Onset’s Accu-CT series of split-core current transformers are focused on measuring ac current and amperage in commercial building energy audits, building commissioning studies, and other similar type applications. The current sensors, manufactured by Continental Control Systems and sold through Onset, come in 20-, 50-, 100-, and 250-A versions. The units, which can be installed with one hand (even while wearing safety gloves), have a window opening of 0.75 inches. Their high phase-angle accuracy is critical for accurate energy measurements. They meet IEEE C57.13 and IEC 600440-1 standards’ full temperature range, down to 1% of rated current. The transformers are compatible with Onset’s HOBO standalone data loggers, Web-based monitoring systems, and wireless data nodes.