For a while, Schneider Electric has been manufacturing the FPE Stab-Lock breakers with colour coded handles.
You can see the red ones at:
https://www.electrical-contractor.net/ubb/Forum5/HTML/001123.html The black ones were likely made before the coloring scheme.
The colouring scheme matches the colours typical of Edison plug fuses;
Blue=15A
Red=20A
Green=30A
Grey=40A
Above that black handles are used.
AFAIK, the prograssion of the NC stab-loc breakers in Canada:
1970s: Blabc body, square black toggle.
Sometime in the late 70s they had the orange tipped toggles for a while.
In the late 80s, they came out with the white bodies. In the mid 90s, they began colour coding the handles on 40A and less breakers. Late 90s, they switched from the "squared" toggle to a flatter toggle, retaining color coding.
