HUUM UKU Extension Box 63 (UKU Ext Box) for High-Power Sauna Heaters – 240V 2x63A

HUUM UKU Ext Box (H2003012) is the dedicated UKU Extension Box 63 designed to expand the electrical switching capability of HUUM’s UKU control system for higher-output electric sauna heaters. Built to work alongside UKU Wi-Fi and UKU Local controller setups, this add-on module is used when your heater installation requires an extension box so the control system can manage a larger electrical load safely and correctly.

If you’re building a larger sauna or upgrading to a more powerful HUUM heater, the controller’s main module may not be enough on its own for your heater size. In those cases, the UKU Ext Box becomes the essential interface that supports the proper wiring scheme for bigger heaters—helping keep the installation aligned with HUUM’s specified connection method for high-power models.

This extension box is intended for use with HUUM electric sauna heaters that fall into the higher kW range covered by HUUM’s extension-box wiring scheme (including common large-heater sizes and model families). It is commonly paired with HUUM HIVE and other higher-power HUUM heaters during residential and commercial projects where larger heater outputs are required.

What the UKU Ext Box does in a UKU system

The UKU control system is a combination of a control panel and a main module that handles heater control and safety inputs. For larger heaters, HUUM specifies an extension box wiring scheme that integrates the UKU control unit with the heater using the UKU Extension Box 63. In practical terms, the Ext Box is part of the correct electrical architecture for certain high-output installs—so your UKU control can be used with larger heaters while following HUUM’s prescribed wiring approach.

Electrical rating and installation intent

The UKU Extension Box 63 is rated for 240V operation and is designed around a dual 63A connection scheme at 60 Hz. It is a hardwired electrical component and should be installed by a qualified electrician, following all applicable national and local electrical and building codes, plus HUUM’s wiring instructions for the extension box. HUUM specifies placement outside the steam room, located near the UKU main module, and mounted to the wall.

Compatibility notes (important)

• The UKU Extension Box 63 is specified for use with UKU Wi-Fi and UKU Local controller models.

• It is used for the heater-connection scheme HUUM provides for larger heaters (the wiring scheme covers select higher-power HUUM models and sizes referenced in the extension box instructions).

• If you’re unsure whether your heater output requires the Ext Box, match the heater’s kW rating and model to HUUM’s control/extension-box requirements for your region and installation type.

When you’re planning a high-power sauna heater installation, getting the control architecture right matters as much as choosing the heater. HUUM’s UKU Ext Box is the purpose-built component for projects that need the extension-box wiring approach—so you can keep the UKU control experience while meeting the needs of larger heater loads.