Resideo at87a1189/u Nema Type E Transformer 277V

Product Description

The RESIDEO at87a1189/u is a NEMA Type E standard transformer rated for 277-volt primary service, designed for low-voltage HVAC control circuits. It meets NEC Class 2 (non-wet locations) and Class 3 (wet locations) requirements, as well as UL 1585 standards. The unit includes built-in overload protection to guard against fault conditions. Color-coded leadwires on the primary side simplify field wiring and reduce connection errors. Licensed HVAC technicians and commercial electrical contractors are the typical installers for this type of transformer.

This transformer is suited for commercial and light-industrial HVAC applications where a 277-volt primary supply is present, a common voltage on three-phase wye distribution systems in commercial buildings. It is used in control circuits that require a reliable step-down transformer to power thermostats, relays, and other low-voltage devices. The NEMA Type E designation indicates conformance to defined enclosure and performance standards for this class of transformer.

Key Features

• 277-volt primary rating for compatibility with commercial three-phase wye electrical systems
• NEMA Type E designation meets defined enclosure and performance standards
• Meets NEC Class 2 (non-wet) and Class 3 (wet) requirements
• Listed to UL 1585
• Built-in overload protection included
• Color-coded primary leadwires for accurate, efficient field wiring

Compatibility

Designed as an OEM-style replacement or new-installation transformer for commercial HVAC control circuits requiring a 277-volt primary input.

Installation Notes

Installation should be performed by a licensed electrician or HVAC technician in accordance with the NEC and all applicable local codes. Disconnect and lock out all power to the circuit before handling or connecting the transformer. Verify primary voltage at the supply is 277 volts before energizing. Follow the color-coded leadwire markings for correct primary connections and ensure all wire terminations are secure before restoring power.

Technical Specifications

• Primary Voltage: 277 volts
• NEMA Type: E
• NEC Classification: Class 2 (non-wet), Class 3 (wet)
• UL Listing: UL 1585
• Overload Protection: Built-in
• Primary Wiring: Color-coded leadwires

Standard Information

• Brand: RESIDEO
• Manufacturer Part Number: at87a1189/u