Thermal Relays | McMaster-Carr

	Power Power

1/2hp

3/4hp

1hp

	Overload Current Range Overload Current Range

	Component Component

Switch

Thermal Overload Element

	Input Voltage Input Voltage

	Electrical Phase Electrical Phase

Single

Three

	Input Electrical Phase Input Electrical Phase

Three

Single

	Output Voltage Output Voltage

	Number of Circuits Controlled Number of Circuits Controlled

	Environmental Rating Environmental Rating

	Current Current

	Power-Indicating Light Power-Indicating Light

Without Power-Indicating
Light

With Power-Indicating Light

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

DFARS Specialty Metals
COTS-Exempt

	Reversing Capability Reversing Capability

Nonreversing

Reversing

	Depth Depth

	Width Width

	Environment Environment

	Mounting Location Mounting Location

DIN Rail

Surface

	Height Height

	Housing Material Housing Material

Plastic

Steel

Zinc

	Housing Color Housing Color

	Gray		Black
	Beige		Clear
	White

	Number of Mounting Holes Number of Mounting Holes

	Mounting Hole Diameter Mounting Hole Diameter

	Maximum Output Frequency Maximum Output Frequency

120 Hz

320 Hz

500 Hz

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53 Products

About Motor Switches and Starters

Switch with Power
Indicating Light
and Steel Wall Plate

Switch with
Power Indicating
Light and Steel Housing

Switch withSteel Wall Plate

Switch with Steel Housing

Switch with Zinc Housing

Assemble your own motor starter by combining a switch and a thermal overload element.

NEMA 4 and 12 rated switches are protected from washdowns and oil/coolant dripping.

Thermal overload elements shut motors off if current exceeds the full-load current rating. To Order: Please specify the full-load current rating of your motor. If the full-load current rating is not shown on the motor’s faceplate, estimate the current rating (given the motor’s horsepower and voltage).

With Power-Indicating Light
No. of Circuits Controlled	Electrical Phase (hp)	Ht.	Wd.	Wire Connection Type	Environment	Environmental Rating		Each
Steel Wall Plate
1	Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	4.5"	2.8"	Screw Terminals	Indoor	__	0000000	000000
2	Single (3/4 hp @ 115 V DC) Single (3/4 hp @ 230 V DC) Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	4.5"	2.8"	Screw Terminals	Indoor	__	0000000	00000
Steel Housing
1	Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	4.3"	2.8"	Screw Terminals	Indoor	NEMA 1	0000000	00000
2	Single (3/4 hp @ 115 V DC) Single (3/4 hp @ 230 V DC) Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	4.3"	2.8"	Screw Terminals	Indoor	NEMA 1	0000000	000000
Without Power-Indicating Light
Steel Wall Plate
1	Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	4.5"	2.8"	Screw Terminals	Indoor	__	0000000	00000
Steel Housing
1	Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	4.3"	2.8"	Screw Terminals	Indoor	NEMA 1	0000000	00000
2	Single (3/4 hp @ 115 V DC) Single (3/4 hp @ 230 V DC) Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	4.3"	2.8"	Screw Terminals	Indoor	NEMA 1	0000000	00000
Zinc Housing
1	Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	5.5"	3.6"	Screw Terminals	Oily, Washdown	NEMA 4, NEMA 12	0000000	000000
2	Single (3/4 hp @ 115 V DC) Single (3/4 hp @ 230 V DC) Single (1 hp @ 115 V AC) Single (1 hp @ 230 V AC)	5.5"	3.6"	Screw Terminals	Oily, Washdown	NEMA 4, NEMA 12	0000000	000000

Thermal Overload Elements

Overload Current Range		Each
0.157-0.321A	0000000	000000
0.322-0.65A	0000000	00000
0.72-1.25A	0000000	00000
1.3-2.15A	0000000	00000
2.16-4.23A	0000000	00000
4.33-8.98A	0000000	00000
8.99-16A	0000000	00000

Heavy Duty Build-Your-Own Manual Motor Starters

Combine a switch and a thermal overload element to build a starter that can handle high-current-rated motors. They’re also known as NEMA starters.

Thermal overload elements shut motors off if current exceeds the full-load current rating. Three elements are required. To Order: Please specify the full-load current rating of your motor. If the full-load current rating is not shown on the motor’s faceplate, estimate the current rating (given the motor’s horsepower and voltage).

For technical drawings and 3-D models, click on a part number.

Motor Starters

NEMA Contact Size	Electrical Phase (hp)	Ht.	Wd.	Wire Connection Type		Each
M0	Three (2 hp @ 115 V AC) Three (3 hp @ 230 V AC) Three (5 hp @ 460 V AC)	5.8"	3.2"	Screw Terminals	0000000	0000000
M1	Three (3 hp @ 115 V AC) Three (7 1/2 hp @ 230 V AC) Three (10 hp @ 460 V AC)	5.8"	3.2"	Screw Terminals	0000000	000000

Thermal Overload Elements

		Each
	000000	000000

Enclosed Heavy Duty Build-Your-Own Manual Motor Starters

Combine a switch with a thermal overload element to build a starter that can handle high-current-rated motors. All are housed in a durable steel enclosure. They’re also known as NEMA starters.

NEMA 12 rated switches are protected from oil/coolant dripping.

For technical drawings and 3-D models, click on a part number.

Switch with NEMA 1 Enclosure

Switch with NEMA 12 Enclosure

NEMA 1 Motor Starters
NEMA Contact Size	Electrical Phase (hp)	Housing Material	Ht.	Wd.	Dp.	Wire Connection Type	Environment	Environmental Rating	Specifications Met		Each
M0	Three (2 hp @ 115 V AC) Three (3 hp @ 230 V AC) Three (5 hp @ 460 V AC)	Painted Steel	7.6"	4.7"	5"	Screw Terminals	__	NEMA 1	UL Listed, CSA Certified	0000000	0000000
M1	Three (3 hp @ 115 V AC) Three (7 1/2 hp @ 230 V AC) Three (10 hp @ 460 V AC)	Painted Steel	7.6"	4.7"	5"	Screw Terminals	__	NEMA 1	UL Listed, CSA Certified	0000000	000000
NEMA 12 Motor Starters
M0	Three (2 hp @ 115 V AC) Three (3 hp @ 230 V AC) Three (5 hp @ 460 V AC)	Painted Steel	9.4"	5.5"	5"	Screw Terminals	Oily	NEMA 12	UL Listed, CSA Certified	0000000	000000
M1	Three (3 hp @ 115 V AC) Three (7 1/2 hp @ 230 V AC) Three (10 hp @ 460 V AC)	Painted Steel	9.4"	5.5"	5"	Screw Terminals	Oily	NEMA 12	UL Listed, CSA Certified	0000000	000000

Thermal Overload Elements

		Each
	000000	000000

DIN-Rail Mount Programmable Three-Phase AC Motor Speed Controls

Mount these controls to DIN rail inside a control panel. Set them to automatically adjust motor speed. Wire a potentiometer (not included) for remote manual control.

For technical drawings and 3-D models, click on a part number.

			Output		Input Signal
Horsepower, hp	Input Voltage	Current, A	Voltage	Frequency, Hz	Voltage	Current, mA	Ht.	Wd.	Reversing Capability	For DIN Rail Ht., mm	Specifications Met		Each
Single-Phase Input
1/2	100-120V AC	2.4	230V AC	0-320	0-10V DC	4-20	7.68"	3.54"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	0000000
3/4	200-240V AC	2.8	230V AC	0-320	0-10V DC	4-20	6.3"	2.6"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
1	100-120V AC	3.7	230V AC	0-320	0-10V DC	4-20	7.68"	3.54"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
1 1/2	100-120V AC	4.8	230V AC	0-320	0-10V DC	4-20	9.96"	3.94"	Reversing	35	UL Listed CE Marked	0000000	000000
2	200-240V AC	7	230V AC	0-320	0-10V DC	4-20	7.68"	3.54"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
3	200-240V AC	9.6	230V AC	0-320	0-10V DC	4-20	9.96"	3.94"	Reversing	35	UL Listed CE Marked	0000000	000000
Three-Phase Input
3/4	200-240V AC	2.8	230V AC	0-320	0-10V DC	4-20	6.3"	2.6"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
1	200-240V AC	3.7	230V AC	0-320	0-10V DC	4-20	7.68"	3.54"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
1	380-480V AC	2.4	460V AC	0-320	0-10V DC	4-20	6.3"	2.6"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
2	200-240V AC	7	230V AC	0-320	0-10V DC	4-20	7.68"	3.54"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
3	200-240V AC	11	230V AC	0-320	0-10V DC	4-20	9.96"	3.94"	Reversing	35	UL Listed CE Marked	0000000	000000
3	380-480V AC	5.6	460V AC	0-320	0-10V DC	4-20	7.68"	3.54"	Reversing	35	UL Listed C-UL Listed CE Marked	0000000	000000
5	380-480V AC	9	460V AC	0-320	0-10V DC	4-20	9.96"	3.94"	Reversing	35	UL Listed CE Marked	0000000	00000000
7 1/2	380-480V AC	12	460V AC	0-320	0-10V DC	4-20	9.96"	3.94"	Reversing	35	UL Listed CE Marked	0000000	00000000

Programmable Three-Phase AC Motor Speed Controls

Set these controls to automatically adjust motor speed. Wire a potentiometer (not included) for remote manual control.

For technical drawings and 3-D models, click on a part number.

			Output		Input Signal
Horsepower, hp	Input Voltage	Current, A	Voltage	Frequency, Hz	Voltage	Current, mA	Ht.	Wd.	Mounting Fasteners Included	Mounting Hole Diameter (No. of)	Environmental Rating	Specifications Met		Each
Single-Phase Input
Reversing
1	115V AC/230V AC	4	230V AC	0-120	0-10V DC	4-20	7.5"	6.12"	Yes	0.2" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	0000000
1	115V AC/230V AC	4.2	0-230V AC	0-500	0-10V DC	4-20	7.5"	3.9"	No	0.22" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
1 1/2	115V AC/230V AC	5.2	230V AC	0-120	0-10V DC	4-20	7.5"	3.9"	Yes	0.2" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
2	200-240V AC	7	0-230V AC	0-500	0-10V DC	4-20	7.5"	3.9"	No	0.22" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
3	200-240V AC	9.6	0-230V AC	0-500	0-10V DC	4-20	7.5"	3.9"	No	0.22" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
Three-Phase Input
Reversing
1	200-240V AC	4.2	0-230V AC	0-500	0-10V DC	4-20	7.5"	3.9"	No	0.22" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
1	400-480V AC	2	400-480V AC	0-120	0-10V DC	4-20	7.5"	3.89"	No	0.21" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
2	170-264V AC	7	0-230V AC	0-500	0-10V DC	4-20	7.5"	3.89"	No	0.22" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
3	200-240V AC	9.6	0-230V AC	0-500	0-10V DC	4-20	7.5"	3.9"	No	0.22" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
3	200-240V AC	9.6	200-240V AC	0-120	0-10V DC	4-20	7.5"	6.12"	Yes	0.2" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000
5	200-240V AC	18	200-240V AC	0-500	0-10V DC	4-20	10.75"	5.08"	No	0.24" (4)	__	UL Listed C-UL Listed CE Marked	0000000	00000000
5	400-480V AC	8.2	400-480V AC	0-500	0-10V DC	4-20	7.5"	3.9"	No	0.22" (4)	NEMA 1, IP31	UL Listed C-UL Listed CE Marked	0000000	000000

Washdown Programmable Three-Phase AC Motor Speed Controls

Rated NEMA 4, these controls are protected from washdowns. Set them to automatically adjust motor speed. Wire a potentiometer (not included) for remote manual control.

Controls rated NEMA 12 also protect against splashes of oil and coolant when used indoors.

For technical drawings and 3-D models, click on a part number.

			Output		Input Signal
Horsepower, hp	Input Voltage	Current, A	Voltage	Frequency, Hz	Voltage	Current, mA	Ht.	Wd.	Reversing Capability	Environmental Rating	Specifications Met		Each
Single-Phase Input
1	200-240V AC	4.2	200V AC-240V AC	0-120	0-10V DC	4-20	8"	6.5"	Reversing	NEMA 4, NEMA 12, IP65	UL Listed C-UL Listed CE Marked	0000000	0000000
Three-Phase Input
2	200-240V AC	6.8	200V AC-240V AC	0-120	0-10V DC	4-20	7.9"	8.24"	Reversing	NEMA 4, NEMA 12, IP65	UL Listed C-UL Listed CE Marked	0000000	000000
2	400-480V AC	3.4	400V AC-480V AC	0-500	0-10V DC	4-20	8"	6.28"	Reversing	NEMA 4, IP65	UL Listed C-UL Listed CE Marked	0000000	000000
3	400-480V AC	4.8	400V AC-480V AC	0-500	0-10V DC	4-20	8"	6.28"	Reversing	NEMA 4, IP65	UL Listed C-UL Listed CE Marked	0000000	00000000