· 3 min read
Undersized wire runs hot. Over months that heat ages the insulation, and a hot joint is where most electrical fires start. Picking the right size is the cheapest safety decision in a wiring job.
This is general guidance. Final sizes must be decided by a licensed electrician from the actual load, the length of the run and the installation method, following IS 732 and the National Electrical Code.
Typical sizes for a home
| Circuit | Typical copper size |
|---|---|
| Lighting and fan points | 1.0 – 1.5 sq mm |
| 6 A socket circuits | 1.5 – 2.5 sq mm |
| 16 A power sockets, kitchen | 2.5 sq mm |
| Air conditioner, geyser | 4.0 sq mm |
| Meter to distribution board | 6.0 sq mm or more, by connected load |
When to go one size up
- Long runs, where voltage drop becomes noticeable.
- Many wires bunched together in one conduit, which reduces how well each one cools.
- Hot locations such as roof slabs and near kitchens.
- Circuits you expect to load more heavily in future.
Use the right colours
Use red, yellow or blue for phase, black for neutral and green for earth. Consistent colours make the installation safer to maintain. Newtek house wires come in all five, from 0.5 to 6 sq mm.