NEC Commercial Electrical Practice Test

What characterizes a non-linear load?

1. Constant energy consumption

2. Fluctuating voltage readings

3. Wave shape of current not following voltage

4. Efficient power factor

The correct answer is: Wave shape of current not following voltage

A non-linear load is characterized by the wave shape of current not following voltage. In a non-linear load, the current does not change proportionally with the voltage, which means that the current waveform is distorted compared to the voltage waveform. This distortion typically occurs because non-linear devices, such as computers and LED lighting, draw current in short bursts rather than in a smooth, continuous manner. This property can lead to harmonic distortion, which impacts the quality of power in the electrical system. When these loads are connected to the electrical supply, they can create additional currents at frequencies that are multiples of the fundamental frequency, thereby affecting the overall system performance. The other options do not accurately define a non-linear load. For instance, constant energy consumption pertains more to linear loads or average consumption rather than the distortion effects related to wave shape. Fluctuating voltage readings can result from many factors and aren't a defining characteristic of non-linear loads. Lastly, a power factor that is described as efficient usually relates to linear loads where current and voltage are in phase, which contrasts with the behavior of non-linear loads that complexity the power factor due to harmonics.