California Alarm Company Operator Licensing Practice Exam

Alarm panels are a continuous-load situation, meaning the power supply runs almost all the time. The recommended approach is to size the transformer so the expected load uses only about 80% of the transformer's rated output. That 20% margin provides headroom for startup surges from devices like keypads or sirens, voltage variation as the supply ages, and any small future additions to the system. It helps keep the transformer from overheating and ensures reliability over time. If you sized to 100% of the transformer, there’d be little to no room for peaks or aging; sizing much smaller than the load would be wasteful and underutilize the capability. Using about 80% of the rating strikes the right balance.