I want to know the demand factor that a I can use in the calculation of 15 water heaters placed in different commercial spaces at a commercial place. This commercial places has the dimensions of 10' x 12' that will be used for cafeterias, souveniers, sale of books, sale of cellular accesories, etc. Each of these 15 commercial unit has a water heater but at this moment the final purpose of each unit is unknown. We don't know how many cafeterias will be or how many shoe store will be...I did not find anything related with this in the NEC, Please let me know the demand factor that I can use. Thanks