House wiring: which wire size for which circuit?

Choosing the right wire size keeps circuits safe and prevents heating. Always have wiring designed and installed by a licensed electrician; this guide helps you understand the bill of materials.

Typical sizes in homes

Circuit	Common copper wire	Typical MCB
Lights and fans	1.0–1.5 sq mm	6 A
Plug points (6/16 A)	2.5 sq mm	16 A
Geysers, ACs	4 sq mm	20–25 A
Main incoming supply	6–10 sq mm or as per load	As per DB design

FR, FRLS or HFFR?

• FR (flame retardant) resists the spread of fire.
• FRLS also gives off less smoke — a good default for homes.
• HFFR / zero-halogen releases no toxic halogen gases; preferred for hospitals, offices and premium homes.

Buying tips

• Wires usually come in 90 m coils; keep separate colours for phase, neutral and earth.
• Use conduits and junction boxes rated for the wire count.
• Pair wiring with RCCB/RCBO protection for wet areas.