IES LM-28-2012 is a revision of the 1989 report of the same name. It has been revised primarily to acknowledge technological changes that have occurred in electrical measuring instrument design and interfacing. This guide defines the terms that are used to describe the instruments, and informs the reader about caution that must be taken when selecting, maintaining, and using electrical instruments in the photometric laboratory. Additionally, this guide will aid in the evaluation and application of electrical measuring instruments while maintaining appropriate levels of uncertainty.