Wiring Smart Glass & Smart Film on Swing Doors Using a Power Loop

Quick Overview of Wiring Smart Glass Doors With Power Loops

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Wiring smart glass and smart film on a moving (swing) door requires a flexible, protected electrical path from the fixed frame into the moving glass. A power transfer loop (also called a power loop or mini power loop) routes low-voltage power through a flexible conduit or hinge so busbars at the glass edge can be fed by a transformer and controller. Use concealed loops whenever possible, follow busbar polarity and connector specs, protect wires from repeated flexing, and verify transformer sizing with your PDLC / switchable glass datasheet.

Keywords used: smart glass, smart film, smart glass doors, switchable glass doors, power transfer loop, power loop, mini power loop, smart glass wiring, wiring smart film.

Why a Power Transfer Loop is Ideal for Smart Glass Swing Doors

• Motion protection: Wires that move with the door are subject to fatigue and pinching. A power loop contains the cable in a flexible, armored conduit (gooseneck) preventing damage.
  
  
• Aesthetics: Concealed loops or mortised loops keep wiring hidden for a clean look — critical in hospitality and high-end interiors.
  
  
• Security & reliability: A protected pathway reduces tampering and keeps power delivery stable for privacy switching.
  
  
• Compatibility: Power loops are a proven solution used for electrified hardware (locks, exit devices) and are ideal for switchable glass doors too.
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Interested in other wiring scenarios for switchable glass doors? Visit our smart glass wiring guide.

Typical System Components (items you will see / need)

• Smart glass or smart film (PDLC) panel with busbars along the edge.
  
  
• Busbar connectors (solder tabs, crimp terminals, or manufacturer-supplied connector assembly).
  
  
• Power transfer loop (flexible conduit; surface-mounted or concealed mortise style) or power transfer hinge / magnetic connector for some designs.
  
  
• Low-voltage transformer / power supply and PDLC-compatible controller.
  
  
• Low-voltage wiring (gauge per installer manual — commonly 18–22 AWG for short runs, but confirm).
  
  
• Fasteners, grommets, strain reliefs, and firestopping where cables pass walls/ceilings.
  
  
• Multimeter and test equipment for commissioning.
  
  

NOTE: Check your specific PDLC / smart glass datasheet for exact voltage/current and connector requirements. Manufacturer specs always take precedence.

Step-by-Step Installation: Swing Door Wiring with a Concealed Power Loop

1. Plan & specify before cutting or mortising

• Review the smart glass / smart film product data (voltage, polarity, maximum run length).
  
  
• Decide loop type: concealed mortise loop (preferred for aesthetics) or surface-mounted loop (faster install). Mini power loops are used when space is tight (narrow frames/stiles).
  
  
• Locate transformer/controller in an accessible but discreet place (ceiling void, adjacent wall cabinet).
  
  
• Confirm cable lengths + slack for full door travel.
  
  

2. Prepare the door & frame

• Verify stile depth and decide routing through stile → door loop → frame.
  
  
• Pre-drill access holes for concealed loops if using mortise type. Use grommets and strain relief at pass-throughs.
  
  
• If using a power transfer hinge or magnetic connector, confirm compatibility with door thickness and glass edge clearance.
  
  

3. Install the power transfer loop (conduit)

• Mount one end of the conduit securely to the fixed frame and the other to the door edge (or hinge area), following the hardware instructions.
  
  
• Ensure the conduit’s gooseneck can flex throughout the door’s full swing without pinching or over-stretching.
  
  
• For mortised loops, test fit and finish before final sealing.
  
  

4. Pull and secure the wiring

• Pull the low-voltage cable from the transformer location through the wall/ceiling into the frame junction box.
  
  
• Feed the cable through the power transfer loop conduit into the door stile and to the glass edge.
  
  
• Use cable clamps inside the door and frame to prevent movement at connection points. Always use strain-relief.
  
  

5. Connect to the busbar / glass edge

• Expose the glass busbar connection point per the product instructions (some smart film systems have busbars pre-laminated; others require connector assembly).
  
  
• Use the manufacturer-recommended method to attach the wires to the busbar: soldering, crimp terminal, or dedicated connector block. Maintain correct polarity.
  
  
• If magnetic connectors or specialized plug assemblies are provided, install per the vendor instructions for a serviceable connection.
  
  

6. Tie into controller + transformer

• Connect door-side cable end at the fixed-frame junction box to the PDLC controller input, respecting polarity and connector type.
  
  
• Connect controller to transformer/power supply according to the controller manual.
  
  
• Install any switches (momentary, toggle), relays, or integration with building automation (if required).
  
  

7. Test & commission

• Before final sealing, test continuity and resistance with a multimeter.
  
  
• Power the system and cycle the glass between clear and private states. Verify switching reliability while moving the door through full range of motion.
  
  
• Inspect the conduit flex, cable slack, and strain relief; make adjustments as needed.
  
  
• Record all wiring changes, label wires, and capture photos for the installation record.

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Best Practices & Pro Tips

• Use concealed loops when possible — they give the cleanest finished look.
  
  
• Keep transformer/controller accessible (ceiling void or service panel) for maintenance.
  
  
• Label both ends of every cable — makes future troubleshooting fast.
  
  
• Avoid sharp bends where the cable exits the conduit — use grommets and small-radius supports.
  
  
• Protect cable from snagging by securing inside the door with clamps.
  
  
• Confirm wire gauge for the run length and current; longer runs may need heavier gauge to avoid voltage drop.
  
  
• Use flexible, armored conduit rated for door motion and with an expected life-cycle equal to the door use.
  
  
• Use serviceable connector solutions (e.g., magnetic connectors, quick disconnects) where access is needed for glass replacement.
  
  
• Coordinate with door hardware vendor — electric locks and other electrified devices may share the loop and need segregation or separate conductors.
  
  

Safety, Regulations & Codes

• Always follow local electrical codes. Even though PDLC is typically low-voltage, local code may require qualified electrician involvement.
  
  
• Maintain required fire ratings where cables pass fire walls; use listed firestop systems if necessary.
  
  
• If the door is on an egress path, ensure all electrified hardware complies with building and life-safety codes.
  
  
• For exterior doors, use weather-rated components and ensure conduit is rated for environmental exposure.
  
  

Troubleshooting & Common Issues

Symptom: Glass does not switch.

• Check transformer and controller power LED.
  
  
• Verify busbar connections and polarity.
  
  
• Confirm cable continuity through power loop (multimeter).
  
  

Symptom: Intermittent switching when door is moving.

• Inspect cable strain relief and check for pinching inside conduit.
  
  
• Ensure connector contacts are secure and not oxidized.
  
  

Symptom: Visible arcing or heat at connector.

• Power off immediately. Likely poor connection or undersized wire for current. Inspect and replace connector; consult manufacturer.
  
  

Symptom: Noise or hum during switching.

• Could be controller grounding or interference. Verify grounding, controller mounting, and nearby EM sources.

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Accessibility & Automation Integration

• Consider mounting controllers so they can connect to building automation systems (BACnet, KNX, RS-485, dry contact).
  
  
• For ADA or touchless operations, integrate switching with occupancy sensors or voice/automation triggers.

Installation Checklist

• Confirm PDLC / smart glass voltage & current specs
  
  
• Choose loop type (surface / concealed / mini / hinge)
  
  
• Measure cable lengths with door travel tolerance
  
  
• Order connector kit, conduit, grommets, strain reliefs
  
  
• Place transformer/controller in accessible location
  
  
• Test continuity before powering system
  
  
• Install and label all connections & photo-document
  
  
• Final commissioning and stress test through full door operation
  
  

FAQs

Q: What is a power transfer loop?
A: A power transfer loop (power loop / mini power loop) is a flexible protective conduit that carries electrical wires from a fixed frame to a moving door, protecting cables during motion and providing a neat, secure route for power and data.

Q: Can smart film be installed on operable doors?
A: Yes. Both factory-laminated switchable glass and retrofit smart film (PDLC) can be used on moving doors when wired correctly with a power transfer loop, busbar connections, and controller. Proper routing and strain relief are essential.

Q: Do I need a special transformer?
A: Use the transformer / power supply recommended by the smart glass / smart film manufacturer and size it with appropriate headroom. Check PDLC controller specs for exact voltage and current requirements.

Q: What’s the difference between a mini power loop and a full power loop?
A: A mini power loop is a narrower, low-profile flexible conduit for tight stiles or slim frames. A full power loop is generally larger and can carry more conductors or thicker cables for high-current devices.

If you’re planning a project with smart glass doors or wiring smart film and want expert help specifying a power transfer loop, transformer sizing, or installation best practices, contact Smart Glass Country’s technical team. We can provide wiring diagrams, spec sheets, and project consultation.

Have a question? Contact us and we will be happy to answer.