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

The standard for alarm system installations is UL 681. This standard specifically addresses the testing and performance requirements for electronic burglar alarm systems. It provides guidelines to ensure the reliability and effectiveness of these systems in detecting unauthorized entry, thereby enhancing safety and security for users.

UL 681 encompasses various aspects, including installation practices, equipment requirements, and operational reliability. By adhering to this standard, installers can ensure that their systems meet the necessary quality and performance benchmarks, contributing to effective crime prevention and response capabilities.

In contrast, the other standards listed have different focuses. UL 197 pertains to electrical appliances and equipment, UL 501 addresses the performance of heating equipment, and UL 555 relates to smoke control systems. Thus, they are not applicable to burglar alarm installations, which is why UL 681 is the relevant standard in this context.