@SteveH posted:I'm inclined to believe there's little benefit to choosing a smaller breaker for added train protection, if the selected instant breaker is rated approximately 20% less than the Postwar transformer's maximum output current. Thoughts?
There can be perfectly acceptable scenarios that lend themself to having a ZW with four 10A breakers hanging off of it and there are others where that would be inappropriate. That is why I always recommend, with the goal of protecting the downstream equipment, one sizes the instant breakers to the downstream load and never let the total load exceed the transformers capabilities (sure a 20% de-rating parameter can be utilized in determining the capabilities).
