Smart 3-way switch: the neutral wire comes first

3-way and 4-way switches: the words

The Office québécois de la langue française calls it a single-pole double-throw switch, or two-way switch: a switch with three terminals, one input and two outputs, used in pairs to turn a light on and off from two separate control points.

In Canada, manufacturers say “3-way”: a three-way setup controls fixtures from two locations. The English “three-way” actually counts the switch’s total number of terminals.

To control the same light from three locations, you move to a four-way setup: one four-way switch plus two three-way switches.

What a smart switch adds

A smart switch contains a communication radio and a clock, on top of controlling the light. Depending on the model, it connects to your Wi-Fi network or to a hub.

At Sinopé, based in Saint-Jean-sur-Richelieu, the lighting controls are all Zigbee: one wall switch and two dimmers, no Wi-Fi switch. These devices must be connected to a compatible hub. Other manufacturers sell Wi-Fi models that only need a network with internet access, no hub.

At STM-Électrique, we replace your standard switches with smart dimmers and switches, and we favour the certified Sinopé ecosystem. To make the whole house smart, thermostats included: Smart home (in French).

The neutral wire: why most smart switches need one

A regular switch simply cuts the power. A smart switch must stay powered even when the light is off, for its radio and clock: that is the neutral wire’s job, one manufacturer explains.

At Sinopé, the wall switch and both lighting dimmers require a neutral wire.

Don’t go by appearances: a white wire in the box is not necessarily a neutral. When power goes to the light fixture first, the white wire can serve as the run to and from the switch. The same manufacturer adds that not all buildings are wired the same way, and that installation should be done by an electrician.

No neutral in the box: the options

Sinopé gives two options when the box has no neutral wire: add one, or install the switch somewhere else.

Some manufacturers also sell no-neutral models. At one of them, those models then require a ground connection and a Wi-Fi bridge. The same manufacturer warns that a smart dimmer wired without a neutral can make the bulb flicker and keep it from working properly.

Which option fits your home depends on what is in your boxes: an electrician checks before suggesting a model.

The two control points

On a 3-way circuit, two points control the same light, and the model you choose decides what goes at each one.

• Sinopé’s wall switch can be used alone or in a 3-way setup.
• Its adaptive-phase dimmer works in 3-way with switches only: the other control point stays a switch, not a second dimmer.
• Sinopé also allows a “virtual” 3-way: two smart devices linked by automations in its Neviweb app.

The right setup depends on where the power comes in and where the wire to the light leaves, Sinopé specifies. That is what the electrician looks at when opening the boxes.

A dimmer on LED lights: Choosing a dimmer for LED lights.

Wi-Fi, hub, bulbs: what to check before you buy

• The network. A Wi-Fi model needs a network with internet access; a Zigbee model, a compatible hub.
• The neutral. Check what the model requires, and what your box contains.
• The load. Each model has a maximum load: 450 W of LED for Sinopé’s wall switch, 150 W of dimmable LED for its dimmers.
• Certification. In Québec, it is prohibited to install unapproved electrical equipment; a product certified to Canadian standards usually shows a “c” at the 8 o’clock position on its mark.

Getting it installed by a master electrician

Replacing a switch, adding a neutral or moving a control point is electrical work. In your home, only a master electrician can carry it out, and Sinopé itself requires its devices to be installed by a certified electrician, in line with the codes in force.

Our master electricians are Sinopé certified. The quote is written and free.

For the lighting itself, fixtures and dimmers: Indoor and outdoor lighting installation (in French).

Frequently asked questions