Wiring Requirements

Last updated: August 11, 2026

Mysa for Baseboards requires line voltage wiring routed to the thermostat location first, so a complete circuit exists at the gang box (not just at the heater).

Wire count

You need 4 or more wires in your gang box — typically two bundles connected by wire nuts:

  • 240V systems: 2 line wires (L1/L2 in) + 2 load wires (L1/L2 out)

  • 120V systems: 2 wires bringing power (Line and Neutral) + 2 wires going to the heater

Minimum gauge: 12/2 AWG

Only see 2 wires?

Remove the old thermostat and check inside the gang box — extra capped wires are often tucked inside.

If you truly only have 2 wires, the thermostat location only breaks the circuit and cannot power a smart thermostat. See When You Only Have 2 Wires for your options, or email install@getmysa.com.

Important: check all wires present in your electrical box, not just the ones connected to your current thermostat — many existing thermostats only use 2 wires even when additional wires are available.

A note on 240V circuits

240V circuits have no neutral wire. Both the black and white wires are "hot" (indicated by a double-pole breaker in your panel) — the white wire is not a neutral in this configuration.

Standard wiring configuration

  1. L2 (Red terminal): connect to all white wires in the box

  2. L1 (Black terminal): connect to one group of black wires (usually bundled together)

  3. Load (Black terminal): connect to the remaining black wire(s) going to the heater

  4. Ground wire: not required — if present, coil it up and tuck it into the back of the box

Single pole vs. double pole

Mysa for Baseboards is a single pole thermostat. It can replace:

  • Single pole thermostats — direct replacement

  • Double pole thermostats — works, but check local building codes (some regions require double pole for baseboard heaters)

A double pole thermostat disconnects both legs of a 240V circuit when off; a single pole thermostat disconnects only one leg. Both are safe, but regulations vary by region.

Get Support

Take a photo of your wiring and email install@getmysa.com.