Intermediate Switching
Three or more switching points — landings and long corridors.
● Line● Neutral● Earth
Tap any wire, switch or device to see what it is.
Useful Information
A 2-way switch at each end, with one or more intermediate switches in the strappers.
The intermediate either passes strappers straight through or crosses them.
Important to know
- Intermediate terminals are paired: strappers IN on one pair, OUT on the other — check the manufacturer's marking.
- Identify all strapper cores brown (514.3.2).
- Add as many intermediates as needed — the logic stays the same.
Common faults
- Lamp ignores the intermediate — strappers in on the wrong pair (IN/OUT mixed).
BS 7671:2018+A4:2026 references
514.3.2643.2643.6
Study notes paraphrased — check against your copy of BS 7671.