System of Measurement System of Measurement |
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Switching Current Switching Current | Show |
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Switching Current Switching Current | Hide |
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Wire Connection Type Wire Connection Type |
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Quick- Disconnect Terminals | Screw Terminals |
For Use With For Use With |
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Power Power |
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Switch Starting Position Switch Starting Position |
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Pipe Size Pipe Size |
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DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense AcquisitionRegulations Supplement) |
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Mounting Location Mounting Location |
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Operates On Operates On |
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Operation Type Operation Type |
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About Relays
More
About Pressure Switches
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Infrequent-Cycle High-Current Relays



For use with equipment that cycles on and off, these relays meet UL 508 for air conditioning and heating. Connections are accessible from the front, so you can mount relays side-by-side. Also known as definite-purpose contactors.
Enclosures (sold separately) are NEMA 1 rated to protect contacts from corrosion.
Also Available: Auxiliary contacts for 3.8"-7.2" Ht. relays. They allow you to add a signaling device or control another relay. Please select 6564K99, then select the McMaster-Carr part number of your relay and whether you want to switch one circuit on (1 Normally Open) or off (1 Normally Closed).
For technical drawings and 3-D models, click on a part number.
Switching Current @ 600V AC | hp @ Switching Voltage | ||||||||||||
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Number of Terminals | Input Voltage | Control Power | Full Load | Resistive Load | Single Phase | Three Phase | Ht. | Wd. | Dp. | Quick-Disconnect Tab Wd. | Specifications Met | Each | |
2 Circuits Controlled with 2 Off (Normally Open)—DPST-NO | |||||||||||||
With Quick-Disconnect and Screw Terminals | |||||||||||||
4 | 24V AC | 6.5VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | __ | 3.2" | 2" | 2.3" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 000000 |
4 | 120V AC | 6.5VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | __ | 3.2" | 2" | 2.3" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 00000 |
4 | 24V DC | 3.1W | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | __ | 3.8" | 2.4" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 000000 |
4 | 208/240V AC | 6.5VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | __ | 3.2" | 2" | 2.3" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 00000 |
3 Circuits Controlled with 3 Off (Normally Open)—3PST-NO | |||||||||||||
With Quick-Disconnect and Screw Terminals | |||||||||||||
6 | 24V AC | 7VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.4" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 00000 |
6 | 120V AC | 7VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.4" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 00000 |
6 | 24V DC | 3.1W | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.4" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 000000 |
6 | 208/240V AC | 7VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.4" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 00000 |
4 Circuits Controlled with 4 Off (Normally Open)—4PST-NO | |||||||||||||
With Quick-Disconnect and Screw Terminals | |||||||||||||
8 | 24V AC | 50.4VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.7" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 000000 |
8 | 120V AC | 50.4VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.7" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 000000 |
8 | 24V DC | 5.1W | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.7" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 000000 |
8 | 208/240V AC | 50.4VA | 25A | 35A | 2 hp @ 115 V AC 3 hp @ 230 V AC | 7 1/2 hp @ 230 V AC 10 hp @ 460 V AC 10 hp @ 575 V AC | 3.8" | 2.7" | 3.4" | 0.25" | UL Recognized Component, CSA Certified, CE Marked, UL 508 | 00000000 | 000000 |
Enclosures for 60A 3PST-NO Relays and 4PST-NO Relays | 00000000 | Each | 0000000 |
Medium-Current Relays

Use these relays with industrial automation systems, security and emergency lighting, and small motors. Also known as power relays.
Optional covers protect contacts from dust and dirt.
Relays | |||||||||||||
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Switching Current | Optional Covers | ||||||||||||
Number of Terminals | Input Voltage | Control Current, mA | @ 120V AC | @ 28V DC | hp @ Switching Voltage | Ht. | Wd. | Dp. | Specifications Met | Each | Each | ||
4 Circuits Controlled with 4 Off (Normally Open) or 4 On (Normally Closed)—4PDT | |||||||||||||
14 | 120V AC | 116 | 35A | 20A | 1 1/2 hp @ 240 V AC 1 hp @ 120 V AC | 3.4" | 2.7" | 2.7" | UL Listed C-UL Listed | 0000000 | 0000000 | 0000000 | 000000 |
Medium-Pressure Switches for Air Compressors


- For Use With: Air
- Connection Material: Steel
- Connection: NPT Female
- Switching Current:
Polycarbonate Plastic: 24/24A
Steel Housing: 35/24A - Switching Voltage: 120V AC/240V AC
These switches meet pressure and electrical requirements of air compressors. They electrically activate automated controls or alarms when a set pressure is reached. Switches are double pole, single throw and normally closed (DPST-NC), so they switch two circuits from on to off.
Switches with air exhaust valve let you release the compressed air after use.
Temperature Range, °F | Conduit | |||||||||||
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Setpoint, psi | Approximate Difference Between Setpoint and Reset Point, psi | Max. Pressure, psi | Accuracy | Pipe Size | Environment | Process | For Trade Size | Connection Gender | Ht. | Specifications Met | Each | |
Switches | ||||||||||||
Steel Housing | ||||||||||||
10-125 | 27 | 300 | ±5% | 3/8 | -30° to 160° | -30° to 210° | 1/2 | Female | 4 1/16" | CSA Certified, UL Listed | 00000000 | 0000000 |
40-250 | 47 | 300 | ±5% | 3/8 | -30° to 160° | -30° to 210° | 1/2 | Female | 4 1/16" | CSA Certified, UL Listed | 00000000 | 000000 |
Switches with Air Exhaust Valve | ||||||||||||
Steel Housing | ||||||||||||
10-125 | 27 | 300 | ±5% | 3/8 | -30° to 160° | -30° to 210° | 1/2 | Female | 4 1/16" | CSA Certified, UL Listed | 00000000 | 000000 |
40-250 | 47 | 300 | ±5% | 3/8 | -30° to 160° | -30° to 210° | 1/2 | Female | 4 1/16" | CSA Certified, UL Listed | 00000000 | 000000 |