Resideo 1321-1 16.5 VAC 25 VA Alarm Transformer

Resideo 1321-1 Class 2 Plug-In Transformer

The Resideo 1321-1 converts standard 120 VAC power to 16.5 VAC at 25 VA for compatible security alarm control panels. It is suitable for new installations or direct replacement where the manufacturer specifies this exact voltage and capacity.

Specifications

• Input: 120 VAC, 60 Hz
• Output: 16.5 VAC, 25 VA
• Plug-in Class 2 transformer
• UL listed
• Model: 1321-1

Compatibility note: Match both output voltage and VA rating to the control panel documentation. Disconnect power before wiring, secure the transformer as required, and use professional installation where applicable.

Selection: This is an AC transformer, not a 12 VDC power adapter. The manufacturer’s VISTA-15P/20P installation guide specifies the 1321 transformer family at 16.5 VAC, 25 VA. Confirm the exact 1321-1 replacement against your panel documentation and the transformer label; do not select it by voltage alone.

Manufacturer documentation: Resideo VISTA-15P/20P Installation and Setup Guide K5305-1V10C, sections 2-3 and 5-1–5-2 (manufacturer-authored manual hosted by Alarm Grid).