These requirements cover open-type current transformers and their associated signal level combiner and/or multiplexer board accessories thereto intended for field installation within distribution and control equipment such as panelboards@ switchboards@ industrial control equipment@ and energy monitoring/management equipment@ to measure current on a branch circuit. Installation is in accordance with the National Electrical Code@ ANSI/NFPA 70. These requirements also cover ?Service Entrance? enclosed-type current transformers intended for outdoor use. These current transformers are rated to measure current in a maximum 250 Vac@ 600 Vac@ or 1000 Vac line-to-line circuits or in a maximum 1500 Vdc circuit. Transformers rated for use in an AC circuit may also be used in DC circuits that do not exceed the Vac rating. Current transformer conductor leads under the scope of this Outline are considered a Class 1 circuit@ as defined by the National Electrical Code@ ANSI/NFPA 70@ and are intended to be installed with NFPA 70 Chapter 3 wiring methods. Isolation for the user is provided at the termination. This Outline does not include investigation of the function of the controlled equipment. These current transformers have not been evaluated for accuracy or use with emergency control systems where the function of the control could affect safety. These current transformers are intended for use in an ambient temperature of 0 ?C 40??(32 ?C 104?? unless specifically indicated for use in other conditions. These current transformers are intended for use at altitudes up to 2000 meters (6562 ft) and in a humidity tolerance of 0 ?C 95 percent@ unless indicated for use in other conditions. Unless specifically evaluated and marked ??Service Entrance??@ these current transformers are evaluated for installation within equipment on the load side of the service equipment overcurrent device.