[Mike Betts]

Originally Posted by Mark Jones

I'm not sure of the specs on this breaker; however, typical load center breakers (like those in your household breaker panel) are not "switching duty" rated.

This means that you cannot use the breaker as you would a light switch to frequently turn on and off the circuit, especially fluorescent lights. Most of the time, these load center breakers are intended to stay on and not switched on-and-off for many cycles.

Some load center breakers are "SWD" or "switching duty rated" to allow the breaker to be cycled many times.

Some of the issues may be due to the many cycles these breakers see and the wear of the catch nib onto the bimetallic strip.

Mark,

We (the FIRST community) have used the 120A circuit breakers for quite a few years now with few issues that were not attributable to manufacturing defects or mounting issues (see Al's post).

SWD means that the CB can handle the high inrush current associated with a florescent or switching power supply load and not necessarily a high number of switch cycles.

Besides, a typical robot sees hundreds, not thousands, of cycles.

JMHO.

Mike