Assumptions and Circuit Overview

We will assume a standard cable size of 1.5 mm$^2$ PVC insulated copper conductor for all live, neutral, and earth wires in this lighting circuit. The circuit involves two lamps (Y and X) controlled by two 1-gang two-way switches (S1 and S2). The lamps will be connected in parallel. We will describe the cable runs between the main supply point (e.g., a ceiling rose or junction box), the two switches, and the lamps.

This section carries the permanent live feed from the main supply to the common terminal of the first two-way switch (S1), along with an earth wire.

• Cable Type: 1 cable
• Number of Cores: 2 cores (Permanent Live, Earth)
• Size: 1.5 mm$^2$

This section connects the two two-way switches. It carries the two 'strapper' (or 'traveler') wires between the switched terminals of S1 and S2, and an earth wire.

• Cable Type: 1 cable
• Number of Cores: 3 cores (Strapper 1, Strapper 2, Earth)
• Size: 1.5 mm$^2$

This section carries the 'switched live' feed from the common terminal of the second two-way switch (S2) back to the main supply point, which then distributes it to the lamps. An earth wire is also included.

• Cable Type: 1 cable
• Number of Cores: 2 cores (Switched Live, Earth)
• Size: 1.5 mm$^2$

From the main supply point, the switched live (from Step 4), neutral (from the main supply), and earth wires are connected to each lamp. Since lamps Y and X are controlled together, they are wired in parallel.

• For Lamp Y: 1 cable, 3 cores (Switched Live, Neutral, Earth), 1.5 mm$^2$
• For Lamp X: 1 cable, 3 cores (Switched Live, Neutral, Earth), 1.5 mm$^2$

Here is a summary of the cable requirements for the two-way switching circuit:

• Main Supply to Switch 1: 1 cable, 2 cores, 1.5 mm$^2$
• Switch 1 to Switch 2: 1 cable, 3 cores, 1.5 mm$^2$
• Switch 2 to Main Supply: 1 cable, 2 cores, 1.5 mm$^2$
• Main Supply to Lamp Y: 1 cable, 3 cores, 1.5 mm$^2$
• Main Supply to Lamp X: 1 cable, 3 cores, 1.5 mm$^2$