How to check illumination coverage for CHQ-WSB2 and YBO-BSB2 visual alarm devices

Applies to

• CHQ-WSB2 wall sounder beacon variants:

  • CHQ-WSB2/WL, CHQ-WSB2/RL

  • CHQ-WSB2(WHT)/WL, CHQ-WSB2(WHT)/RL

• YBO-BSB2 base sounder beacon variants:

  • YBO-BSB2/WL, YBO-BSB2/RL

  • YBO-BSB2(WHT)/WL, YBO-BSB2(WHT)/RL

• EN54-23 visual alarm device coverage checks

Summary

For visual alarm device coverage, first identify the exact product variant and EN54-23 category. For final spacing, illumination or installation decisions, use the current product-specific datasheet or application note and confirm any required control panel or CIE setting.

CHQ-WSB2 wall sounder beacon variants

• The light beam forms a 3-metre diameter cylinder from a distance of 1.05 m from the light source onwards.

• Coverage area can be calculated using the appropriate geometric formula for a cylindrical beam.

• The datasheet or application note should be used to confirm the exact calculation approach for the specific CHQ-WSB2 variant.

YBO-BSB2 base sounder beacon variants

• The light is emitted at an angle of 30 degrees from the ceiling surface.

• The illumination area A, for an installation height h in metres, can be approximated by:

A = 3πh² (m²)

Practical tips

• Use the product-specific datasheet, such as **Spec (EN)**, for certified EN54 information and performance parameters.

• Use application notes, such as **App Note 1**, for guidance on coverage calculations and installation considerations.

• Do not apply CHQ-WSB2 coverage information to YBO-BSB2, or vice versa, without checking the exact model documentation.

• Confirm the exact device code, LED colour, mounting position and installation height before using a coverage value or formula.
  

Conclusion

CHQ-WSB2 and YBO-BSB2 coverage information should be taken from the datasheet or application note for the exact model.

Last reviewed: 2026-06-16 — Reviewed by: Takashi Ishikawa