STI Backplate for Stopper II® and Weather Stopper® - STI-1280

STI STI-1280 Lock Backplate for Stopper II and Weather Stopper Series

Overview

The STI-1280 is a replacement backplate engineered for STI Stopper II and Weather Stopper series electromechanical locks. It provides the mounting interface and electrical connection required for proper lock operation in access control installations. Operating at 9VDC, it integrates directly with standard access control power supplies and backup battery systems. Deploy this when replacing a worn or damaged backplate, or when upgrading an existing lock assembly in both interior and weather-exposed exterior applications.

Key Features

• 9VDC Operation: Runs on standard access control power supplies and battery backup systems — no special voltage conditioning needed, and low current draw means it won't strain a shared power budget across multiple locks on a single panel.
• Stopper II and Weather Stopper II Compatibility: Designed exclusively for these two lock series. Stopper II is a larger electromechanical lock body; Weather Stopper II adds a protective polycarbonate cover and weather gasket for outdoor durability. Both use the STI-1280 as the mounting and electrical interface.
• Weatherproof Gasket Support: When paired with Weather Stopper II, the backplate design accommodates a protective gasket seal, extending operational life in rain, salt spray, and temperature swings — critical for exterior-mounted strikes on loading docks, chemical storage, or maritime facilities.
• Four-Point Mounting: Secured with four fixing holes drilled with a 7mm masonry bit. Fully tightened mounting prevents vibration-induced loosening in high-traffic areas where door slamming and repeated cycling can fatigue fasteners.
• Wall Fixings Included: Hardware provided for secure installation to concrete, masonry, or metal door frames — no need to source separate anchors for standard mounting scenarios.
• Surface Installation Flexibility: Spacer inserts available to blank off unused cable entry holes, allowing clean installations whether wired for single-conductor or multi-conductor control runs.

Integration and Compatibility

The STI-1280 backplate integrates with any access control power supply delivering 9VDC — common on panel-mounted supplies rated for multiple locks. Verify your existing lock body is either Stopper II or Weather Stopper II before ordering; this backplate will not fit unrelated STI lock models or competing brands. When replacing a worn backplate on an active door, power down the circuit first to avoid nuisance strikes during installation.

For Weather Stopper installations, position the weather gasket over the device before securing the frame to ensure environmental sealing. This is particularly important in coastal or high-humidity environments where salt corrosion or condensation inside the strike can cause electrical faults.

What's in the Box

• 1x STI-1280 Backplate assembly
• Wall fixings (quantity and type for standard masonry/concrete mounting)

Frequently Asked Questions

Q: Is the STI-1280 compatible with the original Stopper series lock?

A: No. The STI-1280 is designed exclusively for Stopper II and Weather Stopper II series locks. Original Stopper locks use a different backplate design. Confirm your lock body series before ordering.

Q: Can I use the STI-1280 outdoors without the Weather Stopper II cover?

A: The STI-1280 backplate itself is not rated for direct weather exposure. If mounting outdoors, use it only with Weather Stopper II, which includes the protective polycarbonate cover and gasket. For interior-only doors, the backplate alone is sufficient.

Q: What voltage does the STI-1280 require, and will it work with my existing power supply?

A: The STI-1280 operates at 9VDC. Verify your access control power supply outputs 9VDC before installation. Most standard access control panels include a 9VDC auxiliary supply for lock circuits; consult your panel documentation to confirm.

Q: How do I prevent the backplate from loosening after installation?

A: Ensure all four fixing holes are fully tightened during installation. In high-traffic areas with heavy door slamming, check fasteners periodically and re-tighten if needed. Over-tightening may strip holes in softer substrates — use a steady hand and stop when resistance is firm.

Q: What is the warranty on the STI-1280?

A: The STI-1280 carries a manufacturer warranty. Contact the manufacturer or your distributor for specific warranty terms and coverage.

Eden Phillips

The STI-1280 is a straightforward replacement backplate for Stopper II and Weather Stopper II locks — the kind of component you're reaching for when a strike has been hammered by thousands of door cycles or salt spray has corroded the mounting interface. At 9VDC, it's a lightweight electrical load and integrates into any standard access control panel with a dedicated lock supply. The distinction between Stopper II and Weather Stopper II matters: Weather Stopper II adds a polycarbonate shield and gasket seal, so if you're mounting this on an exterior door, confirm you have the full Weather Stopper II assembly before ordering the STI-1280.

Technical Highlights:

• 9VDC Nominal Voltage: Runs on standard access control auxiliary supplies with no special conditioning. Low power draw means multiple locks can share a single 9VDC rail without voltage sag — typical for retrofit installations where you're adding a second or third door to an existing panel.
• Four-Point Masonry Mounting: 7mm drilling requirement is standard for concrete and brick; the four-point design resists vibration loosening far better than two-point fastening, which is why this layout became the Stopper II standard.
• Weather Gasket Accommodation: The backplate design leaves room for Weather Stopper II's polycarbonate cover and rubber gasket — skip this if you're installing interior-only, but if you're upgrading from an interior Stopper II to an exterior Weather Stopper II, the STI-1280 is your direct drop-in replacement.

Deployment Considerations:

• Verify your lock body is Stopper II or Weather Stopper II before ordering. Unrelated STI lock models use different backplate designs — a wrong order wastes a truck roll.
• Power down the 9VDC circuit during backplate replacement to avoid nuisance strikes when you disconnect the old unit. Even though 9VDC is safe to touch, a live strike during installation is a lockdown risk.
• For outdoor Weather Stopper II installations, position the gasket over the device before tightening the frame — this is a fussy step, but skipping it leaves a moisture path straight into the strike mechanism.

The STI-1280 is the right choice for retrofit replacements and Stopper II lock maintenance in commercial buildings, industrial facilities, and secured perimeter doors. It's not a feature-rich component — it's a wear item — but correct compatibility and solid four-point mounting make it the proven baseline for Stopper II service life.