I've rented a space where the transformer and main panel are fenced off and I can’t access it without calling the landlord. He lives rather far away and is the only one with the key and that kind of potential downtime would be catastrophic for my business, however I do need to pull a lot of power consistently and will be pushing it as hard as I can which means I might occasionally trip on hot days.
The hypothetical setup is as follows: A new 125 A cutler hammer breaker on the service side A new 125 A square d breaker backfeeding our main sub panel (in our building) About 120 feet of underground 3/0 aluminum between the two
My question is: If our equipment pulls more that 125 A which breaker trips first, the one on the service side (outside) or the one on the load (in our building) or both?
If the answer is the one on the service side or both (or either depending on manufacturing tolerance variation or whatever) my followup question is: Is there any way we can purchase or modify our inside 125 A breaker to flip at ~123 A so that it always flips first?