Although there are different styles to select from, there are basically two types of sirens, inside and outside. The inside siren is designed to be placed within the home and is intended to alert the occupants of an alarm. The outside siren is designed to be placed on the outside of the building to draw attention to premises.

On a system that is only burglarly, one siren placed on the main floor is the norm. If your system includes smoke detectors, there are code requirements for where and how many sirens must be used. There are decibel requirements for instance that must be met at the pillow on each bed in all bedrooms. That measurement must be taken with any doors between the siren and the bed in the closed position. There must be at least one siren on each floor of the structure. Also, the siren must produce a different sound for a fire than it does a burglarly. A burglarly is usually indicated by a steady siren that may change tones as it sounds. A fire is indicated by what is called a temporal 3 alert. This consists of a 1/2 second siren, 1/2 seconds of silence, 1/2 seconds of siren, 1/2 seconds of silence, 1/2 seconds of siren, followed by 1-1/2 seconds of silence and then repeated. This is applicable to both inside and outside sirens

Outside sirens are designed to withstand the elements and are usually louder than inside sirens. They may be an open horn type of design or they may be enclosed in a housing with trip switches that will set off the alarm if a would be burglar attempts to dismantle the housing. We normally recommend outside sirens on every system that we sell. It not only draws attention to the home or business in alarm, it gives the burglar incentive to get the heck out of dodge. It's not uncommon for an outside siren to be audible up to a mile away, no burgular is going to hang around long with that noise going on.

The style of siren that is used depends upon your application but the purpose and effect is the same.
SEM Security Systems
a division of Southeast Mobility Inc