Choosing an Electrical Switch
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Hinge-Actuated Safety Switches
Replace access door hinges with these switches; they actuate when the door opens at least 4°. Also known as interlock switches, they ensure the safety of personnel by automatically shutting off power to machinery when an access door opens. All have positive-force, normally-closed contacts that will open a circuit when the switch is actuated even if a spring fails or the contacts stick. In addition to access doors, these switches can also be used on machine guards constructed from aluminum T-slotted framing. They’re rated IP65 for protection from washdowns.
For technical drawings and 3-D models, click on a part number.
Overall | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. of Circuits Controlled | Switch Starting Position | Switch Action | No. of Terminals | Industry Designation | Switching Current @ Voltage | Wire Connection Type | Conduit Thread Size  | Ht. | Wd. | Dp. | Each | |
| 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Springs Back (Momentary) | 6 | 3PST-1NO/2NC | 2 A @ 250 V AC | Screw Terminals | M20 | 3.62" | 4.39" | 1.42" | 0000000 | 0000000 |
Frame-Mounted Safety Switches
Also known as interlock switches, these ensure the safety of personnel by automatically shutting off power to machinery when an access door opens. Mount the switch to the door frame and mount a key to the door so that the key is inserted into the switch when the door is closed. When the door opens, the key is removed from the switch and the machine shuts down. They’re often used with machine guards.
Style A-F have positive-force, normally closed contacts that will open a circuit when the switch is actuated even if a spring fails or the contacts stick.
IP67 rated switches protect against temporary submersion.
Flexible keys (sold separately) pivot 15° to make it easier to align with the switch during installation.
For technical drawings and 3-D models, click on a part number.
Housing | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Style | No. of Circuits Controlled | Switch Starting Position | Switch Action | No. of Terminals | Industry Designation | Switching Current @ Voltage | Max. Voltage | Ht. | Wd. | Dp. | Conduit Trade Size | Conduit Thread Size | Key Included | Environmental Rating | Each | |
Screw Terminal Connection with Positive-Force Normally Closed Contacts | ||||||||||||||||
| C | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 3 | 3PST-1NO/2NC | 8 A @ 120 V AC, 4 A @ 24 V DC | 250V DC 600V AC | 3.5" | 2.1" | 1.2" | 1/2 | __ | Yes | IP67 | 00000000 | 0000000 |
| C | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 6 | 3PST-1NO/2NC | 4 A @ 230 V AC, 4 A @ 24 V DC | 24V DC 500V AC | 3.5" | 2" | 1.2" | __ | M16 | Yes | IP67 | 00000000 | 000000 |
| D | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 6 | 3PST-1NO/2NC | 6 A @ 120 V AC, 0.27 A @ 24 V DC | 240V AC 250V DC | 3.8" | 1.2" | 1.2" | 1/2 | __ | Yes | IP67 | 00000000 | 000000 |
Screw Terminal Connection with Positive-Force Normally Closed Contacts and Rotating Head | ||||||||||||||||
| C | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 6 | 3PST-1NO/2NC | 5 A @ 120 V AC, 5 A @ 24 V DC | 400V DC 400V AC | 3.5" | 2" | 1.299" | 1/2 | __ | Yes | IP65 | 00000000 | 000000 |
| D | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 6 | 3PST-1NO/2NC | 10 A @ 120 V AC, 2.5 A @ 125 V DC | 240V AC 250V DC | 3.8" | 1.2" | 1.2" | __ | M20 | No | IP67 | 00000000 | 00000 |
| F | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 6 | 3PST-1NO/2NC | 10 A @ 230 V AC, 4 A @ 24 V DC | 24V DC 250V AC | 4.3" | 1.6" | 1.4" | __ | M20 | No | IP67 | 00000000 | 000000 |
Access-Delay Frame-Mounted Safety Switches
Delay access to hazardous areas until conditions are safe; use these switches with machines that take time to stop after they are turned off. Mount the switch to the door frame and mount the key to the door so that the key is inserted into the switch when the door is closed. When the door is pulled, the key is held in place with 225 lbs. of force until the switch receives a signal from a time-delay relay, motion sensor, or position sensor (not included) that the machine’s motion has stopped. After the motion has stopped, the key can be removed from the switch, releasing the access door. They’re often used with machine guards. All have positive-force, normally-closed contacts that will open a circuit when the switch is actuated even if a spring fails or the contacts stick. They’re rated for protection from washdowns and temporary submersion.
Style A and B have a key entry on the top and side of the switch.
Emergency override keys (sold separately) bypass the access delay feature.
For technical drawings and 3-D models, click on a part number.
Housing | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Style | No. of Circuits Controlled | Switch Starting Position | Switch Action | No. of Terminals | Industry Designation | Switching Current @ Voltage | Max. Voltage | Input Voltage | Holding Force, lbs. | Ht. | Wd. | Dp. | Wire Connection Type | Conduit Trade Size | Each | |
Positive-Force Normally Closed Contacts | ||||||||||||||||
| A | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 6 | 3PST-1NO/2NC | 5 A @ 120 V AC, 2 A @ 24 V DC | 500V AC 250V DC | 24V AC, 24V DC | 225 | 4.7" | 2.3" | 1.4" | Screw Terminals | 1/2 | 0000000 | 0000000 |
| A | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 6 | 3PST-1NO/2NC | 5 A @ 120 V AC, 2 A @ 24 V DC | 500V AC 250V DC | 110V AC | 225 | 4.7" | 2.3" | 1.4" | Screw Terminals | 1/2 | 0000000 | 000000 |
| B | 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | Stays Switched (Maintained) | 14 | 3PST-1NO/2NC | 3 A @ 120 V AC, 2.5 A @ 24 V DC | 250V DC 240V AC | 24V DC | 225 | 3.7" | 3.5" | 1.4" | Screw Terminals | 1/2 | 0000000 | 000000 |
| Emergency Override Key for Style A | 0000000 | Each | 000000 |
Tamper-Resistant Magnetically Actuated Switches
Prevent unauthorized use—these switches require coded magnets (sold separately) to actuate, and cannot be bypassed using ordinary magnets. They actuate when a magnet comes within sensing distance, and reset when the magnet moves away. Mount the switch in a stationary position, such as a door frame, and mount the magnet to a movable object, such as the door. They’re often used to detect when a door or window opens, and can be used with movable machine guards. All are rated IP67 for protection from temporary submersion.
Coded magnets include tamper-resistant one-way screws for mounting. To remove screws, see one-way bits and drivers.
Safety relays are required in safety applications with switches that control two or three circuits.
For technical drawings and 3-D models, click on a part number.
Switches | Coded Magnets | Safety Relays | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. of Circuits Controlled | Switch Starting Position | Industry Designation | Switching Current @ Voltage | Max. Voltage | Input Voltage | Max. Sensing Distance | Lg. | Wd. | Ht. | Environmental Rating | Each | Each | Each | |||
Plastic Housing with Wire Leads | ||||||||||||||||
| 3 | 1 Off (Normally Open) and 2 On (Normally Closed) | 3PST-1NO/2NC | 10 mA @ 24 V DC | 24V DC | 24V DC | 0.2" | 3.5" | 1" | 0.5" | IP67 | 0000000 | 0000000 | 0000000 | 000000 | 0000000 | 0000000 |