Level 3 of 33 · Electrical lab
Two-way switching: a stair light
Level 3 of 33 in the Electrical lab: a free panel wiring exercise at Foundation level. Switch one lamp from two places with two two-way switches and two strappers. Either switch changes the lamp, whatever the other is doing.
Goal
The stair light is to be switched from the bottom and from the top of the stairs.
What you do
- Lock out the board at the isolator Q1: switch OFF, apply your lock and your tag.
- Prove it dead with the meter or the voltage tester, live-dead-live: prove the instrument on the proving unit, check the board reads 0 V, prove it again.
- Wire the 8 conductors of the wiring schedule. Use the wire colour your standard gives each conductor.
- Test before you switch on, in this order: continuity of the protective conductors, insulation resistance, then polarity. The Installation tester in the toolkit does all three.
- Restore power: tick the checklist, remove your tag and lock, switch Q1 ON. Then the live tests: earth fault loop impedance and, on a socket, the RCD trip time.
- Try the circuit, then run the FAT.
Done when
The factory acceptance test is marked against the panel you built.
- 8 conductors in the wiring schedule
- 4 dead checks before you touch the panel
Skills
Wiring at Foundation level.
Before you start
Level 2, One lamp, one switch, comes first. Do it first if the ideas are new to you.
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