UL 508A  Industrial Control Panel.

The basic industrial control panel for general use. These may be open or enclosed panels.

Parts of this certification covers the components of the panel. This  includes (but not limited to) motor starters, overload relays, fused dis-connect switches, circuit breakers and the related control devices. Selector switches, pushbuttons, relays, timers, pilot light and terminal blocks, etc. Each component is verified for proper use. Markings include the "UL Listed" or "UL Recognized" designations.

Also all wiring and the wiring methods are covered under this specification. Proper wire type and size is verified for each load in the panel.

Proper labels and markings make for a complete package.

Each panel has a documentation package assuring all the requirements are met prior to placing the UL label on the panel.

Note: This is not the complete UL Specification to UL 508A.  A complete specification can be found at http://www.ul.com