Name: Resideo AT150B1252/U Foot Mounted 277 Vac Transformer with 9 in Leadwires and Plastic End Caps
Brand: Resideo
SKU: HONE-AT150B1252/U
Price: 50.34 USD
Availability: InStock

Foot mounted 277 Vac Transformer with 9 in leadwires and plastic end caps

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Frequency	50 Hz; 60 Hz
Electrical Ratings	Primary voltage--277 Vac; Secondary voltage--27.5 V.O.C.
Mounting	Foot-mounted
Includes	Plastic end caps
Dimensions	1 11/16 in. high x 3 1/2 in. wide x 1 3/4 in. deep
UL	UL Component Recognized: B, D, E models. File# E14881
CSA	CSA Certified: A & B models.
Temperature Range (F)	-20 F to +105 F
Electrical Connections (Primary)(in.)	9 in. leadwires with 1/4 in. male quick-connects
Electrical Connections (Secondary)(in.)	9 in. leadwires with 1/4 in. male quick-connects with plastic (2) end covers
Electrical Ratings, Output	24 Vac at 50 VA

The AT150B1252 is a control transformer from Resideo (Honeywell Home), 150 VA, 277 V primary, foot mount.

Almost every heating and cooling control runs on 24 volts, and the transformer is what makes it. It takes line voltage in and delivers the low-voltage supply that the thermostat, the zone valves, the relays and the gas valve all share.

Size it by VA, not by voltage. VA is the load the transformer can carry, and every device on the control circuit adds to it — a zone valve pulls current while it drives, a relay coil holds current the whole time it is energized, and a Wi-Fi thermostat draws continuously. A transformer sized for the original equipment will not carry the same system after two zones and a smart stat have been added, and the symptom is intermittent: things work alone and fail together.

Mounting matters more than it looks. The transformer has to land where the enclosure has room and where the leads reach, and a foot-mount body will not sit in a knockout that was made for a plate mount.

Leadwires are 9 inches.

Brand: Resideo (Honeywell Home)
Manufacturer Part #: AT150B1252/U
Type: Control transformer
Rating: 150 VA
Primary: 277 V
Secondary: 24 Vac
Mounting: Foot
Leadwires: 9 in
UPC: 085267150255
Category: Transformers

Full Specifications

NEMA Rating	No
Primary Connection Size	9 in, 229 mm
Primary Connection Type	Leadwires with stripped ends: Black and Brown
Primary Input Voltage	277 V ac
Secondary Connection Size	9 in, 229 mm
Secondary Connection Type	Leadwires with 1/4 in. male quick-connects with plastic (2) end covers
Secondary Open Circuit Voltage	27.5 V.O.C.
VA Rating	50 VA
Frequency	50 Hz; 60 Hz
Approvals and Standards	UL Component Recognized: B, D, E models. File# E14881, CSA Certified: A & B models, NEC Class 2
Includes	Plastic end caps
Ambient Operating Temperature (Max)	105 °F, 41 °C
Ambient Operating Temperature (Min)	-20 °F, -29 °C
Product Height	1.69 in, 43 mm
Product Width	3.5 in, 89 mm