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Understanding UL Levels 1 & 2

UL 634 Standard Level 1 & Level 2 High Security
ICD / ICS 705


UL-light-blue-smUL634 is the standard for all switches and connectors used in alarm systems. The 9th edition (2007) eliminated the previous BMS high security categories. Learn about the difference between High Security Levels 1 & 2. The ICD 705, sets the standards for SCIF intrusion detection systems for the government Intelligence Community, and requires Level 2 HSS devices.

Underwriters Laboratories Testing Criteria UL-634 Connectors and Switches for Use with Burglar-Alarm Systems

There are 40 standards that must be met to achieve listing to UL-634, which covers basic contacts, including Balanced Magnetic Switches, defined by UL-634 Section 3, Glossary, as: 3.2 BALANCED MAGNETIC SWITCH (BMS) – A switch that is constructed in such a manner or that includes additional components that increase resistance to magnetic, electrical and mechanical tampering or defeat.

It should be noted that while devices made with BMS provide “higher security” than standard contacts, they are not considered HIGH SECURITY CONTACTS until criteria listed below is met. In addition,there are 8 testing criteria that must be met to achieve UL-634 Level 1 HIGH SECURITY. They are included in these categories:

  • Mechanical Protection Against Tampering
  • Electrical Protection Against Tampering
  • Compromise Test – Mechanical and Mercury Switches
  • Compromise Test – Magnetic Switches
  • Compromise Test – Enclosures
  • Detection Test – measures activation distances

Additional requirements needed to meet UL 634 Level 2

Beyond the UL-634 Level 1 listing, there are 8 additional requirements that must be met to achieve UL-634 Level 2 HIGH SECURITY:

  • Made with Balanced Magnetic Switches (BMS)
  • Nuisance Alarm Test
  • Cover or Enclosure Tamper Test (When Applicable)
  • Magnet Assembly Cover Removal Alarm Test (When Applicable)
  • Switch Assembly Removal Tamper Test (When Applicable)
  • Foreign Magnetic Field Tamper Alarm Test
  • Foreign Magnetic Field Compromise Test