Finnleo CB17-3 Contactor Box (3-phase, Laava & Magma)

Finnleo CB17-3 Contactor Box (3-Phase) — Laava & Magma Sauna Heaters

What the CB17-3 Contactor Box Does

The Finnleo CB17-3 Contactor Box is the dedicated three-phase power relay engineered for Finnleo's Pro Series sauna heaters — Laava and Magma. These commercial-duty heaters draw far more current than a SaunaLogic2 control's low-voltage electronics can switch directly, so the CB17-3 steps in as the heavy-duty intermediary: it receives the low-voltage command signal from the SaunaLogic2 control (SL2 or SL2-C) and uses its internal contactors to switch full three-phase line power to the heater's elements safely and reliably. Installed outside the sauna enclosure in a dry, accessible electrical space, it carries a minimum ambient rating of 90°C, shielding its switching hardware from heat while staying close enough to the heater circuit for a clean, code-compliant installation.

Heater and Electrical System Compatibility

The CB17-3 is required specifically for three-phase electrical service on Finnleo's Pro Series lineup — the Laava heater and the Magma heater in its three-phase 208V and 480V configurations. Unlike the residential Designer SL2 and Himalaya heaters, which pair with the CB16 series, Laava and Magma's higher kW output (Magma spans 21.0, 24.0, and 28.8 kW models across a 720–2,000 cubic foot room range) demands the CB17's heavier-duty three-phase contactor rating. Wiring details vary by voltage: 480V three-phase Magma installations typically run on a single CB17-3, while 208V three-phase Magma setups require a CB17-3 paired with a CB18-3 add-on to handle the additional load split. On dual-heater configurations — common in larger commercial saunas using two Magma floor heaters — two CB17-3 boxes (each with its own CB18-3 where applicable) may be needed to serve the heaters independently. Because contactor sizing is tied directly to heater kW, voltage, and phase, always confirm your exact heater model and electrical service before ordering — pairing the wrong contactor box can prevent proper operation or fail electrical inspection.

Construction & Installation

The CB17-3 is built as a rugged, self-contained electrical enclosure housing UL/NRTL-listed contactors rated for continuous commercial sauna duty at three-phase loads. It connects on one side to the low-voltage control wiring coming from the SaunaLogic2 control head, and on the other to the incoming three-phase line-voltage feed and the outgoing circuit to the heater elements. Like all Finnleo contactor boxes, it must be installed by a qualified electrician outside the sauna room, in accordance with local electrical code and the clearance/temperature requirements specified in the heater's installation manual. Its enclosure is designed for wall or panel mounting near the heater's electrical disconnect, keeping wiring runs short and serviceable, and it accepts the CB18-3 add-on directly where a split-load configuration is required.

Why the CB17-3 Matters

Without the correct contactor box, a SaunaLogic2 control cannot safely operate a Pro Series heater on three-phase service — the control's low-voltage touchscreen and app electronics simply aren't built to switch line-voltage loads at commercial kW levels. The CB17-3 is the component that makes the entire SaunaLogic2 experience — touchscreen operation, Wi-Fi app control, scheduling, and voice assistant integration — actually function on three-phase Laava and Magma installations. It's a small, unglamorous box, but it's the electrical backbone that lets a large commercial or high-demand sauna respond instantly and safely to every command sent from the control head or the app.

Why Choose Finnleo

Finnleo, built by Sauna360 in Cokato, Minnesota, is one of the most trusted names in authentic Finnish sauna, and every component in its SaunaLogic2 ecosystem — from the touchscreen control down to the contactor box — is engineered, tested, and listed to work together as a matched system. As an authorized Finnleo dealer, we offer full factory warranty coverage, expert help matching your CB17-3 to the correct heater and electrical service, and support before and after your purchase. Not sure whether your Laava or Magma installation needs a CB17-3 alone or paired with a CB18-3, or whether your service is single- or three-phase? Send us your heater model and electrical specs and a sauna specialist will confirm the exact pairing before you order.