Engineered for heavy power distribution, the Siemens MP3B120 is a 3-pole, 1200A molded case circuit breaker. It handles the demands of commercial switchboards and panelboards. This legacy unit-mount breaker provides an exact match for older installations, restoring functionality without retrofits. The CPD63B120 is the designated replacement. Utilizing a thermal-magnetic trip, it offers precise LI protection. With 100kAIC and current-limiting features, it aggressively minimizes fault damage.
Line and Load Lugs Included, Amp-trap Current Limiters
Standards
UL 489, CSA C22.2 No. 5
Approval
CSA, UL
Temp Rating
40C
Construction Features
Current Limiting, Fused Protection (Amp-trap)
Special Features
Current Limiting (Integrally Fused)
Product FAQs
5 answers
What equipment is the Siemens CP3B120 circuit breaker designed to fit?
This legacy unit-mount breaker is engineered for heavy power distribution in Siemens commercial switchboards, motor control centers, and power panelboards.
Is there a direct replacement available for the legacy CP3B120 or MP3B120?
Yes, the Siemens CPD63B120 is the designated replacement for this breaker. It provides an exact match for older installations, allowing you to restore functionality without retrofitting your panel.
What are the wire size requirements for the lug terminals on this 1200A breaker?
The included line and load side lugs are designed to accept four conductors per phase, with a supported wire range of 250 kcmil to 500 kcmil.
How does this C-frame breaker achieve its high interrupting capacity?
The breaker utilizes a current-limiting design with integrally fused protection to aggressively minimize fault damage, allowing it to safely interrupt up to 100kA at 600VAC.
What type of trip unit is installed in the CP3B120?
It is equipped with a thermal-magnetic trip unit that provides long-time and instantaneous (LI) protection. The magnetic instantaneous trip function is adjustable to coordinate with other devices in your power distribution system.
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