This article will explore the importance of seismic resistance in cable trays, discuss when seismic braces are necessary, and help you understand how to make informed decisions for your installation. For over 60 years, the mechanical, electrical, and fire protection trades have relied on TOLCO seismic bracing solutions. Why is seismic bracing important? International Building Code. An innovative bracing system was designed to provide lateral bracing for the cable tray system. Seismic Category II cable trays and their supports are also designed utilizing the design criteria of this appendix.