Here is my take on it: The specifications that I issue call for Arc Flash and Selective Coordination analyses to be the responsibility of the EC. However, in order to conduct those two analyses, you have to first gather all the information needed to perform a Short Circuit Study. Therefore, to avoid duplication of effort, the specs call for the EC to do it all.
But to be clear, I am not asking the EC to take on the professional liability, nor am I asking theEC to perform engineering work. Rather, the specs say that the EC is to subcontract this effort to their chosen equipment vendor. That vendor will either have a PE on staff, or will subcontract the analyses to an engineering company. The liability therefore resides where it belongs: to the PE who signs and seals the analyses.
Here’s why I think this is the right approach. First, let’stalk about projects delivered on the “design – bid – build” method.
As the Engineer of Record, I will not be able to know which EC will win the bid, or what equipment vendor that EC will select. If I were to try to perform an Arc Flash or Selective Coordination analysis, I would need to know the exact make and model of all the breakers in the distributions ystem. I can’t know that when I issue the drawings for bidding. So I have to assign this to the EC.
Some jurisdictions require that the design include all the related analyses. In those instances, I will select a set of components as the “design basis,” and my analyses will demonstrate that that set of components will meet the requirements (e.g., panel ratings are above calculated SCC values, breakers selectively coordinate, etc.). The design package will include a statement that if the successful EC chooses any different components, then the EC becomes responsible for redoing the analyses.
Now let’s discussthe “design – build” and “design – assist” delivery methods.
This can go either way. I can do the analyses, provided only that the EC gives me all the information I need with regard to distribution system components (make, model, breakers, cable distances, etc.). The EC could instead sub this out to the equipment vendor. I am very quick and efficient at the Short Circuit Calculations. But the Arc Flash and Selective Coordination studies can require several iterations of selecting breakers, running the analyses, seeing what worked and what didn’t, selecting different breakers, rinse, repeat. The equipment vendor will know their equipment far better than I ever could. It is more efficient to give that work to the vendor. And here again, if a person has set up a computer model to run those two analyses, then to also run the Short Circuit Calculation is nothing more than one more pushing of a button.
