Use this chart as a quick reference for the approximate current-carrying capacity of single-core copper house wires. Values are for 1100 V PVC-insulated wire (IS 694), enclosed in conduit at about 40°C ambient — the most common house-wiring condition in India.
| Conductor size (sq mm) | Approx. current rating (A) | Typical household use |
|---|---|---|
| 1.0 | 11 | Lighting circuits |
| 1.5 | 14 | Lighting, fans, light-duty sockets |
| 2.5 | 19 | 5-16 A power sockets, general purpose |
| 4.0 | 26 | Geyser / water heater, 1-1.5 ton AC, kitchen |
| 6.0 | 34 | 2 ton AC, sub-mains |
| 10 | 46 | Sub-mains, distribution-board feeders |
| 16 | 61 | Mains / heavy feeders |
Derating factors
The ratings above must be reduced when the wire runs hotter than 40°C or shares a conduit with other loaded circuits. Multiply the rating by the factor below.
Ambient temperature (PVC, base 40°C)
| Ambient temperature | 35°C | 40°C | 45°C | 50°C | 55°C |
|---|---|---|---|---|---|
| Factor | 1.05 | 1.00 | 0.94 | 0.87 | 0.79 |
Grouping (circuits bunched in one conduit)
| Number of circuits | 1 | 2 | 3 | 4 | 6 |
|---|---|---|---|---|---|
| Factor | 1.00 | 0.80 | 0.70 | 0.65 | 0.57 |
How to use: Effective rating = base rating × temperature factor × grouping factor. Example: a 2.5 sq mm wire (19 A) at 45°C with 3 circuits bunched → 19 × 0.94 × 0.70 ≈ 12.5 A.
Derating factors shown are typical industry values for guidance. Final design current and ratings should follow IS 732 and be confirmed against the APAR product datasheet.