Normally closed / normally open

[bernardgreen]

It was a Warden Call system that had to be connected to a city wide paging system when resident wardens ( at least one per community ) were replaced by travelling wardens. The system was classed then as an emergency call system.

 

[Europlex]

As Sparky says that type of system, not an intruder alarm, was/is wired open circuit, why, I don't know but always has been for as long as I can remember.

 

[PBC_1966]

Plenty of smoke (and heat) detectors have normally open alarm contacts. Integrity of the loop can be monitored with end-of-line resistors.

 

[sparkymarka]

Again that's A FIRE alarm NOT a INTRUDER alarm........

 

[Europlex]

Not really interested in what happens in the US with your Fire Alarms (& don't get me started on your Intruder Alarm Systems) we are talking about an English, Warden Call system.

 

[SandyLyon]

Although I never use them, most "Pressure Mats" when used in intruder alarm systems are N/O devices.

 

[Budnzeus]

God we had a pressure mat in the 90's my brother used to always miss in with he was drunk and wake everyone up. Ended up getting a contact one front door instead

 

[Europlex]

Although I never use them, most "Pressure Mats" when used in intruder alarm systems are N/O devices.

Are they still in use then for alarms, have not seen any used for many, many years?

I thought they were only used for people in nursing homes and the like getting out of bed.

 

[Budnzeus]

This was back in the 90's