How should control sequences and interlocks be addressed in the Cx plan?

• A. Only document the main on/off control.
• B. Include a verified sequence of operations, interlocks, alarms, and expected behavior; test during commissioning.
• C. Interlocks are not required in Cx plan.
• D. They should be tested after occupancy, not during commissioning.

Answer: (B)

The main idea is that a commissioning plan must cover the full control sequences and safety mechanisms, not just a simple on/off setting. A comprehensive Cx plan documents the complete sequence of operation, the interlocks that enforce safe or correct states, the alarms that alert operators to faults, and the expected behavior of the system. Verifying all of this during commissioning ensures the system operates as designed, interlocks prevent unsafe conditions, alarms function correctly, and the overall sequence is validated before occupants use the building. This proactive testing helps catch issues early and reduces risk during occupancy.

Documenting only the main on/off control misses how the system should behave in normal and fault conditions, and it ignores interlocks and alarms that are essential for safe and reliable operation. Claiming interlocks aren’t required contradicts the purpose of interlocks in coordinating safety-critical sequences. Testing only after occupancy postpones validation until after the system is in use, which can lead to disruptions and undetected issues that should have been resolved during commissioning.