A method of handling power failures in a mains powered first gateway (12'; 34) of a home wireless alarm system, the system comprising the mains powered first gateway , at least one second gateway and a plurality of wireless peripheral nodes, said mains powered first gateway (12'; 34) and the at least one second gateway communicating with and controlling at least one of the plurality of wireless peripheral nodes and communicating with a remote central monitoring station, said mains powered first gateway (12'; 34) comprising a plurality of electronic units including a control unit , the method comprising the steps: a) continuously storing energy supplied from a mains source in an energy storing device of the mains powered first gateway (12'; 34), b) continuously monitoring changes in a power supply voltage level Vin from a DC power source, c) filtering the power supply voltage level in a first low pass filter, d) detecting a drop of filtered power supply voltage level below a predetermined threshold value, wherein said detecting is made in a power fail detector comprising a second low pass filter connected to a power supply at power supply voltage level Vin to provide said threshold value, and wherein the second low pass filter has a second time constant T2 that is substantially higher than a first time constant T1 of the first low pass filter , e) generating a power fail signal after detecting said drop of power supply voltage level while obtaining energy from said energy storing device , f) transmitting said power fail signal to the control unit of the mains powered first gateway (12'; 34), said control unit communicating a power loss information signal to the central monitoring station, and g) reducing power consumption by turning off selected electronic units in the mains powered first gateway (12'; 34), so as to prolong operating time of said mains powered first gateway (12';34) during a time period sufficient to allow a communications unit of the mains powered device to send the power loss information signal to the central monitoring station. a) continuously storing energy supplied from a mains source in an energy storing device of the mains powered first gateway (12'; 34), b) continuously monitoring changes in a power supply voltage level Vin from a DC power source, c) filtering the power supply voltage level in a first low pass filter, d) detecting a drop of filtered power supply voltage level below a predetermined threshold value, wherein said detecting is made in a power fail detector comprising a second low pass filter connected to a power supply at power supply voltage level Vin to provide said threshold value, and wherein the second low pass filter has a second time constant T2 that is substantially higher than a first time constant T1 of the first low pass filter , e) generating a power fail signal after detecting said drop of power supply voltage level while obtaining energy from said energy storing device , f) transmitting said power fail signal to the control unit of the mains powered first gateway (12'; 34), said control unit communicating a power loss information signal to the central monitoring station, and g) reducing power consumption by turning off selected electronic units in the mains powered first gateway (12'; 34), so as to prolong operating time of said mains powered first gateway (12';34) during a time period sufficient to allow a communications unit of the mains powered device to send the power loss information signal to the central monitoring station. <EOS>