Electrician Apprentice Formula Sheet
This page is designed for bookmarking. It is not a substitute for standards or classroom notes, but it gives apprentices a quick map of the calculations they should understand.
| Topic | Formula | Use |
|---|---|---|
| Ohm’s Law | V = I × R | Relationship between voltage, current and resistance. |
| Power | P = V × I | Single-phase resistive load power estimate. |
| Energy | kWh = kW × hours | Energy consumption over time. |
| Three-phase apparent power | S = √3 × VL × IL | Balanced three-phase load estimate. |
| Transformer ratio | Vp/Vs = Np/Ns | Relates voltage to turns ratio. |
How to use formulas properly
Write the known values with units, draw the section of circuit the calculation applies to, rearrange before substituting numbers, and check whether the answer is physically sensible.