Shelly 2L Gen4 Review: A No-Neutral Two-Channel Relay for Retrofitting Two Lighting Circuits
The Shelly 2L Gen4 is a compact two-channel in-wall relay for homes whose switch boxes have no neutral wire. It drives two separate lighting circuits from one module, powering itself from the live line with the included Shelly Bypass placed across the load at the first channel, and it speaks Wi-Fi, Bluetooth, Zigbee and Matter over Wi-Fi. Its limits follow from that focus: wet-contact outputs only, no energy monitoring, and a first channel rated for a lower switching power than the second. For retrofit lighting where a neutral is missing, it is one of the few relays that solves the problem cleanly.
- No-neutral retrofits
- Older homes and rental wiring
- Two lighting circuits on one relay
- Shelly and Home Assistant users
- Matter and Zigbee setups
Pros
- Controls two separate lighting circuits from one compact in-wall module
- No neutral wire needed, with the Shelly Bypass for 1L/2L included in the pack
- Wi-Fi 2.4 GHz, Bluetooth 4.2, Zigbee and Matter over Wi-Fi in one device
- Reaches Apple Home, Google Home, Alexa, SmartThings and Home Assistant, most through Matter
- Also repeats the Zigbee signal to extend the mesh
- Local control with scripting, MQTT, webhooks and over-the-air updates
- Overheating and overcurrent protection built in
- Small enough to hide behind an existing switch plate
Cons
- The Bypass is required at the first channel, which switches less power than the second
- No energy monitoring
- Wet-contact outputs only, with no dry-contact mode
- No cover, roller or interlock mode, so it is not for motors or shutters
- No 5 GHz Wi-Fi, Z-Wave or Thread
- In-wall only, with no DIN-rail mount
- No overvoltage or overpower protection
Who is the Shelly 2L Gen4 for?
It is for anyone who wants smart lighting control where the wall box has only a live wire and no neutral, the situation that rules out most smart relays. The 2L Gen4 powers itself from the live line, and a Shelly Bypass for 1L/2L ships in the pack to sit in parallel with the load at the first channel, which also lets the relay drive low-wattage LED lights with no minimum load. It suits people retrofitting two separate lighting circuits behind an existing switch plate, and because it offers Wi-Fi, Bluetooth, Zigbee and Matter, it works whether the rest of the home runs on Wi-Fi, a Zigbee network or a Matter platform. The module is small enough to hide behind a switch and can be paired with other units to cover more of the house.
What the Shelly 2L Gen4 offers
The headline is no-neutral installation with two channels: the device needs only the live wire, and the included Bypass handles the low-wattage LED case that would otherwise flicker or fail. It switches incandescent and LED lighting on both outputs, and the second channel also supports fluorescent lights and fans, with a higher switching power than the first. Connectivity covers Wi-Fi 802.11 b/g/n, Bluetooth 4.2, Zigbee 802.15.4 with repeater duty, and Matter over Wi-Fi, which is how it reaches Apple Home, Google Home, Amazon Alexa, Samsung SmartThings and Home Assistant. Two switch inputs (S1 and S2) plus a signal output (Sx) let existing wall switches keep working, and one control button handles pairing, factory reset and switching between Matter and Zigbee. The firmware adds schedules, scenes, local actions, scripting, MQTT, webhooks and over-the-air updates, all with local control, and overheating and overcurrent protection plus a three-year warranty round it out.
What to know before you buy
This is a lighting relay, not a general-purpose switch. The outputs are wet-contact only, so there is no dry-contact mode for potential-free jobs, and there is no energy monitoring, so it cannot report consumption; the Shelly PM models do that. It is not a cover relay either: with no interlock or roller mode it is not meant for blinds, shutters or gates, and a Shelly 2PM Gen4 is the two-channel model for those. The Bypass is required at the first channel, which is also the lower-rated output, so heavy loads belong on the second channel. There is no 5 GHz Wi-Fi, Z-Wave or Thread support, mounting is in-wall only with no DIN-rail option, and Zigbee works only with a compatible hub, whereas Matter runs over Wi-Fi rather than Thread.
Is the Shelly 2L Gen4 worth it?
If the problem you are solving is two light circuits with no neutral at the switch, the 2L Gen4 addresses it directly and without rewiring, and the bundled Bypass removes the usual low-load headaches. It gives you the full Gen4 protocol set, local control and broad platform support in a package small enough to hide behind the switch plate. Buy it for no-neutral lighting retrofits; if you need power metering, dry contacts, shutter control or higher loads, a different Shelly model is the one to choose.
Frequently asked questions
Does the Shelly 2L Gen4 need a neutral wire?
No. It runs from the live line alone, so it fits switch boxes without a neutral. A Shelly Bypass for 1L/2L is included in the pack and is wired in parallel with the load at the first channel, which also removes the minimum-load requirement for low-wattage LED lights.
Which smart home platforms does it work with?
Matter over Wi-Fi brings it into Apple Home, Google Home, Amazon Alexa, Samsung SmartThings and Home Assistant. It also supports Zigbee, but that path needs a compatible Zigbee hub.
How many lighting circuits can it control?
Two. The 2L Gen4 has two independent relay channels, each with its own switch input and output, so two lights can be switched separately from one module.
Does the Shelly 2L Gen4 measure energy use?
No. It has no power metering, so it cannot report consumption; the Shelly PM models cover that.
What kind of loads can each channel switch?
Both channels handle incandescent and LED lighting. The second channel also supports fluorescent lights and fans, and it switches more power than the first, which is the channel that needs the Bypass.
Can it control a roller shutter or blind?
No. The 2L Gen4 is a lighting relay with wet-contact outputs and no cover or interlock mode; a Shelly 2PM Gen4 is the two-channel model built for shutters and blinds.
