UL 508A is the set of standards governing industrial control panels for use in the US and Canada. Underwriter Laboratories (UL) is an accredited standards developer in the electrical sphere, and the UL 508A control panel specifications are the go-to standards for municipal and electrical safety certification.
The UL 508A directive focuses on two core areas in industrial control panel design: component selection and panel design and spacing. We’ll look at those two areas later, but it is best to first outline what a UL 508A industrial control panel is, as the standard does not cover all control panels.
The official definition of a UL 508A industrial control panel is as follows:
intended for general industrial use
operating from a supply voltage of 1,000 volts or less
used in “ordinary” locations
complies with NEC ANSI/NFPA 70 code for manufacturing locations
maximum ambient temperature does not exceed 40° Celsius (104° Fahrenheit)
complies with the industrial control panel definition (two or more power/control circuits)
no rating limitation on the current state of power
These UL 508A control panel definitions are important as some other control panel types do not fall under the specification, such as:
Panel Boards (UL 67)
Access Control (UL 294)
Traffic Lights (IEC/UL 60601)
Gas/Vapor Detection (UL 2075)
Fire Protection Signaling (UL 845)
Swimming pool/Spa within 5ft of water’s edge (UL 1563)
What Does UL 508A Cover?
Having a UL mark to denote certification of a UL 508A control panel will mean different things depending on the type of control panel. For example, for an enclosed-type industrial control panel it will cover the enclosure and the components installed within it, as well as panel-mounted components and components that were mounted to the outside walls of the enclosure at the manufacturer’s facility.
For an open-type industrial control panel, it will cover only the mounting subpanel and components mounted to that subpanel at the manufacturer’s facility. For an empty enclosure (i.e., one with no components installed), only the enclosure itself is covered.
UL 508A certification can also be given for special-use panels or specific assemblies supplied together and evaluated by UL. However, it is important to note that UL 508A is a specification for the layout and application of components within an industrial control panel rather than for specific components themselves. Guidance on creating components for UL 508A control panels can be found in the UL’s Supplementary Guidance on requirements for components.
The Features of a UL 508A Control Panel
A UL508A control panel must be labeled with an approved UL label that’s applied to the construction. These standard UL Mark labels are supplied once it’s been established that the control panel meets all necessary requirements. The UL logo will be present in a circle along with the word ‘listed’.
The UL 508A control panel will also require product identification, whether it’s an enclosed industrial control panel, open-type panel, empty enclosure, etc. It should also feature an identifying control number specific to the panel shop where it was built; this could be a batch number, serial number, or catalog identifier for the product.
Where Are UL 508A Control Panels Used?
As UL 508A covers standard industrial control panels operating in normal conditions, they will be found in the vast majority of industrial settings, such as:
assembly machinery
metal-working presses
material-handling machines
plastic injection molding
crane controls
pick and place machines
packaging machines
service equipment
elevator controls
air-conditioning
refrigeration equipment
electric motors
control valves
pumps
UL 508A control panels may also be found in special use cases like
flame control
marine use (like pumping stations and naval equipment)
fountain control panels
irrigation equipment
aquatic playgrounds, swimming pools, water park rides (as long as they are 5 feet from the water’s edge)
Designing for UL508A Control Panel Compliance
As mentioned, the key focus for the UL 508A control panel guidance is the component selection and panel design and spacing.
Component Selection
The UL specifications use category control numbers (CCN), which may also have a suffix to provide further information about regional usage. The main UL ratings concern listed and recognized parts. Respectively, this means a part that can always be used in UL 508A control panels (such as DC power supplies or PLC components); and a component that can be used so long as it fits the application listed in the Supplementary Guidance mentioned above and is within the manufacturers use guidance. Non-listed components are not allowed for use unless the control panel manufacturer has been granted an exception for use.
Panel Design and Spacing
When designing industrial control panels for UL 508A compliance, the panels must have a design plan and clear labeling of wires, components, and other information such as environmental rating and short circuit rating. In addition, conductors, live, and grounded parts must be spaced appropriately, though isolation barriers may be used in limited spaces to increase the over-surface value.
Conclusion
UL 508A is a specification for designing and building industrial control panels and is a common electrical safety standard in the US and Canada. The standard outlines how control panels should be designed and with which components in order to improve operator and equipment safety. Using UL 508A products limits potential for hazardous situations including equipment or conductor overload, short circuits, or overvoltage.
Using UL-listed components and UL 508A-compliant designs helps you gain safety certification and improves your operator environment. At Enercon, we build UL 508A control panels for a wide range of general and custom uses. Since we’re a UL 508A-certified panel shop, we can guide you through ensuring your panels are UL 508A certified while taking the pressure off in-house production through our modernized OEM manufacturing facility.
To find out more about how we can meet your needs for UL 508A control panels, you can read more here or talk to our team.