Kantech TR1675 KT-400 Step-Down Transformer
The Kantech TR1675 is a hardwired step-down transformer engineered to convert standard 110 VAC line voltage into safe, regulated 16.5 VAC output—the backbone voltage for most low-voltage security devices. Rated at 75 VA, it supplies consistent power to door locks, card readers, intercoms, and control modules without overload risk. This is the kind of component that disappears into a panel installation but creates real operational headaches if undersized or misconfigured.
Key Features
- 110 VAC to 16.5 VAC conversion: Step-down ratio is fixed, so you don't need to configure or verify secondary voltage—it's always the same. Eliminates field guesswork on transformer selection.
- 75 VA power capacity: Supports multiple low-voltage devices on a single circuit without nuisance resets or brownout conditions. Sufficient for a typical single-door access control loop (lock, reader, exit device).
- Wire-in hardwired installation: Direct connection to 110 VAC line power via breaker or disconnect—no plug-and-play convenience, but no external enclosure or power supply to fail either. Simplifies retrofit panel designs by eliminating separate power supply footprint.
- UL certification: Meets National Electrical Code safety and construction standards, required for code-compliant commercial and institutional deployments. Skip the TR1675 in regulated environments and you risk final inspection rejection.
- Reduces control panel complexity: Eliminates the need to source and integrate separate power supplies into your panel layout. One transformer handles voltage stepping for multiple low-voltage loops.
- Compatible with Kantech and third-party security platforms: Works with Kantech access control systems and integrates into any architecture requiring 16.5 VAC auxiliary power—door controllers, keypads, intercom interfaces.
Deployment Context
Deploy the TR1675 in retrofit and new-build access control installations where 110 VAC line power is available at or near the main control panel. Common use cases include single-door or multi-door access control loops, supplemental power for intercom handsets, and auxiliary circuits for electronic strike locks. In distributed multi-building installations, you may need more than one transformer to keep voltage drop within acceptable limits—plan for approximately 4–5 devices per 75 VA supply before considering a second unit.
The wire-in design assumes a qualified electrician handles the 110 VAC connection; this is not a field-swap component. Once installed behind a breaker or disconnect, it requires no maintenance. Verify your local electrical code and building authority requirements before specifying—some jurisdictions mandate specific transformer types for security systems.
Technical Specifications Summary
- Input: 110 VAC
- Output: 16.5 VAC at 75 VA
- Installation: Wire-in hardwired
- Certification: UL
- Model: KT-400
Frequently Asked Questions
Q: Can I use the TR1675 to power multiple doors at once?
A: Yes. The 75 VA capacity supports multiple devices on a single circuit—typically one lock, one card reader, and one exit device per transformer. If you're powering more than four or five devices or longer cable runs (50+ feet), consider a second transformer to maintain voltage stability.
Q: Is the TR1675 suitable for outdoor installations?
A: The transformer itself is UL-rated but not specifically engineered for outdoor exposure. Mount it indoors or in a weatherproof enclosure. The devices it powers (readers, locks) may be outdoors; the transformer must remain dry.
Q: Do I need a breaker or disconnect for the TR1675?
A: Yes. Wire it through a standard 110 VAC circuit breaker or disconnect switch. This is code requirement and provides emergency cutoff. Your electrician will handle this as part of installation.
Q: Is the Kantech TR1675 NDAA-compliant?
A: The TR1675 is a passive electrical component (no embedded electronics or firmware). NDAA applicability is not relevant to transformer procurement, but verify your overall system integrator's compliance posture.
Q: What's the voltage drop over distance with the TR1675?
A: Voltage drop depends on wire gauge, distance, and total load. For runs longer than 50 feet at full 75 VA load, use 14 AWG or heavier wire. Consult NEC guidelines or ask your electrician to model the circuit before installation.
Q: Can I parallel multiple TR1675 units for higher capacity?
A: No. Transformers in parallel risk circulating currents and phase mismatch. If you need more than 75 VA, specify a single larger transformer or separate independent circuits on different units.
Ted PerryPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
I specify the TR1675 in hardwired access control retrofits where 110 VAC is already present at the panel location. The 75 VA capacity is a practical middle ground—enough to handle a standard single-door loop (lock + reader + exit device) without the overhead of oversized industrial transformers. The fixed 16.5 VAC secondary eliminates field configuration errors, and the UL certification keeps your design compliant with local electrical code on the first inspection.
Technical Highlights:
- 75 VA output: Sufficient for 4–5 typical low-voltage security devices. Beyond that load, voltage sag becomes visible—you'll see delayed lock release or card reader latency. Plan accordingly in multi-door designs.
- Wire-in hardwired installation: No external enclosure, no plug connectors—one less failure point in the field. The tradeoff is that installation requires a licensed electrician and coordination with the main electrical disconnect.
- Fixed 16.5 VAC secondary: No adjustment or calibration needed. You don't need to verify voltage with a meter on commissioning—it's always correct.
Deployment Considerations:
- Verify circuit breaker availability in your main panel before specifying. Some retrofit locations have no spare breaker slots, forcing a sub-panel install—additional cost and schedule impact.
- Watch voltage drop on long runs. If your card readers or locks are mounted 75+ feet from the TR1675, the secondary voltage may sag below 14 VAC under full load, causing intermittent reader failures. Model the circuit with your electrician first.
- This transformer is a passive component—no remote monitoring or firmware updates. If a device on the 16.5 VAC circuit draws excessive inrush current (motor-driven strike, solenoid), it won't shut itself down. You rely on the breaker to protect it.
The TR1675 is the right choice for single-building, single-to-multi-door retrofits where electrical code compliance is non-negotiable and load is moderate. Skip it if you need monitored or intelligent power distribution—those deployments call for supervised power supplies with relay reporting and fault detection. For a straightforward hardwired installation in a commercial office or warehouse, this is the standard workhorse.
