| Conventional Systems | | | | route(s) to that of the detector wiring. |
| The philosophy of a conventional system revolves | | | | It is therefore important when designing a |
| around dividing the building into a number of areas | | | | conventional system to ensure that the panel has |
| called zones - the detectors and callpoints within | | | | adequate zone capacity for the size and |
| each zone are then wired on dedicated circuits. | | | | complexity of the building and that the panel can |
| | | | support the intended sounder circuit wiring and |
| It is then necessary to manually search the | | | | loading. |
| indicated zone to pinpoint the exact cause of the | | | | 2 Wire Systems |
| fire alarm. | | | | 2 wire systems are based on standard |
| In addition to the detection circuits, there is | | | | conventional system technology, but incorporate |
| also a need for separate circuits for alarm | | | | additional functionality to enable both the |
| annunciation devices such as sounders and | | | | detectors and the sounders for each zone to be |
| beacons, to signal the existence of a fire alarm | | | | wired on a single common circuit. |
| condition to the building users. | | | | 2 wire technology thereby enables the control |
| For sounder circuit continuity monitoring to | | | | panel to use a single circuit per zone for detection |
| function effectively, sounder circuits must be | | | | and to power the sounders |
| wired in a single radial circuit - spurs and tees are | | | | Even though the panel continually powers the |
| not permitted. | | | | sounders, additional control functionality within |
| Almost every conventional fire panel will have | | | | each sounder enables them to be activated only |
| facilities for more than one sounder circuit. In | | | | in the event of a fire alarm condition. |
| general, the number of sounder circuits increases | | | | By combining the detection and alarm |
| with the number of detection zones provided and | | | | annunciation wiring into a single circuit, considerable |
| or the specification of the panel. | | | | savings in installation time and cabling can be |
| Normally, however, there will be fewer | | | | achieved. |
| sounder circuits than detection zone circuits, so it | | | | Although adding 2 wire technology to the |
| will be necessary for a sounder circuit to provide | | | | detectors and sounders slightly increases |
| cover for more than one zone. | | | | equipment costs, this is normally more than |
| This increases installation complexity by | | | | offset by savings in installation - resulting in a |
| forcing the sounder wiring to follow a different | | | | reduced total cost for the system. |