HARTING Technology Group

UL 508A - Best Practices

Building a UL 508 cabinet requires a lot of planning.  Below are some best practices for developing a UL 508 cabinet.

Familiarize Yourself With the UL 508 Standard

If this is the first time you’ve built a UL 508 cabinet, you will have a lot to do to ensure compliance.  The best place to start is the UL 508 website.  The entire UL 508 standard is available for purchase here.

Also listed are standards that are referenced by UL 508, such as UL 2237 the standard under which UL listed HARTING components fall.

Select all the physical components you will need and layout your cabinet:

1. Look at your customer specifications and select the right enclosure and components to meet them.

2. Develop layout drawings with all the components to ensure they fit.

3. Develop wiring schematic drawings for components.

4. Order the selected components and enclosure to determine the earliest production start date.

Coordinate wire sizes and component types

Base your wires size on load current and circuit protection on wire size.  Wire size determines how the current load(s?); while the correct circuit protection insures high load current prevents overheating, which poses a fire hazard. 

Select components based on voltage and load current and component type based on function. Component size dictates voltage and load current possibility; component type determines functionality.

Choose the Best Control Type for Your Needs

As a general rule of thumb, you should start with simple components (such as relays and timers) and move to components with more complex functionalities (like programmable Smart Relays or Programmable Logic controllers [PLCs].  Complex controls provide significantly more functionality(;) also significant programming time.

How to Choose the Best Operator Device Type for Your Needs

Again, always start with simple operator devices (Pushbuttons, Pilot Lights, Digital Panel Meters, etc.). More complex solutions, such as a color touch screen display as the Human Machine Interface (HMI) can be added as needed. This provides significantly more functionality, but it also requires a computer and programming software and someone who knows how to use the software to program the desired functionality.

Use UL to Pick the Right Components:

UL lists, to the manufacturer’s part number, components that have been certified.  Using the referenced standards to UL 508 (as listed on their website) fast-tracks your design for UL 508 certification. 

Best in class suppliers will make it easy for you to find the parts that you need.  For example, all of HARTING’s part numbers can be found on our UL 508 website.  Such documents include:

Connectivity Solutions for UL 508 Applications under UL 2237 Catalog
PVVA UL Listed Cable Assembly Approvals
PVVA2 UL Recognized Component Approvals