Every now and then, I’ve been asked how to install three or more sirens for an alarm panel. Since most security systems typically have a max output of 1000 mA, 3 or more sirens would overload the panel.
A solution would be to use an external relay to power up the additional sirens.
A simpler solution is to use Interlogix Security’s MPI-47 series of sirens. They draw 175 mA and come in three different mounting styles: recessed rectangular, recessed round or surface round. I prefer the recessed round in most cases because it is least conspicuous among the three. With a piezo sound output of 106dB, it can be very intense, especially if multiple ones are installed!