Rated 25 kAIC at 480V, the Siemens JJ3B300 is a 3-pole, 300A molded case circuit breaker designed for legacy power distribution systems. It utilizes a proven thermal-magnetic trip mechanism with adjustable magnetic functions, providing dependable protection for commercial loads. This bolt-on breaker mounts into Siemens P4 and P5 panelboards, SB switchboards, and FC-series interiors. As a direct cross-reference for the JXD63B300, it ensures a perfect fit without aftermarket adapters.
Which Siemens panelboards and switchboards are compatible with the JJ3B300 breaker?
This J-Frame breaker is designed for use in Siemens P4 and P5 panelboards, SB switchboards, and FC, FCI, and FCII distribution interiors.
What wire sizes are accepted by the standard lugs on the JJ3B300?
The standard lugs accept aluminum or copper conductors ranging from 3/0 AWG to 500 kcmil.
Does the JJ3B300 feature an adjustable trip setting?
Yes, it features a thermal magnetic trip unit with a fixed thermal element for long-time overload protection and an adjustable magnetic element for instantaneous short-circuit protection.
Is the JJ3B300 rated for direct current (DC) systems?
Yes, this breaker is rated for use in DC applications up to 250VDC, providing a 20kA interrupting capacity at that voltage.
How is the JJ3B300 installed into the distribution equipment?
It utilizes a bolt-on connection to secure directly to the busbars of compatible Siemens and ITE panelboards or switchboards.
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