Insurance Services Office (ISO) is an independent company that analyzes the structural fire suppression delivery system provided in communities. A Public Protection Classification (PPC) number is determined based on the analysis, and insurance companies use PPC information to help establish fair premiums for homeowner and commercial fire insurance. With a split Class 3/3X all properties located within 1,000 feet of a fire hydrant and within 5 road miles of a staffed fire station will use Class 3. All properties located further than 1,000 feet of a fire hydrant and within 5 road miles of fire station will use Class 3X. Assuming all other factors are equal, the price of fire insurance is, in general, lower in communities with a good PPC than in those with a poor PPC. Public Protection Classification numbers range from 1 to 10. The highest rating a fire suppression program can receive is a Class 1. Programs with a Class 10 rating do not meet the ISO’s minimum criteria. Large commercial building may be evaluated separately and receive an individual PPC rating. ISO Letter