Dear customer,

 Netro will allow one sensor to monitor up to 3 zones but the user needs to make sure the zones have similar environmental conditions. This feature will be ready in a future version of the app in one month. 

Thanks,

Netro Support

Hi...the purely on/off conditions of the series approach should be more reliable, and less prone to false triggers.  Parallel wiring will not have a "full swing" response for a single switch. You could use that effect though, to determine how many of the switches are open, for example.

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