Building a UL508A control panel means assembling UL Listed and UL Recognized components inside an enclosure and marking the finished panel with a short-circuit current rating. Functional Devices, Inc. does not sell or build finished panels. We do, however, manufacture panel components: RIB® (Relay-In-a-Box®) relays, transformers, power supplies, and enclosures.
What a UL508A Control Panel Requires
UL508A is the Standard for Industrial Control Panels. A panel falls under this standard when it consists of two or more power circuit or control circuit components inside a single enclosure. A single device in a box does not qualify as a UL508A panel.
Every component in the panel has to be either UL Listed or UL Recognized and appropriate for the application. A UL Listed component is a complete, standalone product evaluated for use as installed, such as a power supply. A UL Recognized component is an incomplete building block evaluated only under stated Conditions of Acceptability, such as a terminal block.
The finished panel is assembled, tested, and marked by a UL508A-authorized panel shop, which applies the panel’s listing mark. Functional Devices supplies the components.
Where RIB® Relays Fit in a Control Panel
Functional Devices manufactures the RIB® relay line, which is used across control panel builds.
- For general switching, the RIB2401B is a 20 Amp SPDT relay with a 24 Vac/dc or 120 Vac coil.
- For two independent circuits driven from one signal, the RIB24P is a 20 Amp DPDT relay with a 24 Vac/dc coil and pilot-duty ratings.
- For light-duty switching where control voltage varies across the panel, the RIBU1C is a 10 Amp SPDT relay with a universal 10–30 Vac/dc or 120 Vac coil; the universal coil reduces the number of relay SKUs a panel line has to stock.
For panels built on DIN rail, Functional Devices makes DIN-rail RIB® relays that snap onto 35 mm rail in place of foot-mounted enclosed relays. The RIBRL1S-NS is a UL916-Listed, 10 Amp SPDT DIN-rail relay with a 10–30 Vac/dc coil and a coil-side override switch. DPDT DIN-rail models are also available.
Control Power for a UL508A Control Panel
For 24 Vac, the TR40VA001 is a 40 VA, 120 to 24 Vac transformer with inherent current limiting; the TR75VA001 is a 75 VA, 120 to 24 Vac transformer with a secondary circuit breaker. Where the panel needs a packaged source, the PSH series is an enclosed 24 Vac Class 2 power supply built around one or two transformers, with a breaker and an output LED, in 40, 75, and 100 VA sizes, and the TIB series is a DIN-rail enclosed transformer with an integrated breaker.
For 24 Vdc, the PSM series supplies isolated, regulated 24 Vdc from a 24 Vac input, and PSH models with a -DC suffix (like the PSH100A100AB10-DC) add a switching 24 Vdc output.
Functional Devices transformers and power supplies for 24 V control power are built and listed to Class 2, which allows for the lighter wiring methods a Class 2 circuit permits.
Time Delay and Sequencing in a Control Panel
Where the panel has to stage equipment on start-up or hold a circuit after shutdown, a time delay relay provides a delay-on-make or delay-on-break function in place of external timing logic. Functional Devices manufactures a line of enclosed time delay relays for exactly this purpose, matched to the same coil and contact ratings as the standard RIB® relays. Sequencing built into the panel this way mitigates the need for a timing device that the panel builder would otherwise need to source and wire separately.
Sourcing UL508A Panel Components From One Manufacturer
Sourcing the components for the control side of a panel from one manufacturer means you can easily keep documentation consistent. With Functional Devices, relays, control power, and control panel enclosures can all be sourced together. Components are available through authorized distributors.
Frequently Asked Questions About UL508A Control Panels
Does Functional Devices sell finished UL508A control panels?
No. Functional Devices manufactures the individual UL Listed and UL Recognized components used inside a panel: relays, transformers, power supplies, and enclosures. A UL508A-authorized panel shop assembles, tests, and applies the listing mark to the finished panel.
Are RIB® relays UL Listed for use in a UL508A panel?
RIB® relays carry UL Listing or UL Recognition depending on the model and the standard they are evaluated to. Confirm the designation for the specific SKU on its datasheet before specifying.
Which RIB® relays are used in control panel builds?
Common choices are the RIB2401B for general 20 Amp SPDT switching, the RIB24P for 20 Amp DPDT two-circuit switching, the RIBU1C for light-duty switching with a universal coil, and the DIN-rail RIBRL1S-NS for rail-mounted panels.
Where can I source RIB® components for a panel build?
RIB® relays, transformers, power supplies, and enclosures are sold through authorized Functional Devices distributors.
Ready to Source Control Panel Components?
To source RIB® relays, transformers, power supplies, and enclosures for a UL508A control panel build, find an authorized Functional Devices distributor near you.