Square D PowerPact H-frame circuit breakers are designed to protect electrical systems from damage caused by overloads and short circuits Molded case circuit breakers are available with either thermal-magnetic or Micrologic electronic trip units. The external neutral current transformer is a required sensor for 3 pole circuit breaker in a system with a distributed neutral to measure the neutral current in oder to protect neutrak conducter and protect against ground faults. This current trasformer could be used with H-frame PowerPacT circuit breakers with current rating 60 to 100A The neutral current transformer is connected in the same way for unit-mount, plug-in or drawout devices, cross-sectional area is AWG 22-AWG 16.