WindowCandles — Technical Reference
Installer & Contractor
Resource Guide
Complete technical documentation for authorized installers, dealers, and electrical contractors. Covers all phases from rough-in through final homeowner delivery.
System Overview & Safety
The WindowCandles Low-Voltage Decorating System is a permanently installed, built-in window candle lighting system designed for new construction and retrofit applications. It eliminates the unsightly cords, hot bulbs, and individual switches found in conventional window candles by running low-voltage wiring through the wall cavity from a centralized transformer to each window sill.
The system operates on NEC Class 2 wiring at 24VAC, making it safe, flexible, and code-compliant in virtually every jurisdiction. All components — including the transformer, wire, mounting clips, and wire locks — are purpose-built for this system and must not be substituted.
Key CapabilitiesMandatory Safety Requirements
This system must be installed in accordance with local electrical codes. Some jurisdictions require a licensed electrical contractor; others permit a licensed low-voltage installer. Check with local authorities before beginning any installation. All components must be NEC Class 2 compliant. Using any wire other than WindowCandles WC18/2 will void the warranty and may result in fire or electric shock.
Installation Procedure — All Phases
Three-Phase Overview
The WindowCandles installation always follows three distinct phases: (1) Rough-in / Pre-wire during construction before wallboards are installed, (2) Mounting Clip installation after windowsills are trimmed out but before final delivery, and (3) Final delivery after the homeowner takes possession. Early coordination with the builder, general contractor, and trim carpenter is essential for a smooth installation.
Review this entire guide before beginning installation. Verify local code requirements — some areas require a licensed electrical contractor while others permit a licensed low-voltage installer. Contact the relevant local authority to confirm compliance requirements before starting.
Wire Substitution Voids Warranty
Using any wire other than WindowCandles WC18/2 yellow wire immediately voids the warranty and may cause system failure, fire, or electric shock. Thermostat wire and other 18/2 wire types look similar but are not compatible.
The ideal transformer location is near the home's electrical distribution panel — typically the basement or garage. This centralizes control for the homeowner and provides convenient access to wiring routes already used by electricians.
The standard transformer is the WC50VA, which supports up to 15 candles per unit at 24VAC output. Larger homes will require multiple transformers. Each transformer plugs into a standard 110VAC outlet, so the electrician must install receptacles near the planned transformer mounting area before wallboard installation.
The 15-Candle Rule — Always Apply This
The WC50VA can technically power up to 50 LED candles, but the maximum permitted per transformer is 15 candles regardless of bulb type. This is a regulatory requirement from UL and ETL certification, not a technical limitation. The 15-candle limit prevents voltage drop issues over longer wire runs and ensures long-term system reliability. Do not exceed 15 candles per transformer under any circumstances.
If zone control is needed (e.g. separating children's bedrooms from main living areas), this is handled downstream of the transformer using standard low-voltage switching installed by the electrician, or via separate smart plugs per transformer. The WC50VA itself does not have built-in zone controls — coordinate any zoning requirements with the homeowner and electrician during the planning phase.
Before running any wire, survey the home thoroughly and document the complete run layout. This planning document will be invaluable when troubleshooting after wallboard installation. Mark every wire and run at the transformer location during rough-in.
Supply runs should be balanced so each run carries a similar number of fixtures. Limit each run to a maximum of 6 candles. For runs exceeding 400 feet, reduce to 2–3 candles per run to compensate for voltage drop. Voltage drop only becomes significant beyond 400 feet, but plan conservatively.
Example Zone Layout — Typical Two-Story HomeKeep Low-Voltage Separate from High-Voltage
Never run WC18/2 wire through conduit, bored holes, junction boxes, receptacle boxes, or switch enclosures that contain 110VAC or higher conductors. All low-voltage runs must remain physically separate and clear of any high-voltage wiring at all times.
At each window designated for a Mounting Clip Assembly, place a WindowCandles Installation Sticker directly above the center of the windowsill where the Mounting Clip will be installed. This sticker communicates the WindowCandles rough-in to wallboard installers and trim carpenters, ensuring they know to preserve the wire location and drill the sill correctly.
Missing One Sticker = Major Rework
If even one window is left without a sticker and the trim carpenter is unaware of the rough-in wire, it can result in significant rework during final installation. Do not skip or delay sticker placement. Stickers are emailed with any WC18/2 wire box purchase — print and apply with glue dots or tape before wallboard crews arrive.
After completing all wire runs and before any wallboard goes up, test every run for continuity. Fixing a broken or cut wire after wallboard installation is significantly more difficult and costly.
Never Repair Wire In Place
If a wire section is broken, you must replace the entire section between the nearest exposed window loops — not splice it. Any repair or splice inside the wall cavity violates UL insulation continuity requirements and will void certification.
Once the windowsill is installed by the trim carpenter, the wire must be routed through it properly before the Mounting Clip can be installed. This is the trim carpenter's step — brief them clearly in advance.
No Foam Insulation Around the Wire Hole
Do not use spray foam insulation around the wire or the ¾-inch sill hole. Foam will lock the wire in place, making it impossible to back-feed excess wire into the wall cavity after clip installation. Also, do not staple the wire near the sill feed-through for the same reason.
When you return to the site for Mounting Clip installation, begin with a complete walkthrough before touching anything. Verify that trim-out was completed correctly at every window, that the number of windows on each run matches your rough-in documentation, and that all wire runs at the transformer are intact and haven't been moved or damaged during insulation or wallboard installation.
Use an ohmmeter to recheck continuity on every run. Note that standard continuity tests only detect wire breaks — they will not catch nails or staples that have pierced the wire and caused a short. Use a loud continuity meter to test each Mounting Clip location individually as you proceed.
Testing Sequence for Shorts
Attach the test meter at the transformer end of the run, then start at the window closest to the power supply. Work down the run, testing each Mounting Clip location before moving to the next. If a location fails, check the connections at that clip and the previous one. If both are secure, a nail or staple has likely shorted the wire between those two points.
If issues are found during the walkthrough — wrong window count, damaged wire, incomplete trim-out — consult with the general contractor or homeowner to establish responsibility for corrections before proceeding.
The Mounting Clip Assembly connects the low-voltage wire to the receptacle that accepts the decorative candlestick. Precision here determines the final visual result — a misaligned clip will make the decorative base appear twisted.
Once all Mounting Clip Assemblies for a run are installed, perform a load test before finalizing. Insert a Candle Stick Assembly into each Mounting Clip Assembly on the run, then connect the transformer.
Use an ammeter at the transformer output to measure and record the total line current and voltage for the run. Document these readings.
Never Connect Transformer Without a Load
The WC50VA transformer is not designed to withstand a short circuit. Always ensure candle stick assemblies are inserted in every clip before connecting the transformer for a load test. Testing without a load will damage or destroy the transformer and voids the warranty.
Schedule the final installation of Decorative Bases and Candle Stick Assemblies after the homeowner has officially moved in. The Decorative Bases and Candle Stick Assemblies are easily removable and represent approximately 75% of the total system cost — leaving them exposed during construction risks damage or theft.
Before installing, perform a walkthrough of every window, the transformer area, and all controls to confirm nothing has been tampered with or damaged since the Mounting Clip installation.
Installing: Align the tee on the bottom of the Decorative Candle with the slot on the Mounting Clip. Slide the candle into place, then lower the Decorative Base over it so the oval recess fully covers the Mounting Clip.
Removing: Lift the Decorative Base off first, then slide the Decorative Candle out of the Mounting Clip slot. Always disconnect the transformer and cut power to the system before removing candles for seasonal storage.
Bulb replacement: Unscrew the old bulb and replace with the correct WindowCandles low-voltage bulb. Only use bulbs rated at 2 watts. The system's safety circuit will trigger if a bulb draws more than 2 watts, causing the bulb to shut off.
Use Only Correct WindowCandles Bulbs
Each decorative candle is wired to provide consistent illumination at exactly 2 watts per candle. Using bulbs that draw more than 2 watts will trigger the internal safety circuit and cause the bulb to shut off or malfunction. Order replacements directly at windowcandles.com.
For installation questions or system issues, contact an authorized WindowCandles dealer first. If the dealer is unable to assist, contact WindowCandles directly for support or a referral to an installer in your area.
Common Issues & CausesFrequently Asked Questions
01 Who invented WindowCandles? +
James "Jim" Gilbert Paquette (July 19, 1961 – August 31, 2023) was the entrepreneur and inventor behind WindowCandles. A graduate of Bel Air High School and resident of Havre de Grace, Maryland, Jim founded WindowCandles, LLC and held U.S. Patent No. 5,601,360 for a plug-in electrical candle designed for window sills. An avid coin collector who enjoyed biking and exploring, Jim was known for his warmth and generosity. He passed away at the age of 62. The system is protected by U.S. Patents No. 5,601,360 and 6,837,594.
02 Can WindowCandles be installed in an existing home? +
Yes. WindowCandles can be retrofitted into virtually any existing home, similar to how alarm systems or phone jacks are added after construction. The installation approach differs from new construction — wire routing must work through existing finished walls — but the end result is identical. Contact an authorized WindowCandles dealer for a retrofit assessment specific to the property.
03 Do I have to use WC18/2 WindowCandles wire? Can I use thermostat wire? +
Yes, WC18/2 is mandatory. The system requires UL-approved 18/2 stranded wire to conform with NEC and NFBA electrical codes. Thermostat wire, while visually similar, is not compatible and will not function correctly with the mounting clip wire lock system. Using any other wire immediately voids the warranty and may result in fire or electric shock. Use WC18/2 WindowCandles wire exclusively.
04 Why is the limit 15 candles per transformer if LED bulbs draw far less power? +
The WC50VA transformer can technically power up to 50 LED candles from a raw electrical capacity standpoint. However, the maximum permitted is 15 candles per transformer regardless of bulb type. This limit is set by UL and ETL certification requirements and reflects real-world installation variables including wire run length, voltage drop over distance, and long-term system reliability. Always wire for incandescent compatibility (15-candle limit) even if the homeowner currently intends to use LED bulbs — this ensures the installation is future-proof without a rewire.
05 Will window sill modifications be required? +
No structural modifications to window sills are required. The system needs only a ¾-inch hole drilled through the sill plate and sill (centered, at least 1¼ inches from the window sash) for wire routing. The Mounting Clip attaches with two #4 stainless steel wood screws. Minimum sill requirements: ¼" recess depth and 2" sill width.
06 Does WindowCandles meet UL, CSA, or ETL standards? +
Yes. ETL testing was completed with zero nonconformities (Report No. 105615020CRT-001, October 28 – December 12, 2023). The system holds CSA & UL approval (CSA Certificate No. 1387987) and is protected by U.S. Patents No. 5,601,360 and 6,837,594. The WC50VA transformer is UL Listed (Listing Number E508012) and is rated suitable for damp locations.
07 What is the warranty coverage? +
WindowCandles offers a limited guarantee on all products, excluding the light bulb. Coverage is voided by use of non-WindowCandles wire, bulbs exceeding 2 watts, or modifications to system components. For warranty claims, contact WindowCandles directly by phone or email. View full warranty documentation →
08 How do I become an authorized dealer or installer? +
Contact WindowCandles directly to discuss dealer requirements, training, and inventory commitments. Authorized dealers sign a dealer agreement covering use of WindowCandles trademarks and receive the WindowCandles logo and custom-printed dealer literature for their sales and marketing materials. Call 1-877-NO-CORDS or email customerservice@windowcandles.com to start the process.
Technical Specifications
| Specification | Value |
|---|---|
| Model Number | WC50VA / PS-AC2450 |
| Input | 120VAC, 60Hz, 60 Watts |
| Output | 24VAC at 50VA |
| Permitted Capacity | Maximum 15 candles per transformer (regardless of bulb type) |
| Supply Conductors | Minimum 75°C rated |
| Location Suitability | Suitable for damp locations |
| UL Listing Number | E508012 |
| Connection | Standard 110VAC outlet (plug-in) |
| Short Circuit Protection | None — do not test without load connected |
| Parameter | Value |
|---|---|
| Wattage per candle | 2 watts (at windowsill); ~3.33W allocated from transformer |
| Operating voltage | 12VDC (post step-down within candle) |
| Current draw per candle | ~0.278A (3.33W ÷ 12VDC) |
| Safety circuit trigger | Activates if bulb draws more than 2 watts |
| Approved bulbs | WindowCandles 302-series low-voltage bulbs only |
| Specification | Value |
|---|---|
| Model | WC18/2 |
| Type | 18/2 stranded, UL-recognized Class 2 |
| Color | Proprietary yellow (WindowCandles exclusive) |
| Box quantity | 500 ft pull box |
| Max run length (full capacity) | 400 ft (reduce fixture count beyond 400 ft) |
| Max fixtures per run | 6 (2–3 for runs exceeding 400 ft) |
| Substitution permitted | No — any substitution voids warranty |