The fixture load of a 4 inch branch interval is based on _______________ per inch per foot fall.

The fixture load of a 4-inch branch interval is based on 1/4 per inch per foot fall. This measurement is crucial in plumbing calculations as it helps determine the capacity and sizing for drainage systems. Specifically, this load factor indicates how much drainage capacity is expected from a specific size pipe over a given distance. By utilizing the 1/4 fall per foot, plumbing professionals can ensure that wastewater flows effectively towards sewer systems, minimizing the risk of blockages and ensuring optimal drainage performance.

Other factors, such as the dimensions and slope of pipes, need to be adhered to according to plumbing code standards, but the 1/4 rule is a fundamental aspect that directly impacts the efficiency and functionality of plumbing systems when sizing and installing branch intervals.