White-Rodgers 90-T40F2 Transformer

The White-Rodgers 90-T40F2 Transformer is a robust, foot-mount Class II control transformer engineered for demanding HVACR and industrial motor control applications. This 40VA transformer features a primary tap for 208/240V input and a 24VAC secondary output, providing stable low-voltage power to contactors, thermostats, and ignition modules. Designed for versatility, this model serves as a field-ready replacement for the 620858R; however, please note that while the 620858R typically utilize spade connections, the 90-T40F2 utilizes color-coded wire leads for a permanent, vibration-resistant hardwired install. Its open construction and energy-limiting design ensure it manages momentary short circuits effectively, preventing total system failure during minor electrical transients. For technicians working in tight cabinets, the compact foot-mount footprint and pre-stripped 18 AWG leads streamline the replacement process without requiring additional mounting brackets.

• Universal Compatibility: Efficiently steps down 208V/240V primary voltage to the 24V secondary required for modern HVAC control circuits.
• Direct 620858R Replacement: Corrects common system power issues by replacing failed 4021F and 620858R units (verify lead-to-spade conversion).
• Class 2 Safety Rated: Inherently energy-limiting design reduces fire risk and protects sensitive downstream control boards.
• Contractor-Grade Durability: Capable of operating in ambient temperatures up to 150°F, ideal for furnace interiors and rooftop units.

Common Questions

Can I use this to replace a transformer with spade terminals?
Yes, the White-Rodgers 90-T40F2 is the standard replacement for the 620858R. You will simply need to transition from spade connectors to wire leads using appropriate wire nuts or crimp connectors.

What happens if there is a short in my 24V circuit?
As a Class II energy-limiting transformer, it is designed to handle momentary shorts. However, a sustained secondary short will eventually cause the internal winding to open to prevent a fire hazard.

Is this unit compatible with 120V systems?
No, this specific model is rated for 208/240V primary input only. Wiring a 120V source to this transformer will result in insufficient secondary voltage (approx. 12V), which will not pull in contactors.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.