After reading this article:
https://inspectapedia.com/fpe/Federal_Pioneer_Panel_Safety.php
and from it a link to this one:
https://inspectapedia.com/electric/Circuit-Breaker-Defects-Aronstein-IEEE-2018.pdf
ABSTRACT Test results presented in this paper demonstrate that some
brands of residential molded case circuit breakers do not operate
properly within the limits specified by the applicable standard. The
samples tested are both used, from homes, and new, purchased at retail
sources. The minimum trip current is determined for each breaker. The
test procedure encompasses the basic overload trip requirements of the
applicable standard. Breakers that do not open the circuit at or below
135% of rated current fail to meet the requirements of the standard.
Test results vary substantially from brand to brand. The best brands
are essentially failure free. The failure rate of the worst-case
brands is in the order of 50% for both used breakers from homes and
new breakers recently purchased. Some samples, primarily multi-pole
breakers, do not open the circuit at any level of applied current.
Failure of a circuit breaker in a home to operate properly when
required poses an increased risk of fire and injury.
I am concerned. The second article written only a bit over a year ago says that the same defects in this style of breaker are still common.
I'm considering putting in a sub panel in my garage, and would like to do the right thing. The second article is weasel worded and doesn't identify the various brands, but by implication all of the Stab-Lok type circuit breakers are flawed.
What is the best alternative type of breaker?
Best Answer
UBI is a 'replacement' stab-lok sold under various names. Chinese based company. 2/3 failed to trip below the 135% rated current.
Siemens/Murray looks about 2/3 passed at or very closely above.
Eaton, Square D and GE had no test failures.
This is NOT a huge test.
Second image is from testing 3000 breakers that were removed when renovations were done. Breakers had not been abused. (Wet, building hit by lightning, etc) and were all in service at the time of removal.
Based on this, I will go with a Square D sub panel and breakers.
Images is from the article: https://inspectapedia.com/electric/Circuit_Breaker_Failures.php