ul standard

Depending on the exact UL certificate issued, they may have either a direct connection to an approved monitoring location or a connection to a central station. There are many variations in UL certifications for mercantile alarms. If there is a requirement for line security, such as UL Grade AA, then you must provide an approved means of supervising the connection to the monitoring location. This can be accomplished via a dedicated line, a two-way radio, or via network communication. The standard that specifies these requirements is UL681.