ECN Forum Forums General Topics of the Trade General Discussion Area S/O cable in parrallel

Larry,

Regarding your question about where the retrofit trip modules receive power: They receive their power from breaker side CTs.

Faulty trip units should be your #1 concern. NETA recently did a study that suggested that 1/4 breakers that are currently in-service have faulty trip units installed. I believe for the most part, this study was based on 600V air circuit breakers with older dash-pot style trips installed.

Having nearly 100 breakers reach our shop on a monthy basis, we have observed #'s higher than NETA's 1/4. We noticed that nearly 50% of molded/insulated case breakers and approximately 30-40% of air breakers have faulty trip units installed.

Kind of scary.