Is a door contact NC or NO?

Un-believable, All door contacts are N/C they go O/C when the door is opened, which causes the alarm to activate.
Regards
Nick

Nick
October 2010

C`mon only open ccts now really are pressure mats and how often do we use them?
Even flood warning devices now are NC.

Alarm
October 2010

to be serious,it can be both,depends on how the alarm is configured,the contacts can be set as open to fire the panel,or closed to fire panel,depends on the system config

gts
October 2010

Try the other way around.

Alarm
September 2010

not this time mate

gts
September 2010

But then on reflection - Normally open when not activated - and closed when activated

Peccavi's friend
September 2010

I know nothing of security systems but...

If the sensing device (switch or whatever) was set to have Normally open contacts when the door or window was closed and secure - then if anybody cut the wires and the door/window subsequently opened - the system would not know about it.

My guess therefore is - Normally Closed - opening the door/window or cutting the wires will have the same effect.

But I am often wrong on here...

Peccavi
September 2010