Residential Slide Gate on a Slope with a Missing Photoeye Pair
You are commissioning a 12 ft (3.7 m) cantilever slide gate on a residential driveway that slopes 4% along the travel path. The operator is a 1/2 HP electromechanical unit rated for a 16 ft gate and 1,200 lb. A single monitored photoeye pair is mounted 8 in (203 mm) above grade on the post at the open limit, aimed across the driveway. The close photoeye is not installed and there is no other entrapment protection on the closing side. The homeowner wants the gate to close automatically after 30 seconds using a timer-to-close. During your first manual test the gate reverses only when the obstruction is within 6 in of the close limit. The homeowner says a neighbor's gate 'closes on a timer with no sensors' and asks you to skip the second photoeye to finish today.
1. Evaluate whether the proposed single-photoeye, timer-to-close configuration can be commissioned as-is, and identify the specific nonconformities.
Read the worked answer
No. Two separate problems exist.
- Entrapment protection on the closing side. A residential slide gate with automatic (timer) closing requires a means of entrapment protection that senses an obstruction in the path of the closing gate. One photoeye pair placed at the open limit and aimed across the driveway does not protect the closing path along the gate's travel. The closing side needs its own monitored photoeye(s) positioned to cover the full travel, plus a means to detect a person trapped between the gate and the close post.
- Reversal test failure. Reversal only within 6 in of the close limit indicates the inherent (built-in) obstruction sensitivity is set too high or the operator is being driven into a mechanical bind on the 4% slope. That must be corrected and re-tested across the full travel.
The neighbor's installation is not a precedent; it is either noncompliant or has protection you cannot see. Decline to bypass, document the deficiency in writing, and offer a compliant scope: second monitored photoeye pair covering the closing path, edge sensor at the close post if required by the operator's listing, corrected sensitivity, and a signed acknowledgment if the homeowner declines automatic closing (manual/constant-pressure only).
2. The slope causes the gate to coast past the open limit switch on the 4% grade. What adjustment approach is appropriate, and what must be re-verified afterward?
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Treat the coast as a control/mechanical issue, not a sensitivity workaround.
- Verify the open limit is set with adequate margin and that the operator's deceleration/soft-stop (if provided) is enabled so the gate is not carried into the stop at full speed.
- Check that the cantilever track and rollers are level and that the gate is not binding; a 4% grade means gravity assists one direction, so the drive must control both directions.
- Confirm the operator is rated for the actual gate weight and travel; an undersized or marginal unit will not hold position reliably.
- Do not increase obstruction sensitivity or disable limits to mask coasting.
After adjustment, re-run the full test sequence: open and close limit stops, full-travel reversal on obstruction in both directions, photoeye trip and monitored-device fault response, and timer-to-close behavior. Record results on the commissioning checklist.
3. The homeowner insists on finishing today without the second photoeye. How should you handle handover and documentation?
Read the worked answer
Do not commission or hand over an automatic-closing gate without the required entrapment protection. Options:
- Compliant partial handover: configure the operator for constant-pressure (hold-to-run) operation only, which removes the automatic-closing hazard, and clearly explain that timer-to-close is disabled until the second photoeye is installed.
- Written deficiency notice: document the missing device, the standard/listing requirement it violates, and the date. Have the homeowner sign acknowledgment of the limitation and the quoted remediation.
- No verbal-only agreement. Record the conversation in the job file.
If the homeowner refuses both the compliant configuration and the remediation, stop work, leave the gate in a safe non-automatic state, and escalate per company policy. Handover documentation must reflect actual as-left condition, not the intended design.