Sentry 300 550012 Photo Eye Kit Overview
The Sentry 300 550012 photo eye kit creates an infrared beam between two units. When the beam is interrupted, the gate control board can stop the closing cycle or keep the gate from closing, depending on the wiring and operator settings. It is used as part of the safety layout on compatible Sentry 300 swing gate systems and is especially important where vehicles, people, animals, or objects may enter the gate path.
Photo eyes are not selected only by brand name. The installer must confirm the wiring method, available accessory power, switch settings, required monitored safety inputs, and physical beam placement. The Sentry documentation describes wired connections to both units and notes that a typical swing gate may need two sets for better protection.
Compatible With
Use this kit with compatible Sentry 300 control boards and swing gate layouts that support this wired photo eye arrangement.
- Sentry 300 swing gate opener systems using the 550012 photo eye accessory
- Sentry 300S single swing gate installations requiring photo beam protection
- Sentry 300D dual swing gate installations requiring photo beam protection
- Compatible Sentry/USAutomatic 12 VDC accessory wiring points when installed according to the manual
- Driveway gate entrance and open-position protection zones, depending on gate layout
- Not a replacement for unrelated monitored photo eyes unless the control board and safety requirements match
Features and Specifications
| Manufacturer | USAutomatic / Sentry |
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| Product Type | Photo eye safety beam kit |
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| Part Number | 550012 |
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| Application | Secondary safety device for compatible swing gate openers |
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| Wiring | Wired transmitter and wired receiver; 20 gauge wire commonly referenced |
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| Beam Distance | Up to 40 ft in Sentry manual application notes; actual range depends on alignment and site conditions |
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| Function | Interrupted beam can stop or prevent closing when wired and configured correctly |
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| Mounting | Transmitter and receiver must face each other at matching height |
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| Safety Monitoring | Verify current operator and UL 325 requirements before using as a replacement |
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| Notes | Control-board switch and input wiring must match the Sentry instructions |
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Also Known As / Related Part Numbers
- 550012
- US-550012
- Sentry 550012
- Sentry 300 550012
- USAutomatic 550012
- US Automatic 550012
- Sentry photo eye kit
- Sentry photo beam kit
- Sentry safety sensor kit
- wired photo eye for Sentry 300
Technician Note
If the gate will not close, check beam alignment, dirty lenses, damaged wire, water intrusion, switch settings, and input wiring before replacing the photo eye kit. A broken beam or miswired receiver can look like a control-board issue.
Before Ordering Checklist
- Confirm the existing system uses Sentry 550012 style photo eyes.
- Verify whether one or two photo eye sets are required for the gate layout.
- Check wire route, conduit, junction box, and available conductors.
- Confirm transmitter and receiver face each other and are mounted where the gate will not break the beam.
- Never bypass photo eyes to make a gate close.
Professional Advisory
Gate safety device installation and testing should be handled carefully. If the gate is missing required entrapment protection or fails safety testing, have a qualified gate technician inspect the system.
Product Questions
What does the Sentry 300 550012 photo eye kit do?
It creates a beam between the transmitter and receiver. When the beam is broken, the compatible gate operator can stop or prevent closing.
Does a swing gate need one set or two sets of photo eyes?
It depends on the gate layout and hazard areas. Sentry documentation notes that a typical swing gate may need two sets for better area protection.
Can I bypass the photo eye if the gate will not close?
No. Do not bypass required safety devices. Troubleshoot alignment, wiring, power, and control-board settings instead.
How far apart can the photo eyes be mounted?
Sentry manual application notes reference a maximum distance of about 40 ft for the 550012 setup. Actual performance depends on alignment and site conditions.
Why does my gate stop or refuse to close after installing photo eyes?
Common causes include reversed or loose wires, misalignment, dirty lenses, wrong switch setting, blocked beam, low power, or using the wrong safety device for the control board.