[Ken Streeter]

I, too, have always been puzzled by why the auto-resetting circuit breakers are permitted in the PDB, but not in the Spike. In all honesty, I don't recall ever hearing an explanation that satisfied my curiosity.

Does anybody really *know* why the rule is there, rather than just speculating as to why they think it is there?

I've heard all kinds of rumors, but still don't feel that I've really heard *why* from somebody who had inside knowledge of the reasoning used by the authors of the rule.

One "rumor" I have heard is that snap-action auto-reset breakers are not allowed in the Spike as the wider terminals of the auto-reset breaker (as compared to a standard automotive fuse) bend the Spike terminals out slightly, leading to problems when a standard automotive fuse is later used.

Originally Posted by Retired Starman

Actually, it makes a lot of sense. If you put a motor on the Spike and it pulls too much current under load, the fuse will blow, end of story.

If you have a reset breaker in there, it will snap, reset, snap again, reset, over and over again, not providing proper circuit protection and causing something else more important to become the fuse, sometimes with frightening consequences.

I do understand the difference in the two above cases. Clearly, the "single trip" breaker provides better protection.

However, if better protection is the goal, why are auto-reset breakers allowed in the PDB? Does the PDB respond to the presence of an auto-reset breaker differently than the Spike does?

I am particularly seeking to understand why it is okay to use auto-reset breakers in the PDB but not in the Spike.