Zinsco RC38-40 Miniature Circuit Breaker

The Connecticut Electric UBIZ0240 is the direct cross-reference for the obsolete Zinsco RC38-40. It provides the same 40A, 2-pole configuration and fits standard Zinsco load centers.

The RC38-40 is a thin series breaker that occupies a single 3/4-inch space in a Zinsco load center, despite being a 2-pole breaker.

Yes. The RC38-40 is built with a common trip function and a factory-installed handle tie. This ensures that an overload or fault on either pole will disconnect both legs of the 240V circuit simultaneously.

Yes. Legacy Zinsco panels and breakers have a documented history of failing to trip under fault conditions and experiencing busbar arcing. Many licensed electricians recommend a complete panel upgrade rather than replacing individual breakers.

It is compatible with specific Sylvania, Challenger, and Thomas & Betts panels that were manufactured using the original Zinsco plug-in design. Always verify the panel label for approved breaker types before installation.

The terminals accept 8 AWG to 4 AWG copper or aluminum conductors. When terminating aluminum wire, electricians should apply an approved oxide inhibitor to prevent corrosion and ensure a secure connection.

The 10kAIC rating specifies the maximum fault current the breaker can safely clear. It is certified to interrupt up to 10,000 amps of short circuit current at 120/240V without catastrophic failure.