Although some of Maretron's SIM100 accessories have built in power supervision relays like the smoke/heat detector (Maretron part number SH-449CSTE) and carbon monoxide detector (Maretron part number CO-CO12224T), the gas detector does not have a built in power supervision relay. However, power monitoring can be added to the gas detector using an external power supervision relay. Please see the following wiring diagram for adding a power supervision relay to the gas detector.