 W lamp switched from two places with a pair of 3-way (2-way in British terms) switches.

Build it (guided or ready-made), then run its test procedure below. Every test has an expected value and a pass range, just like a factory test sheet.

Background

Called "3-way" in the US and the Philippines, "2-way" in the UK. Add 4-way (intermediate) switches between the travellers and you can switch from three or more places, as in long corridors.

More builds: power, transformers and three-phase