1. What is UL508?
UL508 is a UL standard related to industrial control equipment.
Examples of products covered under this category include relays, timers, and programmable controllers.
There are three types of UL certifications: Listing, Recognition, and Classification.
- -UL Listing
The product is recognized by UL as a final product. - -UL Recognition
The component is UL-certified with conditions for being used inside other equipment - -UL Classification
The product is UL-certified for specific applications or conditions.
For UL508, Listing certification is mainly required. This requirement is generally based on the needs of local U.S. electrical contractors and manufacturers of UL-certified equipment.
2. Difference between UL508 and UL62368-1
The major differences in power supply requirements between UL508 and UL62368‑1 are summarized in Table 1.
Table 1 Comparison of Power Supply Requirements
| No | Standard | UL508 | UL62368-1 |
|---|---|---|---|
| 1 | Crepage and Clearance Distances |
Defined based on input voltage. Example: Vin = 240 V |
Defined based on internal operating voltage. Example: Operating voltage = 250 Vrms |
| 2 | Insulation Thickness |
Direct support (parts that directly hold bare live conductors) requires a thickness of 0.71 mm or more. Example: Terminal blocks |
No thickness requirement for functional or basic insulation. For reinforced insulation constructed with a single layer, 0.4 mm or more is required. |
| 3 | Terminal Blocks | Terminal blocks must be UL-certified for field wiring. Additional evaluation is required if not already certified. |
No UL field wiring certification requirement for terminal blocks. |
3. UL508-Certified Products from Our Company
Some of our products have obtained UL508 Listing certification.
Please refer to the catalog sections “Applicable Standards” and “Safety Standards” for details.
