Leviton Decora Smart Motion Sensing Dimmer Switch, Wi-Fi 2nd Gen, Neutral Wire Required, Works with My Leviton, Alexa, Google Assistant, Apple Home/Siri & Wired or Wire-Free 3-Way, D2MSD-1RW, White

What I installed and where

I put the Leviton motion dimmer in two spots that really expose a switch’s strengths and weaknesses: a windowless laundry room and a kid-heavy bathroom. Both benefit from hands-free lighting, and both see a mix of short visits and lingering tasks. I also tried it in a hallway 3-way using one wired companion in one home, and later with a wire-free companion in another. Across those spaces, I used it with dimmable LEDs and a magnetic low-voltage (MLV) transformer to check its rated loads.

Installation and wiring

If you’ve swapped a Decora-style switch before, the physical install is familiar. The unit is moderately deep, but it fit in my standard single-gang plastic box alongside typical wire nuts. Key notes:

• Neutral required: This is non-negotiable. If your box lacks a neutral bundle, this isn’t the right product.
• Line/load identification: The included wire leads make it straightforward, but 3-way travelers can trip people up. Label your conductors before disconnecting the old switch.
• 3-way options: You can do a traditional wired companion (DD00R/DD0SR) for one additional location, or add “Anywhere” battery remotes to create multi-way control without pulling new cable.

Once wired, the app walks you through Wi‑Fi setup. On one network the switch joined on the first try; on another I had to rerun pairing a couple times before it took. After the first firmware update, it’s been stable.

If you have metal wall boxes or decorative metal plates, expect some Wi‑Fi signal loss. It’s 2.4 GHz only, so a nearby access point helps. In one install with a metal plate and the AP two rooms away, I saw occasional slow responses until I switched to a plastic plate and reserved the switch’s IP.

Motion sensing that behaves

Motion-first switches live or die by how well they know when to turn on and—just as important—when to stay off. The sensor in this dimmer has three pieces that made it work well in daily use:

• Occupancy/vacancy modes: Auto-on/auto-off (occupancy) for the laundry room; manual-on/auto-off (vacancy) for the bathroom during late evenings.
• Adjustable timeout and sensitivity: I set the bathroom to a short timeout for nighttime trips and dialed sensitivity down a notch to avoid false-ons from hallway traffic.
• Ambient light threshold: This is critical. I set the laundry room to ignore motion when the door is open and adjacent light is already bright. Result: no pointless daytime activations.

I didn’t have to babysit behavior once those dials were set. The sensor’s field of view caught normal movement and still saw slower, smaller motion like folding laundry. For edge cases (soaking in a bath with minimal movement), setting a slightly longer timeout avoids blackouts.

Dimming performance and trim

Leviton’s dimming curve is one of the better ones I’ve used in a Wi‑Fi switch. Out of the box it delivered smooth fades with no “steppy” transitions. Two features stand out:

• Min/max trim: You can cap the top end and lift the bottom to tame finicky bulbs and eliminate shimmer. This saved a set of bargain LEDs that otherwise flickered at low levels.
• Preset level and fade rates: I prefer a 60% default for the laundry room and a very gentle 2-second ramp up/down in the bathroom. Both can be set in the app.

I ran one circuit with a 450 VA MLV transformer and did not encounter buzz from the switch or transformer. That said, dimmer hum is often a bulb or transformer issue; if you hear it, adjust trim first and verify your load is truly compatible.

If you need an old-school on/off for a fluorescent fixture, there’s a non-dimming mode that disables the dimmer output. It worked as advertised in a garage test.

App, automations, and voice

The My Leviton app is utilitarian in a good way: fast pairing (after the occasional retry), clear settings, and no subscription or hub required. Useful options I relied on:

• Night settings: Automatically cap the brightness at a low level during defined hours. Midnight bathroom trips no longer blast my retinas.
• Schedules and scenes: Daily schedules for early morning preheat and bedtime shutoff, plus triggerable scenes. You can link motion to control other Leviton devices via Room Response—handy for turning on a stair light when the hallway sensor trips.
• Multi-user access: Household members could use the app without friction.

For broader ecosystems, the switch exposed itself cleanly to Apple Home, Alexa, and Google Assistant. Siri and Alexa both handled dim/bright commands instantly after linking. In Apple Home, I folded the switch into scenes and automations; in Alexa, voice control was snappy and reliable.

3-way and wire-free companions

In a traditional 3-way, the wired companion mirrored on/off and dimming, which is not universal among smart dimmers and a plus here. For a second project, I used a wire-free Anywhere Companion mounted on a wall where no wiring existed. It paired easily and mimicked the main switch’s behavior closely, including dimming. If you’re chasing multi-location control without opening walls, this is a clean solution.

Two caveats:

• For wired 3-way, plan on one companion. If you need more locations, use the wire-free remotes.
• Keep companions within reasonable range of your Wi‑Fi/switch; they don’t rely on your network for every press, but initial pairing and sync benefit from a healthy signal.

Ergonomics and build

This is a Decora-style paddle with a slim side rocker for dimming. Tapping the paddle toggles power; the side rocker adjusts level. I prefer press-and-hold dimming on the main paddle, but after a week the muscle memory for the side control set in. The locator LED is subtle and can be dimmed or disabled, which I appreciate in bedrooms.

The face is clean and modern, though completely smooth. In pitch darkness, finding the side rocker for fine adjustments is a bit fiddly, so I mostly rely on a single paddle tap at night—balanced by night-mode low brightness.

The industrial design feels robust, and the buttons have a crisp action without relay clatter. Thermals stayed cool under typical LED loads.

Reliability and connectivity

After initial setup, mine stayed online and responded instantly to local app and voice commands. Two tips if you’re chasing rock-solid stability:

• Give the switch a reliable 2.4 GHz signal. If your AP is distant or you’re in a metal box with a metal plate, consider a closer AP or a plastic wall plate to reduce attenuation.
• Reserve its IP and let it complete firmware updates on day one. Post-update behavior improved noticeably on one install.

If your environment is RF-hostile and you need bulletproof connectivity, a dedicated RF system with a bridge (e.g., proprietary mesh) can be more forgiving than Wi‑Fi. But in a typical home network, this switch behaved well.

Where it shines—and where it doesn’t

Use it if you want:
- Hands-free lighting that respects ambient daylight
- Fine-grained dimming, trim, and night behavior
- Native Apple Home, Alexa, and Google control without a hub
- Flexible 3-way via either a single wired companion or wire-free remotes
- The option to have motion trigger other Leviton gear

Think twice if:
- Your boxes lack a neutral
- You need multiple wired companions in a 4-way/5-way and don’t want remotes
- Your load is outside spec (e.g., ELV drivers not supported here)
- Your network coverage is weak and you can’t address it

The bottom line

The Leviton motion dimmer hits the right balance of sensor intelligence, dimmer quality, and platform support. The motion logic is practical rather than gimmicky, the dimming is smooth with useful trim controls, and the “Night Settings” feature proved more valuable than I expected. I’d like the option to dim by holding the main paddle, and initial Wi‑Fi pairing can require a couple attempts, but these are small nits in an otherwise well-rounded package.

Recommendation: I recommend this switch for anyone who wants reliable, hands-free, platform-agnostic lighting control with thoughtful dimming features. It’s especially good in utility spaces, kids’ bathrooms, and hallways where occupancy logic and night modes pay daily dividends. Just confirm you have a neutral, mind your Wi‑Fi signal if you use metal boxes or plates, and you’ll get a smart, quiet workhorse that plays nicely with the rest of your home.