I want to add to this. I mentioned in another thread, that there is TWO stock numbers for the 100 amp breaker in the 003 parts TM. I have been snooping around, and now I know why. And perhaps this truly has something to do with some people being able to drop a "shock load" on the MEP-003A, and sometimes it pops the CB, and sometimes not.
In the 5 KW parts manual, the NSN for the breaker is: 5925-01-050-0484, (no UOC). The NSN's for the CB in the 10 KW parts manual are, 5925-01-050-0484, (same as the 5 KW, but with a UOC, of A&C) and the second number is: 5925-01-097-4925, (UOC B). I looked up the UOC, (Usable On Code), and it tells me that only certain serial numbers get the CB 5925-01-097-4925. But not WHY they do. So I went back to basics. Looked at the 5 and 10 KW parts manuals again, but this time followed my own rule #1. Look at the cover. Look at the explanation of the UOC's. And then it became clear.
There is only one model 5 KW gen set, Model MEP-002A. A 60 hertz machine. Then looked at the 10 KW book, and saw that it was listed as two different machines. MEP-003A and MEP-112A. I have known this for 40 years. But assumed, (something that always gets me in trouble), that the 5 KW also had TWO models. Why I assumed this, I just don't know, but I guess after looking at this TM 10 billion times in the last 40 years, I was looking, but not SEEING. Then I looked at parts. The UOC, B coded 10 KW machine had no 110 volt outlet. its 400 hertz.
The NSN for the RIGHT CB, for both the 5 &10 KW is 5925-01-050-0484. Its for a 60 hertz machine. The NSN 5925-01-097-4925, is ONLY for 400 hertz machines.
Over the last million years, lots of people have scrapped the 400 hertz machines, and used parts to fix their 60 hertz machines. And lots of people who look at a parts TM, may sometime not LOOK at the UOC, and order the 400 hertz CB. Sadly, the FEDLOG doesn't give a technical breakdown of the CB's characteristics. Perhaps the 400 hertz CB pops earlier? Perhaps the 60 hertz CB pops earlier? I don't know. What I do know is that it might not hurt to look at the NSN or better yet the part numbers on the CB's to see if this could be a reason why some pop when they do not exceed the rated current.
5925-01-050-0484
Part number: 72-5173 or CD3-Z142-1
5925-01-097-4925
Part number: 72-5174 or CD3-Z75-5