Labo Élec
electrical lab simulator
Exercise from the chapter "Resistor networks"
Level 4 of 5 · Skills: Calculate
An outlying garage is lit by lamps totalling 300 W and heated by a 1000 W radiator, all rated at 230 V. The installation must work at a minimum voltage of 205 V while the meter voltage is 230 V. What resistance should each of the two line conductors have, approximately?
P = 1300 W · U = 230 V · Uₘᵢₙ = 205 V
Parametric exercise: the values change with every draw; these are one example.
Guided problem in 4 steps: unknown, formula, units, data, result.
I ≈ P / U = 1300 / 230 = 5.65 A; admissible drop 230 − 205 V over the two wires: R = (230 − 205) / (2 × 5.65) ≈ 2.21 Ω per conductor.