One circuit
Wire size calculator
Pick the circuit, the watts and the one-way metres from the board. The class starts where this site already plans that circuit, and steps up only when the voltage drop is past the limit.
Planning class
1.5 sq mm
About 1.7 A. Lights and fans starts at 1.5 sq mm and is checked against a 3% drop.
| Class | Drop | Check |
|---|---|---|
| 1.5 sq mm | 0.8 V · 0.3% | Within limit |
| 2.5 sq mm | 0.5 V · 0.2% | Within limit |
| 4 sq mm | 0.3 V · 0.1% | Within limit |
| 6 sq mm | 0.2 V · 0.1% | Within limit |
| 10 sq mm | 0.1 V · 0.0% | Within limit |
| 16 sq mm | 0.1 V · 0.0% | Within limit |
| 25 sq mm | 0.0 V · 0.0% | Within limit |
These figures are for planning. Cable size, the breaker and the final list have to be confirmed against the drawing, the load and the Havells datasheet.
More planning tools
House wiring costTurn rooms into points, wire length and a total once you add rates.Wire quantityTurn planning metres into 90 m Havells Lifeline Plus coils.Voltage dropCheck the drop on a chosen copper size over a one-way run.MCB selectorPick a standard breaker rating that stays within the wire class.Connected loadAdd appliance watts from the nameplate and see the total amps.Material listWrite the coils, points and board into a list you can send on WhatsApp.
Before you buy the coil
Does this use a Havells current rating?
No. The size starts from the circuit class already used on this site, then steps up when the voltage drop is past the limit. The resistance is the IEC 60228 copper figure at 70°C. The coil datasheet says what current that Havells wire can carry.
Why would a modest load need a larger wire?
A long one-way run can drop more voltage than a short one with the same load. The page shows the drop for each class from the starting size upward.