I hope I'm in the right place. Could someone please explain what. (110.9-110.10) Provide short circuit current, impedance and component ratings at supply terminals. I don't understand what I'm to provide? Thank You
You need to select the ratings of the equipment, i.e. interrupting rating of the breaker, that can handle the amount of available fault current.
You also need to be aware of the overcurrent devices, and system characteristics, to know that the equipment furnished will protect the equipment in the event of a multiple line fault or line-to-ground fault.
Essentially, you contact the utility, and ask them for the short circuit current, and system impedance at the point of interconnection of the service. if there's a transformer involved make sure you get the info on the low voltage side where you will be connecting too. Then you use those numbers and your system design information, including cable, motors, and so forth, to determine the fault current at various points in the electrical system you are installing. The more detail you have the more accurate information you will get from the study.
Make KAIC selection of equipment based on the maximum fault levels at each point.
Once all this is done, now you have to go back and determine the proper settings for any device that has adjustable trip settings to ensure the protective devices will coordinate, i.e. the main will not trip on a branch circuit fault.
If this is the first time for you doing this, it would probably be prudent to consult with someone with this area of expertise.
