There are 1000 milliamps in 1 Amp. Every technology attached to a security system draws current, and this is measured in milliamps, for example: a control panel generally has a 1 Amp power supply built into it, from that we need to deduct the power need for every PIR, Shock sensor, Bell box etc. If we took a basic system in normal mode it would be drawing approx. 550 milli-amps, but in alarm condition this I could jump up to about 900 milli-amps.