Zooz ZEN51 Dry Contact Relay

Quick verdict

The ZEN51 hides behind your existing switch and makes it smart. Your wall plate stays the same, your spouse stays happy, and Home Assistant gets Z-Wave control. Wiring is simple if you are comfortable with electrical work, but this is not a beginner device.

Standout: Tiny behind-the-wall relay that makes any existing switch Z-Wave smart without replacing the switch itself.

Last checked: 2026-03-22

Compatibility snapshot

Why it stands out

• tiny form factor fits behind most switches or inside junction boxes
• makes any dumb switch smart without replacing the switch itself
• Z-Wave 800 series with Long Range support for improved range and reliability

Reasons to hesitate

• wiring behind an existing switch requires electrical confidence and is not plug-and-play
• single relay only, so if you need two, look at the ZEN52
• tight fit in shallow or crowded gang boxes

Best for

• making existing dumb switches smart without changing the switch plate
• adding Z-Wave control to devices like garage doors or low-voltage systems

Avoid if

• you are not comfortable wiring behind a switch or in a junction box
• you want dimming, since this is on/off relay only

Privacy and local-control notes

Pure Z-Wave device. No cloud, no data collection. Now available with Z-Wave Long Range in some regions.

Home Assistant support: supported · integration path: Z-Wave JS.

Buying reality check

Price notes: Affordable for a Z-Wave 800 relay. Cheaper than replacing the whole switch if you like your existing hardware.

Compare side by side: see relay comparisons →