Oh, yeah. I had missed that the first time around due to the lack of grammar. In the initial post, s/he mentioned it not sounding right. I hadn't considered that tripping breakers might equal "not sounding right."
Either way, the solution is the same -- new branch circuit.
your comment about grounding and 100 amp is irrelevant. Grounding was required long before 200 amp services were common.
I dunno. Our new house was built in 1971 with 125 amp service and 12-2 & no ground wire throughout. I've seen references to the NEC of 1962 requiring grounded branch circuits, but it was clearly at least 10 years before it was implemented in my area. Our old house was wired in the 1950s and had 150 amp service.