About current calculator
Current, measured in amperes, is how much charge flows each second. It decides wire thickness and fuse ratings.
Formulas
- I = V ÷ R.
- I = P ÷ V.
Example
A 1,500 W heater on 230 V draws about 6.5 A. Wires and sockets must be rated above that.
Safety margin
Choose cables and fuses rated for more than the expected current, following local electrical rules.
Another worked example
A 1,000 W kettle on 230 V draws about 4.35 A. A 12 V supply across a 6 Ω resistor drives 2 A. Add up the currents of everything on one circuit to check that the total stays below the breaker rating.
Cable and fuse choice
Wires heat up as current increases. Choose cable and protection rated above the maximum current, as set out in your local electrical code.
