Check the equipment label or manual for its required output voltage, AC or DC type, and power draw, then compare those requirements with the transformer’s specifications. If powering multiple devices, add their power needs and confirm the transformer’s capacity can support the combined load, while also checking that its wiring and mounting style suit the installation.

Plug-in low-voltage transformers connect to a receptacle, while open-frame models are designed for installation inside compatible equipment or an enclosure and require wired connections. Hardwired transformers connect directly to an existing electrical circuit or system wiring, making them suited to fixed installations such as replacement or system power applications.

Match the transformer’s output voltage and VA capacity to the connected equipment, accounting for the combined load and the equipment’s wiring requirements. Check whether the installation calls for a plug-in, open-frame, or replacement format, and follow the manufacturer’s wiring instructions and applicable electrical codes.

Security, access control, and surveillance systems use step-down AC transformers in plug-in or open-frame formats, with output voltage and VA matched to the connected equipment. Landscape lighting systems use low-voltage transformers to power existing lighting, and some connect through a bridge to enable app-based controls.