Security/Alarm Terminology and EOLR

In the alarm/security language can someone please define to me this; when a normally open (no continuity) door/window SPST contact is in its normal state (no magnet near to activate it) is it considered open? So if I were to say that I need an EOLR on a door contact that is normally open, would that mean that "normal" is when the door is open? Would I then install an EOLR in series or parallel? 
 
Just trying to clear up some confusion for myself. In my field of work as an electrician, NO NC mean just that, unchanged state without energizing or some other force. But the closed/open door contact state is got me second guessing my setup Thank you.

Normally open means that the switch has no continuity with no magnet near it. When attached to the panel a NO switch will measure ~12vdc at the panel when open and 0vdc when closed.
 
If an EOLR is used then it would be attached at the switch in series. With this arrangement the NO switch will measure 0vdc when open, ~7.4vdc when closed and ~12vdc would indicate a fault.
 
Have a look at page 9 of gthe installation manual.
 
 
 
EDIT!
 
I mixed up my numbers above
 
EOLR =
 
12vdc open
~7.4vdc switch closed
0vdc fault

The installation manual shows the resistor installed on the "+" or "zone" side of the switch. I installed my resistors on the "-" side of the switch. Can anyone explain to me if and how this makes any difference?
 
Mike.

dvpvic said:

In the alarm/security language can someone please define to me this; when a normally open (no continuity) door/window SPST contact is in its normal state (no magnet near to activate it) is it considered open? So if I were to say that I need an EOLR on a door contact that is normally open, would that mean that "normal" is when the door is open? Would I then install an EOLR in series or parallel? 

Click to expand...

 
In the alarm world, the "normal" position is the door/window closed (so that the magnet is actuating the reed switch). Therefore, what we call NC is really NO in your world.

SterlingDonnelly said:

 
In the alarm world, the "normal" position is the door/window closed (so that the magnet is actuating the reed switch). Therefore, what we call NC is really NO in your world.

Click to expand...

Thank you very much for the answer. So then resistors need to go in series on the negative side in a "NC" state? In this example let's us an M1 Gold panel

Page 9 of the install manual shows the resistor on the + side of the switch.

The way that I understand it is that normally means the state of the switch with no magnet. Normally open is an open (no continuity) switch when standing alone with no magnet.
 
Here's a link to an explanation of reed switches:
http://www.explainthatstuff.com/howreedswitcheswork.html
 
and a link to the install manual:
http://cache-m2.smarthome.com/manuals/128301.pdf
 
Mike.

SterlingDonnelly said:

In the alarm world, the "normal" position is the door/window closed (so that the magnet is actuating the reed switch). Therefore, what we call NC is really NO in your world.

Click to expand...

 
I would argue that NO or NC generally refers to the state of the circuit, not the switch.  You would use the type of switch necessary to maintain the NO or NC status of the circuit.  (Which as SterlingDonnelly points out, the switch may be the opposite of what you'd think).

JonW said:

 
I would argue that NO or NC generally refers to the state of the circuit, not the switch.  You would use the type of switch necessary to maintain the NO or NC status of the circuit.  (Which as SterlingDonnelly points out, the switch may be the opposite of what you'd think).

Click to expand...

I agree. So to maintain a NC circuit and supervise EOLR I would put the resistor series one Positve or negative.

That's where I had the confusion, is it the state of the circuit or contact. That makes a whole lot of sense

Folks like @DEL recommend putting the EOL resistor on the negative side of the contact. 

I never could understand how it makes any difference which side of the switch the resistor is on as long as it is located at the switch. The manual shows it on the + side and I do remember reading otherwise here in the past. I think that I remember something mentioned about multiple switches connected in a series???
 
Mike.

mikefamig said:

I never could understand how it makes any difference which side of the switch the resistor is on as long as it is located at the switch. The manual shows it on the + side and I do remember reading otherwise here in the past. I think that I remember something mentioned about multiple switches connected in a series???
 
Mike.

Click to expand...

 
 
@Sandpiper recently wrote up  a nice FAQ about EOLRs.  He has a lengthy description of the difference between installing the EOLR on the "+" side vs the negative side in Q32.  In most cases, it makes no difference, but installing on the negative side covers the case of a ground fault that installing on the positive side won't catch.

JonW said:

I would argue that NO or NC generally refers to the state of the circuit, not the switch.  You would use the type of switch necessary to maintain the NO or NC status of the circuit.  (Which as SterlingDonnelly points out, the switch may be the opposite of what you'd think).

Click to expand...

 
Yes, I would agree with your clarification. To take it a step farther, understanding if the switch is Form A, Form B or Form C would eliminate any doubt about what the "normal" position is as the definition for those Forms is constant.
 
Form A are open when not energized, Form B are closed when not energized and Form C support both configurations (three terminals on the contact instead of two).

Bottom line - a form A switch is set to zone type "1 = normally closed" in Elk RP.
 
This will cause an armed system to be silent when the door is closed (magnet near switch) and alarm when the door opens.
 
Mike.

SterlingDonnelly said:

Yes, I would agree with your clarification. To take it a step farther, understanding if the switch is Form A, Form B or Form C would eliminate any doubt about what the "normal" position is as the definition for those Forms is constant.
 
Form A are open when not energized, Form B are closed when not energized and Form C support both configurations (three terminals on the contact instead of two).

Click to expand...

 

mikefamig said:

Bottom line - a form A switch is set to zone type "1 = normally closed" in Elk RP.
 
This will cause an armed system to be silent when the door is closed (magnet near switch) and alarm when the door opens.
 
Mike.

Click to expand...

What's there to be confused about?!?  :rofl: