According to UL 681, what distance above the ground is considered inaccessible?

The correct choice of 18 feet as the distance above the ground that is considered inaccessible is grounded in the standards set by UL 681. UL 681 is a standard that outlines the requirements for burglar alarm system installation and operation, and it includes specifications regarding the placement of components to ensure they are not easily tampered with or accessed by unauthorized individuals.

By defining inaccessible height as 18 feet, the standard aims to ensure that sensitive components, such as detectors and alarm systems, are installed at a height that makes it challenging for an average person to reach them without the use of a ladder or specialized equipment. This is significant for enhancing the security of alarm systems, as it reduces the likelihood that someone could disable or damage the system without drawing attention.

Installation at this height also correlates with general security principles, which suggest that the more difficult it is for a potential intruder to access security devices, the more effective those devices will be in preventing unauthorized access. Consequently, using 18 feet as the threshold for inaccessibility is a calculated decision intended to maximize security in alarm system design and installation.