Which of the following is a standard for alarm system installations?

The correct choice relates to UL 681, which is a standard specifically established for the installation of alarm systems, particularly for commercial burglar alarm systems. This standard outlines the requirements for performance and testing of such systems to ensure they function reliably and effectively under various conditions.

UL 681 covers aspects like installation practices, operational effectiveness, and the required response to potential security breaches. Following this standard helps ensure that alarm systems are installed with appropriate measures in place to minimize false alarms and maximize security effectiveness.

In contrast, the other standards mentioned, while important in their respective domains, do not specifically address general alarm system installations. For example, UL 197 pertains to commercial power supplies, UL 501 relates to heating and cooling equipment, and UL 555 concerns smoke dampers. Therefore, while they are relevant to the safety and functionality of certain systems, they do not focus on the specific requirements for alarm system installations like UL 681 does.