Knowledgebase
| Word | Description |
| NC/Normally Closed | Alarm system wiring in which detection device(s) use a switch or circuit that is closed when the door or window is closed, or active devices like motions are not being triggered (its “normal” condition). |
| NO/Normally Open | Alarm system wiring in which detection device(s) use a switch or circuit that is open when the door or window is closed, or active devices like motions are not being triggered (its “normal” condition). Fire devices normally use this style of circuit. |
