I see no reason not to treat the utility as a black box, what they do should be of no concern to you. The NEC sizing of conductors, and their enforcement, only come into play after the demarcation point. Where is the utility metering being performed, before or after your main device?
Also, if the paralleled conductors do not have the same impedance the current will not divide across them equally
In my experience, utilities rarely worry about overloading their transformers, based on NEC sizing methodologies. Their protection engineers are usually involved when paralleling transformers becomes a concern.
I’m not concerned about their transformers overloading or being protected. I don’t think I’ve said anything here that should indicate that (or at least I hope not). If their transformers burn down, I don’t want to say I don’t care, but that’s not my responsibility and they can do what they want.
What I’m concerned about are the secondary conductors, which are my responsibility. The current demarcation point is the secondary terminals of their transformers. So the secondary conductors I need to care about. If one of their transformers were to fault and clear it’s primary fuse, my secondary conductors on the other transformer are only protected from overload by the primary fuse.
Agreed and understood on the different impedances causing different currents in parallel conductors. With what’s being proposed, my secondary conductors are not actually paralleled. They’re not all connected together on the source end.
Metering is before me. I believe they’re planning on doing primary metering since there are the two transformers.