• Relays, contactors, fans, motors and other inductive loads may produce voltage spikes when turning off the load that are strong enough to harm Themo and cause unreliability. An RC Snubber is required to be installed over the load to reduce these spikes. The RC snubber is installed between the phase and neutral of the load (L Load and N Load on Themo, A1 and A2 on the contactor).
A suitable RC Snubber can be found here: https://www.kotiautomaatiokauppa.fi/fi/tuote/shelly-rc-snubber
• So called ”silent” contactors are less likely to cause problems, as they usually have similar electronics embedded. However, there might be exceptions.
Hager ESC/ETC425S; ESC/ETC225S and ABB ESB16-20N contactors have been tested to work without an RC snubber.
See also: General Instructions for Themo Price Switch
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