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

In the context of UL 681, which relates to the installation and monitoring of alarm systems, the concept of "inaccessible" is crucial for ensuring the proper placement and functionality of detection devices. The standard defines a specific height for mounting where access for maintenance or inspection would pose significant challenges.

Choosing 18 feet as the threshold for being considered inaccessible aligns with industry practices and safety guidelines. Above this height, it typically requires specialized equipment or ladders to reach, which not only complicates maintenance but also raises safety concerns for installers and technicians.

A height of 10 feet is generally manageable for most individuals, allowing easy access without the need for special equipment. Similarly, 12 feet can often still be accessed with standard ladders or extension tools. Although 20 feet may seem like a reasonable option, it surpasses the standard threshold used within UL 681, making it unnecessarily high for defining inaccessibility. Thus, the 18-foot mark serves as a practical and recognized standard in the field.