Mr Spock
Active Member
The question is regarding how to put the 5 windows in this one room shown below onto a single input zone of an HAI panel. The windows are casement type with magnetic sensor switches. I wanted to home run each window's 22/2 wire pair to the panel for optimum flexibility and troubleshooting capabilities. However when I schematically think of how to wire this up, including EOL resistors, I don't see how to do it without some potentially big downsides.
Assumptions:
1) When a magnetic switch is "secure" (window closed) it is low impedance or effectively a short.
2) The panels must be presented with approximately 1k ohms if secure (from EOL resistor), a short if in a "trouble" condition, and an open if in alarm.
Options
1) I could put each window on a separate zone, but that eats up input zones real fast.
2) I could put all 5 windows on one zone by wiring up the 5 windows in series at the server room with one EOL resistor at the panel. However if there is a short in any one of the wires then it will always look like that window and therefore the whole zone is OK (no trouble indication).
3) I could put the wires in series at the windows (no individual home runs) with one shunt EOL resistor for the group. However making all the connections at the windows will reduce my flexibility and make it much harder to identify where a bad connection is located.
4) I could put all 5 windows on one zone by wiring up the 5 windows in series at the server room with an EOL series resistor at each window. However the trouble condition that will not register with the HAI panel because there are 5 resistors and each must be 1/5 of the total required (nominally 1k ohm, or 200 ohms each). The voltage drop change provided by removing a 200 ohm resistor from the loop would be too low to register as a trouble condition.
So unless I've missed something this is how it works and what my options are. I would probably go with option 2.
Please weigh in with your comments and suggestions.
Thanks.
EDIT: assumptions.
Assumptions:
1) When a magnetic switch is "secure" (window closed) it is low impedance or effectively a short.
2) The panels must be presented with approximately 1k ohms if secure (from EOL resistor), a short if in a "trouble" condition, and an open if in alarm.
Options
1) I could put each window on a separate zone, but that eats up input zones real fast.
2) I could put all 5 windows on one zone by wiring up the 5 windows in series at the server room with one EOL resistor at the panel. However if there is a short in any one of the wires then it will always look like that window and therefore the whole zone is OK (no trouble indication).
3) I could put the wires in series at the windows (no individual home runs) with one shunt EOL resistor for the group. However making all the connections at the windows will reduce my flexibility and make it much harder to identify where a bad connection is located.
4) I could put all 5 windows on one zone by wiring up the 5 windows in series at the server room with an EOL series resistor at each window. However the trouble condition that will not register with the HAI panel because there are 5 resistors and each must be 1/5 of the total required (nominally 1k ohm, or 200 ohms each). The voltage drop change provided by removing a 200 ohm resistor from the loop would be too low to register as a trouble condition.
So unless I've missed something this is how it works and what my options are. I would probably go with option 2.
Please weigh in with your comments and suggestions.
Thanks.
EDIT: assumptions.