How to Install a Kasa HS220 3-Way Dimmer Kit

Overview

Install the Kasa HS220 3-way dimmer and companion switch in a standard 3-way circuit with neutral wiring, pair with the Kasa app, and validate dimming behavior from both switch locations for smart control.

Why This Happens in Real Homes

The Kasa HS220 3-way dimmer kit is a master dimmer plus an add-on switch that together control one light from two locations — and like all Kasa switches, it requires a neutral wire in the box. The master goes in the box with line (incoming power), and the add-on connects back to it via the traveler wire.

Turn off the breaker, identify which box has the line versus the load, and install the master dimmer where the power comes in with neutral connected. Wire the add-on in the second box and run the traveler between them per the kit's diagram, connecting grounds. Restore power and onboard the master on 2.4GHz WiFi. Getting neutral and the traveler right is what makes both locations dim the light.

What's Included

• Installing the HS220 3-way dimmer kit
• Master + add-on wiring questions
• Add-on not working
• Which box gets the master
• Traveler wire questions
• No neutral in the box
• Lights won't dim from both
• Companion not detected

Got your materials ready? Here's what to check first.

Before You Start

• Neutral wire required and missing
• Master vs add-on in the wrong box
• Traveler wire not connected between them
• Line/load not identified correctly
• Ground not connected
• 3-way wiring differs from existing
• Add-on not wired to the master properly
• Breaker off / air-gap pulled

Tools & Requirements

Installation Steps

1

Kill Power and Map

Turn off the breaker and confirm power is off using a non-contact voltage tester. Open both switch boxes and photograph existing wiring before disconnecting. Write down which conductor is line, load, ground, and travelers. A clear map prevents costly mistakes during install.

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2

Install HS220 Primary

Choose the box with line conductor and neutral bundle as the primary. Land line on L, load on Load, travelers on Traveler, neutral on N, and ground on green. Tighten terminals firmly. The primary is the only location that needs neutral for smart features.

3

Install Companion

At the secondary box, install the Kasa companion switch. Connect travelers and ground per the instruction diagram. The companion does not require neutral and does not appear as a separate smart device because it communicates with the primary via travelers.

4

Power Up and Pair

Restore breaker power. Open Kasa, tap Add Device, and choose Smart Dimmer. Complete onboarding and select your 2.4GHz WiFi. Confirm the primary switch responds to app dim commands before moving the phone near the secondary switch for manual testing.

5

Test From Both

Toggle the primary HS220 and the companion to verify dimming from both ends. Test presets and schedules. If behavior looks reversed, swap traveler wires per the wiring guide. Confirm LEDs do not flicker at low dim levels, then label both boxes.

Installation Tips

Still stuck? This is usually the deeper cause below.

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