The main drain pressure test is taken at what location?

The main drain pressure test is taken at what location?

• A. At the customer service entrance
• B. At the riser or lead-in
• C. In the building basement
• D. At the street main

Answer: (B)

The test is measuring the pressure where the sprinkler system is actually fed, so you read it at the riser or lead-in. This location represents the true supply to the entire system, isolating the reading to the piping that carries water to every part of the system. Testing here ensures the system can deliver the required pressure without being influenced by downstream piping, valves, or other branches. Reading at the customer service entrance or the street main could reflect upstream conditions that don’t represent the sprinkler layout, and testing inside the basement wouldn’t isolate the main feed point.

The test is measuring the pressure where the sprinkler system is actually fed, so you read it at the riser or lead-in. This location represents the true supply to the entire system, isolating the reading to the piping that carries water to every part of the system. Testing here ensures the system can deliver the required pressure without being influenced by downstream piping, valves, or other branches. Reading at the customer service entrance or the street main could reflect upstream conditions that don’t represent the sprinkler layout, and testing inside the basement wouldn’t isolate the main feed point.