UFC 3 -520-01
June 10, 2002
11-4.5
Ensure intercom circuit protection is listed to UL 497A and it should provide a
minimum surge current rating of 9,000 amperes. Protection should be provided on
points of entry and exit from separate buildings.
11-4.6
Fire alarm and security alarm system loops and addressable circuits that
enter or leave separate buildings should have a minimum of 9,000 amperes surge
current rating. Ensure the protection is listed to UL 497A for data communications and
UL 497B for annunciation.
11-4.7
Coaxial lines should be protected at points of entry and exit from separate
buildings. Single stage gas discharge protectors can be used for less critical circuits.
Multistage protectors utilizing a gas discharge protector with solid-state secondary
stages should be used to obtain lower let-through voltages for more critical equipment.
11-9
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