ABSTRACT
Voltage drop can be verified by measuring the voltage at the origin of the supply and then again at the furthest point on the circuit. Of course, this requires the circuit to be loaded up to its maximum. This is simple process when it is a fixed load such as an immersion heater or a room heater, but it can be more difficult if electricians are dealing with a socket outlet, cooker or lighting circuit. Calculation is by far a much simpler process, which can be done using dead test values. To carry out a periodic inspection one must have available the R1 + R2 value for each circuit. The R2 will be a conductor with a smaller CSA than the live conductors. Using the R1 + R2 value of 0.6Ω, one can calculate the voltage drop for the circuit. 0.6 × 1.2 × 20 = 14.4 volts clearly this is far too high.
