SPDT Switches | McMaster-Carr

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	Current Current

	Environment Environment

	Maximum Setpoint Maximum Setpoint

5 in. of H2O

500 fpm

	Switch Type Switch Type	Show

SPDT

	Switch Type Switch Type	Hide

	Specifications Met Specifications Met

CE Marked

CSA

ETL

	For Use Outdoors For Use Outdoors

Yes

	Maximum Voltage Maximum Voltage

	Sensing Type Sensing Type

Paddle

Diaphragm

	For Use With For Use With

	RoHS (Restriction of Hazardous Substances) RoHS (Restriction of Hazardous Substances)

RoHS Compliant

RoHS Compliant with
Exemptions

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	Minimum Setpoint Minimum Setpoint

0.05 in. of H2O

350 fpm

	For Conduit Trade Size For Conduit Trade Size

1/2

	Paddle Material Paddle Material

Stainless Steel

	Paddle Width Paddle Width

3 1/8"

	Electrical Connection Type Electrical Connection Type

Hardwire

Screw Terminal

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	Maximum Temperature Maximum Temperature

Less than 250° F

	Minimum Temperature Minimum Temperature

-99° to 0° F

1° to 99° F

	Environmental Rating Environmental Rating

IP43

IP65

NEC Class I Divisions 1, 2
Group D

NEC Class I Divisions 1, 2
Groups C, D

NEC Class II Divisions 1, 2
Groups E, F, G

	Enclosure Material Enclosure Material

Plastic

Steel

	Temperature Setting Temperature Setting

	Mounting Location Mounting Location

16 Products

Airflow-Actuated HVAC Switches

Use this switch to sense changes in airflow velocity in duct. The paddle extends into the duct and actuates the switch when airflow reaches the setpoint. Switch is rated NEMA 3R for protection from dirt, falling liquids, and light splashing.

							Paddle
Setpoint, fpm	Temperature Range, °F	Current	Electrical Connection Type	Switch Type	For Conduit Trade Size	Knockout Dia.	Material	Ht.	Wd.	For Use Outdoors	Environmental Rating	Specifications Met		Each
Paddle Sensor
350-500	32° to 104°	10 A @ 240 V AC 16 A @ 120 V AC	Screw Terminal	SPDT	1/2	7/8"	Stainless Steel	6 7/8"	3 1/8"	Yes	IP43, NEMA 3R	UL Listed, C-UL Listed, CE Marked	0000000	0000000

Air-Pressure-Actuated HVAC Switches

Often used to detect clogged air filters and iced air conditioner coils, these switches sense small changes in pressure between two points in your duct.

Diaphragm Sensor
Setpoint, in. of H2O	Accuracy, in. of H2O	Temperature Range, °F	Current	Electrical Connection Type	Switch Type	Max. Pressure, psi	Low Pressure Side Connection	High Pressure Side Inside Connection	High Pressure Side Outside Connection		Each
0.05-5	0.025	-40° to 165°	2.9 A @ 240 V AC 5.8 A @ 120 V AC	Hardwire	SPDT	1	1/8 NPT Female	1/8 NPT Female	1/2 NPSM	000000	0000000
0.05-5	0.04	-40° to 165°	4.9 A @ 240 V AC 9.8 A @ 120 V AC	Hardwire	SPDT	1	1/8 NPT Female	1/8 NPT Female	1/2 NPSM	000000	000000

Line-Voltage Thermostats

For Air Conditioners and Heaters

Regulate line-voltage HVAC systems.

				Overall
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Mounting Fasteners Included	Specifications Met		Each
For Air Conditioners and Heaters
24V AC-277V AC	22	40° to 90°	SPDT	4 3/4"	3"	1 3/8"	Yes	UL Listed	0000000	0000000

Multi-Speed Line-Voltage Thermostats

Control one- and two-speed line-voltage HVAC systems. Set the thermostat to activate the device’s second speed when the temperature surpasses the setting for the first speed by 3.6° F to 9° F.

				Overall
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Temp. Differential, °F	For Use Outdoors	Mounting Fasteners Included	Environmental Rating	Specifications Met		Each
For Air Conditioners and Heaters
24V AC-250V AC	15	32° to 140°	SPDT	6"	2 3/4"	3 3/8"	3.6° to 9°	Yes	Yes	IP65; NEMA 4	CE Marked	0000000	0000000

Line-Voltage Thermostats with Thermowell

Commonly used with line-voltage hydronic heaters, this thermostat senses the temperature of liquids. The thermowell protects the sensor.

				Overall			Thermowell
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Thread Type	Pipe Size	Specifications Met		Each
For Air Conditioners and Heaters
120V AC-240V AC	10	100° to 240°	SPDT	4 1/2"	2 1/4"	1 7/8"	NPT	1/2	UL Listed	000000	0000000

DIN-Rail Mount Remote-Sensor Line-Voltage Thermostats

Thermostat

Replacement Sensor and Cable

Place sensor in enclosures or different rooms than the rest of the thermostat to control temperature from outside the space. Thermostat works with line-voltage HVAC systems.

				Overall
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Sensor Cord Lg., ft.	Mounting Fasteners Included	Mounting Hole Dia.	Specifications Met		Each
For Air Conditioners and Heaters
120V AC-240V AC	15	-30° to 212°	SPDT	5"	2 3/8"	2 3/8"	6	No	1/4"	UL Listed	0000000	0000000

Replacement Sensor and Cable

00000000

Each

000000

Remote-Sensor Line-Voltage Thermostats

Place sensor in enclosures or different rooms than the rest of the thermostat to control temperature from outside the space. Thermostats work with line-voltage HVAC systems.

					Overall
	Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Sensor Cord Lg., ft.	Mounting Fasteners Included	Mounting Hole Dia.	Specifications Met		Each
For Air Conditioners and Heaters
A	120V AC-277V AC	22	-30° to 100°	SPDT	5"	2 1/4"	1 5/8"	8	No	1/8"	UL Listed	0000000	0000000
B	120V AC-277V AC	22	40° to 110°	SPDT	5 1/2"	2 1/8"	2 5/8"	2	No	1/8"	UL Listed	0000000	000000

Remote-Sensor Line-Voltage Thermostats with Thermowell

Commonly used with line-voltage hydronic heaters, this thermostat senses the temperature of liquids at a distance using the remote sensor. The thermowell protects the sensor.

				Overall				Thermowell
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Sensor Cord Lg., ft.	Thread Type	Pipe Size	Mounting Fasteners Included	Mounting Hole Dia.	Specifications Met		Each
For Air Conditioners and Heaters
120V AC-240V AC	10	100° to 240°	SPDT	4 1/2"	2 1/4"	1 7/8"	8	NPT	1/2	No	1/4"	UL Listed	000000	0000000

Washdown Line-Voltage Thermostats

These thermostats are rated NEMA 4X for protection from dirt, washdowns, and corrosion. Use to regulate line-voltage HVAC systems.

				Overall
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	For Use Outdoors	Mounting Fasteners Included	Mounting Hole Dia.	Specifications Met	Environmental Rating		Each
For Air Conditioners and Heaters
120V AC-277V AC	22	40° to 100°	SPDT	6 7/8"	3 1/8"	4"	Yes	No	5/32"	ETL Listed	NEMA 4X	0000000	0000000

Hazardous Location Line-Voltage Thermostats

Use to regulate line-voltage HVAC systems where flammable gases, vapors, and dust are present. Thermostats are rated Class I, Divisions 1 and 2, Groups C and D; and Class II, Divisions 1 and 2, Groups E, F, and G.

				Overall
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Mounting Fasteners Included	Mounting Hole Dia.	Specifications Met	Environmental Rating		Each
For Air Conditioners and Heaters
24V AC-277V AC	22	50° to 90°	SPDT	5 3/4"	6 3/8"	5 5/8"	No	1/4"	UL Listed, CSA Certified	NEC Class I Divisions 1, 2 Groups C, D NEC Class II Divisions 1, 2 Groups E, F, G NEMA 7	0000000	0000000

Remote-Sensor Hazardous Location Line-Voltage Thermostats

Place sensor in enclosures or different rooms than the rest of the thermostat to control temperature from outside the space. Use to regulate line-voltage HVAC systems where flammable gases, vapors, and dust are present. Thermostats are rated Class I, Divisions 1 and 2, Group D; and Class II, Divisions 1 and 2, Groups E, F, and G.

				Overall
Voltage	Current, A	Temp. Setting, °F	Switch Type	Ht.	Wd.	Dp.	Sensor Cord Lg., ft.	Mounting Fasteners Included	Mounting Hole Dia.	Specifications Met	Environmental Rating		Each
For Air Conditioners and Heaters
120V AC-277V AC	22	20° to 80°	SPDT	5 7/8"	3"	3 1/4"	6	No	3/8"	UL Listed, CSA Certified	NEC Class I Divisions 1, 2 Group D NEC Class II Divisions 1, 2 Groups E, F, G NEMA 7 NEMA 9	0000000	0000000

Humidistats

For Humidifiers

For Humidifiers and Dehumidifiers

Turn the dial to control humidity equipment.

Humidistats for humidifiers and dehumidifiers mount to a surface-mount outlet box.

					Overall
Voltage	Current	Relative Humidity	Switch Type	Color	Ht.	Wd.	Dp.	Mounting Location	Mounting Fasteners Included		Each
For Humidifiers
24V AC-30V AC	1A	10-75%	SPDT	White	3"	4 3/4"	1 3/4"	Duct, Wall	Yes	0000000	000000
For Humidifiers and Dehumidifiers
120V AC/208V AC/240V AC	6A/3.5A/3A	0-70%	SPDT	Beige	4 3/4"	3"	3"	Outlet Box	Yes	0000000	000000