Will a QO breaker fit into a QO3100NRB, Series E01 Circuit Breaker Enclosure?
Obsolete Enclosed Circuit Breaker
No, a QO breaker could not be used in the QO3100NRB. This enclosed circuit breaker used a Q1L3100 breaker, which is obsolete and no longer available. Consider replacing with a QO3100BNRB and QO3100.