One of the key parameters in the photometry of solid-state lighting is the measurement of the luminous efficacy of the device under test. This parameter requires not only accurate photometric measurements, but also accurate measurement of the electrical parameters of the device. It has become apparent that high-accuracy electrical measurements of lighting devices and solid-state lighting devices, in particular, are subject to much greater errors when the current waveform departs from a pure sinusoidal waveform. Key aspects influencing this are the calibration of the power analyser used for the measurement and the wiring arrangement used during the measurement. This paper describes a method of waveform-specific calibration for power analysers, and a simple, common error used in the wiring setup, which can result in significant errors.