So, is there an infinite amount of amps that can come into a house panel that has no main? There is no limiter of any kind in a meter ? Or is there an OCPD on the pole? Without main breaker like so many of these older panels, what keeps the panel from overloading when homeowners gradually add circuits and overload the panel rating? Thank you
Not a simple yes or no answer.
Many old homes never have a problem because the load just isn't there.
The main overcurrent device is there to protect the conductors more so then to justify size of the service.
Current is limited by the capacity of the supply at least to some extent, put 50 or 60 kVA of load on a 10 or 15 kVA transformer and chances are it will trip something at some point, it will ordinarily trip proper service overcurrent protection first though if talking about old undersized service
However keep adding load to an old house with 60 or 100 amp supply conductors that happens to be on a 75 or 100 kVA transformer (likely has other customers supplied as well) and you have nothing to keep from overloading those conductors if there isn't proper main(s) to protect them.
I am about to start working on an upgrade to a facility that will only have about 200 kVA of calculated load. POCO is going to provide a 225 kVA transformer, but my service equipment will be able to handle a little more then double that amount. If significant load is ever added POCO will likely need to upgrade their transformer.